# Audi 80 2L 8V No spark issue Digifant



## Blazius (Nov 2, 2018)

Hello, for the past 2 weeks or so I've been chasing a dreaded no spark issue with my recently acquired Audi 80 b4 2L 8V ABK with Digifant 1. The car was running fine and etc when i bough it and brought it home and stuff. But 2 days later when I started it up, it started up just fine but then it died in about a min or so, I've tried restarting it but to no avail, so I took off the battery negative or something I did but next day it started up again fine until it died the same way every since then I couldnt start it up no matter what, this was like 2 weeks ago, ever since I've been trying to figure what is up with this thing.

So I tried service manual with the checks on full ignition system etc. but before that I've replaced : Distributor ( the whole thing) , Ignition coil with module ( the newer style 6N0 xxx p/n) , Spark plug wires, and spark plugs. 
The distributor is fine and so is the supply and wires to ecu connector which is a Digifant 1 with 38 pin connector not the newer 45 pin one. 

On coil connector I get flashes between pin 2 and pin 3 ( + ) as it should be, but I cannot get it to flash between pin 1 ( ground) and pin 2 ( signal) but according to manual it should but ever since then I figured out that the signal /trigger wire is not a 12V but rather a frequency modulated lower voltage like 2V, 2.5V or so running at 30hz when engine is idle ( 800~ rpm) so my 12v Led tester wont flash there, so I connected multimeter to check voltage but it stays on 0 all the time. Also all the wires have proper continuit and supply specially the signal wire. to ECU

It also doesnt flash if i check between terminal 1 and terminal 15 on the coil and it also should. Also I've been trying to manual fire the coil with 12 supply and it works kind of. But still Im trying to figure out what kind of trigger signal is coming in to trigger it with constant 12v to pin3 and constant ground on pin 1 since I cannot manually discharge it like that.

The only thing that should be left is the ECU, but I also opened the ECU and there is no physical damage that I can see unlike other digifants that like to burn up tracks and stuff. So how couldve it gone bad.

I'd much appreciate some help with this issue its driving me crazy.


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## Butcher (Jan 31, 2001)

I do not have a wiring diagram in front of me. They're all loaded on my old laptop and I have not swapped the data over yet.

All coils work pretty much the same. There is a power terminal and a trigger terminal. Once the ground is removed from the trigger terminal, there should be a spark. It's that simple.

In the old days, they had points that would open and close when the engine is running. Once the points opened, the ground would go away and that is when the spark occurred. The distributor had as many lobes for the points as the cylinders. So if you had a 4 cylinder, you have 4 lobes. Every time the lobe goes around, the points opened and the spark would occur. 

Points went away since they are not that great and would wear out. The wear occurred at the rubbing block or the actual points themselves. Once there is wear, the points would open at the wrong time and therefore the ignition timing would be effected. 

So instead of points, they use electronics. It does not matter how the electronics work as long as they do work. All of the electronics just provide and remove a ground signal. The coil makes the spark. If there is no ground trigger, there is no spark. So all the fancy electronics provide the ground trigger. That is really all you need to know since you cannot really change what goes on inside those fancy black boxes.

The electronics for the ignition starts from the distributor. Then the signal goes to the fuel injection ECU. Once it goes there, the fuel injection ECU provides a signal to remove the ground to the coil. Since the ECU is not strong enough to handle that load, they use an amplifier. This part was available separately but now they come with the new ignition coil. These coils are usually square-ish verses the standard round cylinder type coils. 

You need to test the signal at the distributor so see if there is one. What will it be? I really do not know but I believe it is a hall effect sensor. That means you use you DC volt meter. A hall effect sensor needs power and ground to work [that's 2 of the wires] and then there is a signal wire. Since you only have 3 wires, you should be able to determine which is power and which is ground. I suspect the supply voltage would be anywhere from 5-12V. All you need to do is turn on the ignition and find which one provides that. You can start with grounding one of the leads to the volt meter and probing the wires to see which has voltage. Then hook the volt meter wire to power and use the other lead to find the ground wire on the distributor. Once you find the supply wires, the last wire is the signal wire.

Crank over the engine and watch the signal wire. Since it is a hall effect signal, you should get a power/ground signal. The reading will be no higher than the supply voltage. Since you are cranking it over, the signal will happen fairly quick so you will not see the voltage swing to power then ground. The thing you are looking for is that the signal is changing. If it is, the odds that it is working is high. If it is a steady signal, it's not working. The connector must be plugged into the distributor and the ECU for it to work. So when you tag into the wiring harness, do a fairly good job. The damage you may do, should be sealed when you are done. You could rotate the engine by hand and watch when the signal turns on and off too.

One you determine that the signal is coming out of the ignition distributor, then you need to check the signal out of the ECU to the ignition coil. Basically it will do the same thing but may have a higher voltage reading. Maybe in the range of 20-60V but I really do not know. The signal will only occur when the engine is cranking. So watch your volt meter and see what reading there is. If there is none, you probably got issues with the computer [because you already determined there is a cranking signal to the computer from the distributor].

Once you determine there is a signal at the coil, that leaves just the amplifier at the coil. Remember, these used to be replaceable, but the newer coils have them built in so you really can't. If you purchased a new coil, then it probably has a new amp too.

I always test coils with a test light. I stick one end on the power side and the other end on the trigger/point side [1 on the coil]. When the engine is cranking, the light should flicker. It will light up when there is ground and turn off when there is no ground [just like the old school points]. If there is no flicker and you have a signal to the coil, then the amp is bad. Typically there will be no ground if the engine is off. That is because if there was and you left the key on, the coil would overheat and burn up.

