# CIS-Lambda: car starts then dies when coldstart turns off



## polskipolak (Aug 22, 2003)

I am working on a 1986 Scirocco 8v. It is equipped with CIS with an oxygen sensor and a frequency valve at the fuel distributor (CIS Lamda AFAIK). 
At first I was unable to start the car at all . I was able to fix the problem by checking the connection to the coldstart. The terminals inside the connector were spread too far apart and they werent making contact with the connectors on the valve. I pushed them back together and it fired up...then died when the coldstart stopped recieving power.
Here are some videos of whats happening:
http://www.youtube.com/watch?v=2pmIrD1YI6Y
This first one is what happens when I turn the key and let it start on its own.
http://www.youtube.com/watch?v=VfyLZkNpmAo
In the second one, I gave it gas after it started, then eventually it just died off.
Here are some notes on various things:
The injectors are spraying when I lift the airflow plate manually.
I cant use a real fuel pump relay to start it. I have to use a jumper cable or else it wont start at all. Ive tried 2 relays so far, still have 2 more to try out. 
One thing im confused about: When I turn the key to the on position, without trying to start the car, should I be able to hear the fuel pump come on? or does the pump come on only when the key is turned to the start position? I dont think it does either with a real relay.
About the frequency valve: If I unplug that, would the car function as if it had a fuel distributor without it, or does it still do something to the fuel flow when its not connected? Im asking, in case my O2 sensor may be dead.
Besides that, I think there could be a vacuum leak somewhere or I need to adjust the air/fuel mixture with the 3mm screw. Any thoughts on if it could be something else?
Thanks for reading, and enjoy the videos!


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## deer_eggs (Oct 4, 2006)

*Re: CIS-Lambda: car starts then dies when coldstart turns off (polskipolak)*


_Quote, originally posted by *polskipolak* »_I
One thing im confused about: When I turn the key to the on position, without trying to start the car, should I be able to hear the fuel pump come on? or does the pump come on only when the key is turned to the start position? I dont think it does either with a real relay. 


With a relay installed, you should hear the fuel pump come on (for about 2 seconds) as soon as you turn the key to the "run" position. With a jumper installed, it should be on whenever the jumper is installed.
From your description, _maybe_ your relays aren't bad - they're just not getting the "switched power". If your other two relays don't work either, give that a try.

_Quote, originally posted by *polskipolak* »_
Besides that, I think there could be a vacuum leak somewhere or I need to adjust the air/fuel mixture with the 3mm screw. Any thoughts on if it could be something else?


Quite possibly a vacuum leak. With someone cranking the car, spray starting fluid on all possible leak-points (intake manifold, intake tube, TB, vac. lines, brake booster line, etc). If it runs for a second or two, than there's your leak! 
edit: sorry if any of this is wrong, please jump in and correct me!


_Modified by deer_eggs at 8:54 AM 6-3-2007_


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## polskipolak (Aug 22, 2003)

*Re: CIS-Lambda: car starts then dies when coldstart turns off (deer_eggs)*


_Quote, originally posted by *deer_eggs* »_
With a relay installed, you should hear the fuel pump come on (for about 2 seconds) as soon as you turn the key to the "run" position. 

Run position meaning the point before turning it even further to actuate the starter? If so, then it doesnt come on for sure at that point.
I just went out and did this test again. One of the relays does work when the key is turned all the way to the start position. So I guess the relay isnt the problem. Ignition switch maybe? I remember testing it in december of last year, maybe it just recently failed, ill test that soon too. 
Ive also read that theres a signal going from the coil to the fuel pump relay which can disable the pump if there is no signal that there is spark, Ill be checking this as well.


_Quote, originally posted by *deer_eggs* »_
Quite possibly a vacuum leak. With someone cranking the car, spray starting fluid on all possible leak-points (intake manifold, intake tube, TB, vac. lines, brake booster line, etc). If it runs for a second or two, than there's your leak! 


I will get some starter fluid this week and try this out. Ive read that throttle body cleaner can be used for this also?


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## atoson (Dec 29, 2002)

*Re: CIS-Lambda: car starts then dies when coldstart turns off (polskipolak)*

If you don't have the fuel system pressurized the pump will run for 2 secs then stop. It works right after ignition is achived and flow of fuel is demanded by the injector. Now the reason you need a jumper is when you are testing the fuel system with a pressure gauge so you'll know how much fuel flows in the system without the engine running. 
On cold start up you should check whether (1) the aux air regulator is fully open, (2)that the fifth injector squirts the extra fuel then shuts off. This is the first general requirements in able to achive start up. Although considering that all your timing marks are in the general area it should be. 
Once it is warmed up, the first 2 devices returns to it's default position, closed and not injecting fuel. Don't mess with your distributor plate adjustment without a dwell meter and disconected the 02 sensor wire. There is a wire near the brake booster which doesn't connet to anything, find that and hookup the pickup for your dwell meter. This wire will send the frequency valve signals and used to read your air/fuel mixture without an exhaust gas analyzer. This is where the 3mm allen driver comes to play.