Here is the other catch. Since I do not have a wiring diagram in front of me, the distributor signal may go to an ignition control unit. It does the same thing as the fuel injection control unit but it's separate. So you need to determine what you got.

Basically the distributor cannot provide a ground signal to the coil without burning up the hall effect sensor. That is why they have another control module in line of that circuit somewhere. This control module may change the ignition timing based on the engine RPM and load. In the old days, the distributor did that but times change so they took that job and gave it to another module. 

So no matter what is under the hood, the distributor sends a signal to some module/s. So test the signal at the source, then follow that signal up the chain till you find the cause. Remember, if the signal goes out of the distributor, you need to make certain the signal makes it to the control module. Do not assume the wiring is good. Just take your volt meter and back probe the wire. You may need to disassemble the connectors so you can back probe the wires.

One other thing, you need power and ground for things to work. If you do not have both, electricity will not flow and therefore nothing happens. We all take ground for granted but you need to check that early on. Ground is usually circuit 31 with the Germans. Battery voltage is 30 and ignition is 15. 

Quick wrap up, check the signal at the distributor, if it is ok, go up the chain till it is not ok. If it is all ok all the way up the the coil, then the coil is bad.

Never assume new parts are good. New means Never Ever Worked. Bad new parts really screw with technicians. That is why I believe in tests. Make a test, follow what the test results indicate.


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## Blazius (Nov 2, 2018)

Butcher said:


> I do not have a wiring diagram in front of me. They're all loaded on my old laptop and I have not swapped the data over yet.
> 
> All coils work pretty much the same. There is a power terminal and a trigger terminal. Once the ground is removed from the trigger terminal, there should be a spark. It's that simple.
> 
> ...



Yup most of what you described I already did, like I said according to serivce manual. Unfortunately with wiring diagram there is a ABK one but its the 45 pin Digifant diagram which came after 1993 and my car is a 1993 june model, so it has the 38 pin Digifant. Unfortunately the wiring diagram for this car is only available in book format no digital print, I also had access to Erwin and its 130 euros to mail them, I am not spending that much on it. Also this ecu contains both the igniton and fuel system in one unlike earlier digifants.


The hall sensor is confirmed working, good supply , signal is fine and flashing. THe only thing that doesnt flash is the Coilpack Signal vs ground but apparently it should but how does a ground vs ground flash on led tester.
And according to Autodata and Vivid , the trigger to the coil/amplifier is not a ground but a low voltage frequency modulated signal. Lemme show you a pic.










This is how the ECU trigger ( pin 6 on the car) should look like vs ground at idle rpm, so at cranking RPM it should be 10 Hz or so instead of 30 Hz like this picture is for idle RPM. Unfortunately to see this I would require an oscilloscope which I do not have. The supply and continuties of the wires are good like hall sensor connection.

I also tried to fire the coilpack manually. If i apply 12v and ground to supply pins ,primary has voltage constantly, but If i apply ground to pin 2 ( the signal) nothing happens this is the same on both new and old coil. I can fire it manually if I put ground on both ground pin and signal pin at the same time and take it off the same time, but this is not the case in normal operation since ground pin is never taken off the coil.


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## Butcher (Jan 31, 2001)

Without a wiring diagram, it's really hard for me to get what you are doing. Like what is a ABK? Not certain about Audi, but cars usually made for California had fuel systems more strict and they usually had different fuel systems. I know my wife's 91 Cabriolet has a Digi I set up because the California law said it had to have a check engine light and Digi II did not have the capability. Maybe that is the reason for your differences.

What year and model is the car. One way to know the year of the car is by the VIN. The 8th digit is the year. A 93 would be 'P'. 

You really do not need a scope. I have one, but with a little common sense, you do not need it. I've found that is if the signal is bad enough not to run, the signal is bad enough to see with a regular digital volt meter. 

I'll try and get my wiring diagrams out of the older laptop today.


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## Blazius (Nov 2, 2018)

Butcher said:


> Without a wiring diagram, it's really hard for me to get what you are doing. Like what is a ABK? Not certain about Audi, but cars usually made for California had fuel systems more strict and they usually had different fuel systems. I know my wife's 91 Cabriolet has a Digi I set up because the California law said it had to have a check engine light and Digi II did not have the capability. Maybe that is the reason for your differences.
> 
> What year and model is the car. One way to know the year of the car is by the VIN. The 8th digit is the year. A 93 would be 'P'.
> 
> ...


ABK is the motor code , its basically a 2L 8v but not CIS injection but fully electronic Digifant. As I said wiring diagram is available but only for the newert digifant ecu which has 45 pins , but its is 99% the same, except that pin assignemnts are different like the trigger to coil is Pin 6 on the 38 pin, and it is number 7 on the 45 pin one.

https://www.s2-audi.co.uk/workshop/schematics_abk/abk.htm


https://www.s2-audi.co.uk/workshop/schematics_abk/abk_p5.png - ignition part the one we are interested in.


So yes, even with regular multimeter the trigger signals just says 0 volts but as I showed the oscilloscope pic there should be a spike and even the multimeter is low quality and slow, it should still show up but nothing does, which after 2 weeks means my ECU is the culprit but as I said there is no physical damage done to the components inside it, can post pictures if you want.

As for california differences yes, I believe your cali cars had the same ecu that I got , Digifant 1 with 38 pins, but im not from the US so cannot confirm that.


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## Butcher (Jan 31, 2001)

Thanks for clarifying the engine number. VW has a lot of numbers and not all of them I know or made it to North America.

I suspect that the ECU may be at fault since there is no signal coming out of it. If you unplug the coil, did the signal come back? If it did, the coil may be at fault since it could short out that signal wire. 

It is my experience that ECU's do not fail often. Because of this, I spend a lot of time proving that the ECU is the only option. The ECU must have power to it [circuit 30, 15, and 31]. There may be more than one circuit 15 too.


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## Blazius (Nov 2, 2018)

The signal is not there at all, since I tested with the coil unplugged, and it just has 0v vs ground when cranking. Also I think i figured out how this coil works, the primary seems to be always live for some reason it measures around 7v between terminal 1 and 15 on the coil( it also heats up a lot even with just ignition on since its constantly on), which means the transistor in the output stage isnt used a switch to ground but rather amplify the current from the collector to the emitter, which means if it never receives the waveform shown above to the base it will never amplifiy the voltage/current and primary is never going to have enough energy when it collapses, but as I said I am not sure how since the coil is always grounded, and sadly I cannot tell from the wiring diagram picture above if it uses a NPN or pnp transistor since the image is too low quality. 
I am going to try manually fire the good known coil and stage by applying the same kind of waveform using a 4v supply and proper current limiting resistor.

As for the ECU supply, it seems to be all good, 30 relay ( known to fail) is fine, all the pins to ECU are fine.


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## Butcher (Jan 31, 2001)

Blazius said:


> The signal is not there at all, since I tested with the coil unplugged, and it just has 0v vs ground when cranking.


What happens if you tested it with power? Put one lead on the battery power and the other lead on the signal wire.


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## Blazius (Nov 2, 2018)

If i do that then yes it flashes, just like the hall sender checking (hall sender is checked the same way)


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## Blazius (Nov 2, 2018)

I've literally tried everything every scenario but it does not seem to work. I dont get why the primary is live all the time in this application. I forgot the say when it had LPG installed the trigger signal was directly taken from the hall sender pin 2 ( signal) , so I've tried that way too but nope does not work. 

The only way I can get the coil to spark manually too is if I ground both pin1 ( ground) and pin 2 ( signal) on coilpack connector at the same time and take it off at the same time ( obviously quite fast , replicating a turning engine) . I tried applying around 3 volts to the trigger pin the same way, nope does not flash, tried applying ground to trigger, does not work only the method above.

I swear I am a stage of desoldering the output stage and using a proper transistor to ground the coil , like 99% of coil works using the hall sender signal to activate, its frustating the hell out from me, I am not new to tuning/cars/ mechanic stuff but I never ran across somethign like this.


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## Blazius (Nov 2, 2018)

Bump, still chasing this and its annoying me every single day.. I even built a custom power stage driven directly off hall sensor, and the car started up with it but died after 1-2 sec, because the transistors got too hot, eventually one burned up. So with second version I went with a mosfet instead of a darlington and it works on bench just like before, but I managed to kill 2 hall sensors with it... So currently I have to buy a new hall sensor but I really need to get the car working properly.... I might just bite the bullet and buy a new ECU.........


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## Butcher (Jan 31, 2001)

I'm still trying to get my wiring diagrams to this computer. Until I see what you are doing, it's hard to truly understand what you are doing. 

Sadly, I'm real busy keeping my clients on the road.


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## Blazius (Nov 2, 2018)

Well, like I said finding a wiring diagram for this exact car will be difficult since its only available in book format , but if you do manage to find that would be a mircale. ( I had access to Erwin , ELSA and its just simply not available unless your order it) The link that I posted is applicable like I said but the pin assignments differ slightly on some items. The only that could be wrong is the ECU so I am going to get one from breakers, however help would be still much appreciated. If that wont work then I dont know....


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## Blazius (Nov 2, 2018)

So I replaced the ECU too and still the same issue, quite unbelievable. 











This is the test that fails, but like i said it works vs battery +. Bentley states that if that happens replace the ecu, but like I said just done that after 2 weeks and still the same issue.


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## Blazius (Nov 2, 2018)

Bump, still chasing this...


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## Blazius (Nov 2, 2018)

Issue still present...


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## Butcher (Jan 31, 2001)

Until I get my ETM's out, there is little I can offer for help. I try not to work on assumptions I have to have facts to help. 

The system you are trying to diagnose is fairly simple. The distributor sends a signal to the fuel computer [low current hall effect]. That signal is modified and to change the timing by the fuel computer. That signal is sent to the ignition control unit [part of the coil]. That signal is amplified so the coil can fire. If there are three wires to the oil, one is power, one is signal, and the other is the coil ground. The coil ground should flicker when a test light is put on the power and ground connection on the coil. If it does not, then the signal wire should be tested. If there is a signal [probably square wave], then the ignition control unit/coil is faulty. 

It's that simple. Many times mechanics run into issues because the parts they are replacing are assumed to be ok. New parts are just that, new. New parts do not mean they are good/working parts. 

I had a similar problem with my Digi 1 91 Cabriolet. It took me a few minutes to gather the information I needed and a phone call to confirm my findings with a friend. I was in a parking garage in Reno, Nevada and I live in the Seattle area. All I had was a Fluke volt meter and two wrenches. I checked the distributor signal, there was a value. Then I checked the ground signal at the coil, there was none. I checked the signal wire at the coil and found there was a signal. Done, needs an ignition control unit.


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## Blazius (Nov 2, 2018)

Butcher said:


> Until I get my ETM's out, there is little I can offer for help. I try not to work on assumptions I have to have facts to help.
> 
> The system you are trying to diagnose is fairly simple. The distributor sends a signal to the fuel computer [low current hall effect]. That signal is modified and to change the timing by the fuel computer. That signal is sent to the ignition control unit [part of the coil]. That signal is amplified so the coil can fire. If there are three wires to the oil, one is power, one is signal, and the other is the coil ground. The coil ground should flicker when a test light is put on the power and ground connection on the coil. If it does not, then the signal wire should be tested. If there is a signal [probably square wave], then the ignition control unit/coil is faulty.
> 
> ...



I know that and I understand that. But like I said and done, everything that could affect the system was replaced and I am not buying more of them parts, specially not the ECU regardless if its spitting out the control voltage or not because I know for a fact thats its good. The wires are good too they have continuity , replaced ground directly to battery battery nothing. The only that I am willing to buy is a new coilpack again,, even though I have a BRAND new one. Didn't just replace parts randomly they were all tested in proper order YET it's still not good. 
I also understand this is bit alien to you guys because you did not get this system exactly so some of the things you describe dont apply but its allright since I am not a newbie, but unfortunately there is no better/other place to ask about this really.


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## garryt (Dec 22, 2016)

Blazius said:


> I know that and I understand that. But like I said and done, everything that could affect the system was replaced and I am not buying more of them parts, specially not the ECU regardless if its spitting out the control voltage or not because I know for a fact thats its good. The wires are good too they have continuity , replaced ground directly to battery battery nothing. The only that I am willing to buy is a new coilpack again,, even though I have a BRAND new one. Didn't just replace parts randomly they were all tested in proper order YET it's still not good.
> I also understand this is bit alien to you guys because you did not get this system exactly so some of the things you describe dont apply but its allright since I am not a newbie, but unfortunately there is no better/other place to ask about this really.


you in the uk???


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## Blazius (Nov 2, 2018)

Nope, in Europe though yes.


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## garryt (Dec 22, 2016)

:thumbup:


Blazius said:


> Nope, in Europe though yes.


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## Blazius (Nov 2, 2018)

Why though?


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## Butcher (Jan 31, 2001)

I've been where you are at. You need to get the idea that everything is working correctly out of your head. There is a problem and you are failing to find it. The tests you are doing or the parts you are replacing are faulty. It's your fault and not the car. 

Don't take this personal. I've been down this road more often than most. It was my job for 20+ years to fix Mercedes that the others [including their engineers] could not. If everything was good, there would not be a problem. Everything is not good and you are not testing it right. Once you wrap your head around this, then you can get back to testing. Every time I got painted in the corner, I had to look at myself and ask myself why I cannot fix it. Telling myself that everything is working right but the problem is still there is wasted time. 

There was only 1 Mercedes I could not fix. The factory support was stumped too. After 20 hours of diagnosis, we had to shot gun parts and since it was customer pay, the client pulled the plug. They pulled the plug since I could not assure them if any part I replaced would fix it and the parts I wanted were coded for their car and they could not be put back on the shelf. 

If I have a chance to play with my wife's car, I will. I will post my results and try to get some pictures.


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## Blazius (Nov 2, 2018)

Butcher said:


> I've been where you are at. You need to get the idea that everything is working correctly out of your head. There is a problem and you are failing to find it. The tests you are doing or the parts you are replacing are faulty. It's your fault and not the car.
> 
> Don't take this personal. I've been down this road more often than most. It was my job for 20+ years to fix Mercedes that the others [including their engineers] could not. If everything was good, there would not be a problem. Everything is not good and you are not testing it right. Once you wrap your head around this, then you can get back to testing. Every time I got painted in the corner, I had to look at myself and ask myself why I cannot fix it. Telling myself that everything is working right but the problem is still there is wasted time.
> 
> ...



I understand and respect that. Basically thats where I am at now. It is clear what was happening but like I said according to factory service manual I have replaced the necessary part that would contribute the issue yet the issue is still but I can confirm that part works correctly as it was tested in a different car.
Either way I am currently waiting for a new coilpack connector so I can replace this botched conversion/splicing , as I have found out recently intermittently it was causing issues.

Also I dont believe that issue is lying with the factory car itself but a modification of it down its lifespan. Like I said it has many things retrofitted and even though I tried resetting everything back to its factory state who knows what has been touched that is not visible without pulling the car apart.

Either way once I get the connector and wire it up , I'll run some tests again and report back. Though the longass shipping on it is annoying me too..


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## Blazius (Nov 2, 2018)

So update,

While waiting for connector went ahead and tested it(again) with bare wires which gives even less of a chance of a fault. 

The bentley procedure to check which I posted above always fails. Testing the trigger signal vs ground there is always 0 volts on there , it does not ever show a positive pulse, even though bentley says it should and waveforms from multiple auto repair programs too.

BUT if I put the positive lead ( of multimeter, test light whatever) to positive power wire ( switched 15) and negative lead to trigger wire, it flashes , which means it sends a switched ground pulse instead of a positive pulse OR it does the same thing but the positive pulse peak is missing only the ground part is coming through, but this is not according to specifications/manual.
( Exactly the same outcome when you asked before ).

So how to proceed in your opinion.


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## Butcher (Jan 31, 2001)

I'm trying to get a recently purchased Vanagon ready to go on a vacation for a client. They're leaving in a few days. So I have not had time to check my wife's car.

You are performing a test against the positive but that does not mean much since you do not have a reference to what it's suppose to be. So is it a good test or not. Right now, it's worthless information. 

The test Bentley [again, I absolutely hate to be wrong and I rarely assume since it just leads down the wrong path] says is to use the ground pin. The test is measuring the power signal and you are not getting one. Sounds like that is the issue. Your test is showing it's getting a ground signal but the computer does not care, it needs a power signal. Does the connector need to be plugged in? Your car is old, but with the newest cars, most test must be hooked up or the computer may remove power/ground because it 'sees' it unplugged. If Bentley says to have it unplugged, maybe it's true but I would perform the test plugged and plugged in. 

I'll do my best to make those tests today, but I do not want to look at this young family and say you're not going on vacation. I certainly do not want to get a call saying the Vanagon died too because of my hastiness.


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## Blazius (Nov 2, 2018)

Butcher said:


> I'm trying to get a recently purchased Vanagon ready to go on a vacation for a client. They're leaving in a few days. So I have not had time to check my wife's car.
> 
> You are performing a test against the positive but that does not mean much since you do not have a reference to what it's suppose to be. So is it a good test or not. Right now, it's worthless information.
> 
> ...



Bentley says to perform test with connectot unplugged so its perfectly fine to have it floating and yes ofcourse you would think thats the issue. But then it says to replace ecu if wiring is good, which it is ,checked continuity etc all according to bentley procedures , and also replaced ecu (and the ecu was pulled from a working car, so i can deffo confirm that). And yes ofcourse real life tskes priority, i would not expect it otherwise.


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## Blazius (Nov 2, 2018)

So update again..


I got the car to fire the plugs and start somehow using a newer style COP coilpack, I made a circuit that converts the ground pulse from the ecu trigger to a 12v positive as thats what this smart coil works with and yes it fires, I made a long threaded screw with SAE connector at the end so I can connect it to the distributor and car starts roughly, and when it does there are misfires and eventually dies, trying adjusting distributor etc but does not really help ( even though its bang on anyway), but I'll try sorting it out maybe change back to old plugs because they have less sparkgap and who knows how strong these coils are vs the stock coilpack.

If I wont get it running soon I might have to scrap the car, its been 2 months really, I cannot continue with my main build cause of this things and its very very annoying. 


Anything new on your side Butcher?


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## Butcher (Jan 31, 2001)

I will be working on my wife's Cabriolet Sunday to replace the valve guide seals. I will perform so tests and give you the results on a good running engine. 

Stay tuned.


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## Blazius (Nov 2, 2018)

Aight cheers, but is that car a californian car? Else you will have the sepearate ignition module and stuff, only cali digifant is similar :/.


EDIT: Oh yeah, forgot to say , I knew some people reported their issues got fixed by replacing / resoldering their nr 30 relay ( power supply). Initially I didnt take the relay apart because like I said it passed all bentley tests including the connector too. Well 2 days ago I took it apart and sure enough there were 3 dry joints, which I resoldered( I resoldered all of them anyway) they are nice and shiny now, also purchased a new ignition switch - sometimes the starter would disengage while starting or engage while just switching ignition on ( but not starting) for half a second or so, hopefully this fixes that issue.. if not I really think something is shorted and somehow its turning the starter on for a sec without switch being turned to start lol. Havent had time to check yet.


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## Butcher (Jan 31, 2001)

It's a Digifant I car, yes, California. 

The coil has three wires. Power, ground, and signal. The power and ground is 12v. The signal wire is green/black and is located in the middle. It has a 1.6V reading when the engine is running [at idle] and a .02v when the engine is off [key on].









The distributor has 3 wires also. Power, ground, and signal. The signal wire is Green/White and is located in the middle. The power is also 12v. The signal wire is 7.3v while running [at idle] and 11v with the key on, engine off.









I did not move the distributor to see if the signal changed when the trigger lined up. I suspect it would since it's a hall effect sensor. 

I suspect that the square wave that comes from the distributor goes to the EFI ecu. That information gets changed and modified. That signal is then sent to the ignition coil. That signal is normally grounded and the ground is removed when the spark needs to occur. The EFI controls the ignition timing as well as the fuel injection. 

This what I was trying to say but I'm certainly not the best at explaining myself. I hope this additional information helps. Again, both the distributor and the coil have 12v. I did not bother hooking up my scope to insure the signal was indeed a square wave. In my book, it just makes sense that it is.

When I was in Reno with no spark, a quick test showed I had a signal out of the distributor and one going to the coil. The only thing left was the ignition amplifier that attaches to the coil. The ignition amp changes that EFI signal for something the coil can use. Now you can buy a coil with the amp built in. I was able to buy the amp and got home. I put a good coil/amp unit in because the new one I purchased would cause the tach to jump when the ignition key was turned on. It was a matter of time before that would fail.


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## Blazius (Nov 2, 2018)

Yep.

My coil has 12 and ground, hall sensor has ground and 12v , and signal goes out to ECU(confirmed), it is like you say, gets modified based on coolant temp and dwell time and stuff and gets sent to the coil.
Now like I said and showed and your test now confirms , there should be a positive peak on the signal square wave, that is missing on mine, only the 0v ( ground) is present. So I am unsure why the ECU does not send the positive voltage down the wire, the only explanation I think of is that the wire is grounded somehow , but it shows no continuity to either positive or ground. the ECU is confirmed to be good, taken from a running car. 

I will see if there a positive voltage on the signal again after I fixed up the ecu supply relay and cut off the broken connector( a while ago) tommorow, since I didnt get a chance today because I was charging the battery.
I assume you tested the signal positive vs the battery negative directly or did you test on engine(itself) earth ?


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## Butcher (Jan 31, 2001)

Blazius said:


> So I am unsure why the ECU does not send the positive voltage down the wire, the only explanation I think of is that the wire is grounded somehow?


So what makes you think that the ECU puts power on the line? I would think that there is a slight bias voltage on that line and the ECU pulls it to ground. I'm certain you will agree, it's got to be one or the other but it's possible your thought is wrong. Yes, I know I could be wrong too. If there is a bias voltage, I would suspect the ICU in the coil. 

On the bright side, I replaced my wife's valve guide seals [which I did 2 years ago] because of a misfire and blue smoke on cold start ups. It's fixed, she just drove out and no blue cloud.


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## Blazius (Nov 2, 2018)

Butcher said:


> So what makes you think that the ECU puts power on the line? I would think that there is a slight bias voltage on that line and the ECU pulls it to ground. I'm certain you will agree, it's got to be one or the other but it's possible your thought is wrong. Yes, I know I could be wrong too. If there is a bias voltage, I would suspect the ICU in the coil.
> 
> On the bright side, I replaced my wife's valve guide seals [which I did 2 years ago] because of a misfire and blue smoke on cold start ups. It's fixed, she just drove out and no blue cloud.


The reason I think that is because Bentley says so and it very clearly fails that test( with the wires "floating" as in coil completely unplugged). The LED would only light up if its get positive from signal wire and the waveform info from Autodata and Vivid confirms it too.
Still didnt have the chance to test since the improvements I made and its half 9 PM again  Gotta replace sparksplugs in main build, but hopefully I can do it or maybe tonight really fast, we'll see.


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## Blazius (Nov 2, 2018)

Well just tested it again, there 0 volts on that line all the time( like before the wire if basically floating then ecu grounds it with no positive peak). Even if I can get it started with my contraption it will stop running after 2-3 seconds or so , and when it does I can hear the fuel pump prime noise( I can also hear it clearly during the motor is running the loud prime sound, which isnt the usual run sound of the fuel pump, I think) constantly going. Whatever I do I cannot it get to run reliably, and its very very very annoying , it has been 2 months now.. Without the MAF it starts a bit easier but it does the same thing.

I have confirmed that the ECU pulses the injectors , does not keep them flooded ( usual digifant issue).

Just for **** and giggles I am going to put my og coil back and see if I get a spark now ( very unlikely but I'll do it anyway thats how frustated I am).

Yup , no spark with either OG coil or new coil on factory like setup  I love doing the same stuff expecting a different outcome


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## Butcher (Jan 31, 2001)

I still have not swapped my downloaded Bentley file from my old laptop. 

Just so I can understand what is going on, use my color codes on the pictures I posted.

When you install a diode to the Bk/Gn wire on the coil, it does not flicker? Do you have a wire going to the tachometer? If you do, can you disconnect that wire? I can see if the tach is shorted out, it could kill that circuit.

Try this link and see if it applies to you. If it does, I have something to visually relate to. It's Motronic, but I do believe it applies to your ignition system. It's a bit odd to navigate, but click on next to change pages.
https://vwts.ru/vw_doc/eva2/FU03/ch3.5.html


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## Blazius (Nov 2, 2018)

I would not believe that Bentley is wrong provided I have the service info direct from Erwin.. This car has some other crazy issue... And lets not forget that the car has LPG system installed so who knows what wires are tapped into - I have the wiring diagram and it basically only shows the injectors and coil signal wire- but that does not explain why was the hall sensor output directly hooked to the trigger for the coil and it worked.. And when it died the first thing I replaced was the coil and that was without changing anything around just literally drop in but it didnt fix it. This was back in March 15...then after that came all the other stuff.

Unfortunately I cannot fire the COP coil directly as its resistance is too high vs the ecu input so all the current goes there, and if I increase the resistance toward the ecu it fires the coil fire but then the ecu does not fire the injectors and such because it senses no hall signal input( hall sensor output is 20ma nominal 40ma max not enough for both), so I'm gonna try coming up with a booster circuit so both can work.


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## Blazius (Nov 2, 2018)

So update again...


So i managed to get the car to start reliably using my converted coilpack direct from the distributor... but now I am having another ghost issue.

Basically if I remove the battery negative, and put it back and I start the car it runs fine starts with half a key.. if I shut it down and try to start it again it cranks but as soon as it would start I hear a loud bang as you would jam the starter/flywheel with a big steel piece or something, and I stop cause I dont want to break something but it does it everytime. If i remove the voltage again and put it back it starts again fine... I dont understand this bloody car..

Any ideas?


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## Butcher (Jan 31, 2001)

Does the engine lock up? 

Not certain what you mean by half a key.

Does the engine lock up? If not, I would think there is an ignition timing issue. A spark at the wrong time will stop a cranking engine.


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## Blazius (Nov 2, 2018)

Butcher said:


> Does the engine lock up?
> 
> Not certain what you mean by half a key.
> 
> Does the engine lock up? If not, I would think there is an ignition timing issue. A spark at the wrong time will stop a cranking engine.



Unfortunately i cannoy look at the engine too, but according to my dad it just stops, but if i keep the key in crank position and it will crank but it will do it every 1 second or so, sometimes i can start it up by keeping it going and maybe touching the throttle. Obviously the spark is not adjusted yet properly but for now I am taking off the starter for a grease job ( been 30 yrs) almost , then we will see.

Starting with "half a key" means that you start the engine effortlessy and nicely , a car does not need much cranking time.
Also i saw your last post today only sorry bout that.


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## Blazius (Nov 2, 2018)

So update after health issues and stuff... The car is still not running right and right now its non running again. I got it running somewhat using my trigger circuit and newer coil onplug coilpack but the circuit always dies after a while( few days).... I just dont get this POS.

Everything was replaced on this car that could contribute to this issue, I dontget why is there no proper trigger signal preset only the grounding pulse. I got it so i can work on my daily but I couldnt do f*ck all since bloody May( since I bought this thing)... if there is so no solution I am going to have to sell it somehow after spending almost as much the car itself.. I know it was cheap but man it isnt a pleasant experience with the B4 so far. 

Please if you have anymore ideas write them.


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## Butcher (Jan 31, 2001)

Not certain what to add. Obviously you have a problem and you mention that the parts have been swapped out. Did you pin out the wiring harness?


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## Blazius (Nov 2, 2018)

Pin out ? I have not done anything to wire harness except check every single pin (38 of them) for continuity and short to plus or negative and they all came out good... I am very frustrated as you see.


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## Butcher (Jan 31, 2001)

Short together? If two wires are shorted together, they will pass all resistance tests but if you never check to see if they are shorted together, then you'll never know. 

Not certain what else is left.


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## Blazius (Nov 2, 2018)

Ah yes I have checked if the 2 pins have continuity to the same end and they didnt if I remember right. Currently im working on a revised trigger circuit for the COP coilpack, as last resort 10 days left until insurance expires.


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## Blazius (Nov 2, 2018)

So update on this....


So like a weeks back, I decided to go over everything and again everything checked out except the coil like before.. so I bit the bullet and got a new coil.. Well guess what it worked to my surprise lol

Now I do not actually know if the part was bad from the start or I damaged it when I hooked it up like original coil was done ( and it worked somehow lol??). safe to say I am not buying a magnetti marreli part again( knew they were bad before but it was the cheapest so yeah)

So now I am cleaning the car, doing some stuff on it to get it ready for inspection, pay for insurance so I can have it running on road so I can continue the works on my proper daily project.

HOWEVER, I still have 2 main issues with the car. 

1. The oil pressure light is on at cold starts , goes away on hot idle , comes back on any revving. 

- First things first, obviously I have checked the oil pressure... Absolutely fine, over 5 bar on cold start, and revving it goes above 6 bar, same thing with hot, 1.5 barish idle , any revi 2.5+ bar. So I obviously replaced the main pressure switch which is know to go bad on these, however the issue is still there, what could be the cause of this.

2. Reversing lights dont work. 

- When I bought the car they were working, they stopped working sometime I dont know when. I didnt go to into detail on this yet, could just be a bad bulb ( on both sides? unlikely) or something else. I have noticed though that front or rear fog light bulb backlight indicator ( on the centre console) is on when I turn the lights on even though they arent on, so I wonder if they are on the same circuit or it coulld be reversing switch on the transmission itself, will check this issue too but its not priority atm, just wanted to mention it see what people think.


All in all , still thanks for help or the thought atleast, I am just glad its sorted for now.


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## Butcher (Jan 31, 2001)

New parts are always assumed to be good parts. The biggest fear from mechanics. That is why I've always believed in diagnosis. If the diagnosis is sound, follow it. I went through 4 brand new AMG instrument clusters on a W220 while working at the dealership. I had many engineers thinking I was ruining them or did not diagnose it correctly. In the end, it was Mercedes selling junk. The warranty clerk was not to happy and neither was the claim 

*N*ever *E*ever *W*orked.

The oil pressure system is simple. One switch works at low RPM, I believe that is grounded if the pressure is too low. The other one is the high RPM switch. I believe that is grounded when the pressure is correct [too low opens the circuit]. Make certain the correct wire is going to the correct switch. Make certain that wire is correctly routed all the way to the cluster. If all the wiring is correct and the proper signals to the cluster, it would be the cluster causing the problem.


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## Blazius (Nov 2, 2018)

So I replaced the top one circled which is the main switch, but there is one under the heat exchanger /housing which I cannot identify , I assume its the low pressure switch or oil temperature sender. The issue I cannot find either of these on ETKA ( well I can but it does not seem to be that.)

I have not looked at the cluster wiring yet, but will.


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## Blazius (Nov 2, 2018)

So I got it to pass inspection , yay, means I can actually drive it on the roads now, which means I can start tearing the b5 down.

I've noticed though its super slow, guessing 2.slow applies very well or maybe its just the DBC pedal, but still lot slower obviously since I am used to tuned decently fast car, anyway...

I figured out the reversing light issue is actually a cable issue in the trunk, the cable is broken at the hinges obviously, already bought replacement wires to fix that issue. As for the oil pressure light, the red circled one above I noticed that wiring/connection was kinda broken but I dont think it was the issue, however I will crimp new connector and test it, if not that sensor needs to be replaced I guess, however I am still not sure what kind of sensor it is, and what is the part number for it ( for the first time ever lol).


Also looking into changing the oil ,even though it was done recently, what kind should I get, I've seen people recommending 20W50 etc claiming these engies love thick oil , doesnt really get that cold here -15C max, and surerly will go for 50 weight if they like that but maybea 10w50 or something? 

Cheers.


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## Butcher (Jan 31, 2001)

I like synthetic and change the oil at longer intervals to save money. I also like the MANN oil filter W719/30 designed for synthetic oils and longer changes. I also use 10/60W Liqui Moly oil. I'm old school and like thicker oil.


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## Blazius (Nov 2, 2018)

Well.... Time for a bump again..

So few months back I got the no spark issue fixed but the car was always a tad too loud, so I couldnt drive it on the road. This week I decided to take it to an exhaust shop to get it fixed, needs new silencer, and final silencer too, and a fix near the cat..

I always noticed the car was very slow IMO ( maybe its just the difference between my tuned car and this) but like something was not right. These days when I drove on overrun/off throttle it was banging like crazy, backfiring constantly like a rally car with ALS, and I ignored it tried not stay off throttle much.
Well anyways, when I went to get the parts for the exhaust , drove like 100m from shop , and I felt the car not going/lost power for like 3 seconds, I tried flooring it and I let off the throttle, oh boi what a choice that was... It backfired massively like an arty cannon, blew up the rear silencer , popped off rear bumper on left side, ofcourse I got pretty scared thought I threw a rod or something but it was so bloody loud. Thankfully it still started but couldnt drive it ofcourse with open exhaust.

So I had to leave the car there( I was planning to anyway since they only fix it up on monday), but there is still some gremlims with this car:
1. It has no lambda sensor atm - would be useless anyway, got a leak right at the flange which is getting fixed, but since there is no lambda, the car runs richer in safe mode ofcourse, but regardless it shouldnt be constantly popping on overrun like a rally car, that is only possible if the car is still injecting fuel when im off throttle which I am not sure why it does- unless the TPS switch is broken and doesnt know its on closed throttle, regardless why did it loose power/cut spark...
2. Instrument cluster does not do anything, but it was working literally 2 days ago, after 1 start it just decided to not work, still got illumination and blinker function on it tho, just no gauges at all. Probably a blown fuse(nr 15 if i remember right) but that does not happen without a short. Another thing like I mentioned before the oil light was still constantly on, which is probably caused by the picture in my last post in this thread above^.
3.When I turn igniton on the wipers do a wipe even when the switch is in normal position, this stopped after the instrument cluster stopped working
4.Hard start when engine hot - takes like 5-10 seconds of cranking to start the car when the engine is hot...

Coupling 2 and 3 together I am still fairly sure there is a short, linking back to original thread ... Also I dont know if it caused the power loss , probably like a spark cut which led to the explosion , since the injectors work regardless if the spark is there on Digifant. There is nothing but issues with this car, all I want it to be is a backup car to drive 6km / day half decently, so I can continue on my B5 (yes still couldnt do anything)
Appreciate any comment, thanks.


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## Butcher (Jan 31, 2001)

When you have that many issues, I find that it's best to focus on the problem that you can access the components easiest. 

You are correct, spark works all the time, but the fuel should be shut off on decel. 

Power starts and ends at the battery. Many people forget the ground side of things. Not a bad idea to perform a voltage drop early on. Building a firm foundation helps with a sound diagnosis. Assuming the ground side is ok, has really screwed a lot of people. 

Sorry, not much help.


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## Blazius (Nov 2, 2018)

Butcher said:


> When you have that many issues, I find that it's best to focus on the problem that you can access the components easiest.
> 
> You are correct, spark works all the time, but the fuel should be shut off on decel.
> 
> ...



Any comment is appreciated dont worry  

Another thing I forgot to mention back when I bought the car and scanned it I think it had a throttle position sensor error short to positive or ground cant remember. Anyway I cleaned the connector back when I was searching for the no spark issue.. Now ofcourse if the ECU does not know that the throttle is closed on overrun, it would still be injecting fuel , and it couldve injected so much fuel that the AFR was so rich it couldnt make a combustion leading to the blowup in the exhaust. I dont know for sure if this was the case I am just speculating since I cant even remember before the incident was I on throttle or not.. All I know is I tried pressing it to go, and felt that it didnt react at all, then pressed it even more , still nothing then let off completely and then boom.

Anyway car has been left at the exhaust shop, I'll be picking the parts of silencer up tommorow to recreate the whole exhaust and hopefully I can drive the car home for diagnostics, but I'll try to scan it there tommorow...Wish me luck.


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## Blazius (Nov 2, 2018)

So, went to city , got the exhaust all fixed up.. When we started it to look under to check for leaks it stalled in about 2 mins. Restarted backed out, guess what , it died on the road, and couldnt restart it again ( PTSD).

Got the codes scanned.. My suspicions were right. 4 codes ( 1 for the missing O2 sens ignore that):

00523 - Intake air temp sensor -34-10 no elaboration available - short to ground from what I've gathered... 
00552 - Potentiometer for Air Flow Meter -34-10 no elaboration available - same thing..
00518 - Throttle Position Sensor -34-10 no elaboration available - again same thing.

So yeah this is probably a short, caused the TPS pos and the maf to drop out, the injectors prolly stayed on a few ms, leading to the explosion in the exhaust, but it seems to affect the spark circuit too because it does not wanna start up(checked tb angle / maf readings with vcds and they were reading okay, bloody intermittent things...), so either dizzy again or ignition transformer.. unfortunately I didnt have my test light or multimete with me. But I just hope they are okay, dont wanna particularly rebuy the same parts again..

As for the instrument cluster, as I thought the fuse is burned( nr12 on my car) and its a 15 amp fuse.. that doesnt break from a small short. This also means that there are multiple shorts/errors because this fuse was broken / open circuit for the ~50km that I've driven before the incident..


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