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## polskipolak (Aug 22, 2003)

*Re: CIS-Lambda: car starts then dies when coldstart turns off (atoson)*

Thanks for the explanation. 
The aux air valve was open when I was installing it, so Im guessing thats good. The cold start fires. Timing is correct also. 
I do have a dwell meter that I will use to adjust the air-fuel mixture like you said. The reason I mentioned it for starting, and I should have mentioned this, is that the fuel distributor came off a Fox, and I thought that maybe it had it set at a range not suitable for a modified scirocco. 
Would anyone be able to answer: Does the coil send a signal to the pump that tells it to continue pumping when there is spark? Could this be why the car doesnt stay running?
Overall though, Im starting to think more and more that its a vacuum leak. Im gonna replace all the vac lines soon, hopefully its not a gasket http://****************.com/smile/emthdown.gif


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## wclark (Mar 28, 2001)

*Re: CIS-Lambda: car starts then dies when coldstart turns off (polskipolak)*


_Quote, originally posted by *polskipolak* »_Would anyone be able to answer: Does the coil send a signal to the pump that tells it to continue pumping when there is spark? Could this be why the car doesnt stay running?


The CIS-LAmbda does use the independent relay with the "tach" input from the coil - to determine if it should be on or not. It is the very small tab on the relay. The relay should turn the main and transfer fuel pumps on when the igniton switch is moved to the ON position. If the relay doesnt see "tach" pulses from the coil within a few seconds of turning theignition ON it will shut off and you have to cycle thru ignition OFF to reset it. Either turning the engine over in the START position or with the engine running you will generate pulses that should satisfy the relay and keep it on. 
If a relay doesnt have the tach input (or something is wrong with the circuit inside the relay) the symptom will probably be that it will start then die very quickly. That is because it only takes a second or so to fully charge the fuel lines and that would provide fuel to the cold start valve and fuel distributor until a second or 2 after the relay shuts itself off...perhaps 5 seconds in all. By jumpering the power contacts in the relay socket you will tie the fuel pump to 12V so the engine should then start and run normally if the relay or tach input was the culprit.


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## atoson (Dec 29, 2002)

*Re: CIS-Lambda: car starts then dies when coldstart turns off (wclark)*

Keep in mind you also have a digital idle stabilizer and a control unit for the ignition that might be bad. I snagged 3 of this chips from the yard just in case mine broke. With a vacuum leak it will run unstable with fluctuating rpm's but it will continue up until the ratio of air to fuel is greater then it stumbles. It would stink like rotten eggs and irritate your eyes and nose when it's lean and fuel odor when it's rich due to uncomplete burn in the combustion stage.


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## polskipolak (Aug 22, 2003)

*Re: CIS-Lambda: car starts then dies when coldstart turns off (wclark)*

Ok thanks for those last two posts. 
Im starting to understand how this works now. So if I have my fuel pump relay jumpered, then that would eliminate that as the cause of the stalling, correct? 
So the next question would be: How does the spark ignition work? If the engine is running for a few seconds, and then there is no signal to the relay, would that cease the production of spark?
Another note, which may be hard to tell in the videos is: When its dieing, you can hear each revolution getting slower and slower. Giving it gas doesnt make it run faster as expected. Im guessing this could be because theres less and less fuel available?
As for the digital idle stabilizer, is that the valve thats attached to the passengers strut tower? with the vacuum tube attaching to the intake mani? I will look into that, thanks. 
And for the smell: After it shuts down, there is definitely a smell from the exhaust, I was thinking that it was because the car has no catalytic converter, I guess it does sort of resemble rotten eggs (I will give it a better wiff next time hehe).
One thing i thought of to try is to see if the car will stay running if I pull the airflow plate up manually. If it does, then would that pretty much indicate a vac leak? or is there another reason why the plate wouldnt rise enough? like maybe because the head is ported? cams too big?
I will be working on it in the next few hours, I will reply back with some more info later on tonight.


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## atoson (Dec 29, 2002)

*Re: CIS-Lambda: car starts then dies when coldstart turns off (polskipolak)*

Since the only way to help at this point is by VTex so I would suggest some tools you might need that I would use if I was your mobile mechanic.
Tools:
1) Fuel pump relay fused jumper wire
2) Fuel pressure guage
3) 3mm allen 
4) VOM 
5) Test light
6) Remote starter switch
7) Carb cleaner
8) Propane torch
9) Compressed air

The fuel pressure gauge will diagnose whether you have constant fuel pressure from the fuel pump in cold and warm operating temperature. It will also tell you whether the system has a leak or holds the pressure while the engine is in off position. If you have a leak while your car is sitting till the next start up then you could have a flooded cylinder. This will give you an indication if the injectors are holding the pressure since they are mechanical which uses specific spring tension to oprn the injectors.
VOM
This will help you whether you have positive voltage across the circuit connectors/connection. It will tell you if they are grounded properly. Some devices need the Ohm reader specially if they operate using heat and expands a spring when heated (Aux air regulator/ Fuel pressure regulator/Thermo time switch) giving off readings either in infinte or specific number (resistance) values.
Remote Starter
Makes starting the car easier from the engine bay while tweaking the components.
Carb cleaner
Clean parts that are dirty specially if it has any oily residue beside cooling the part down when test require cold test conditions.
Propane torch w compressed air
This will help you find air leaks in your intake system when you pressurize the intake track. With the track pressurized carefully run the flame across the track observing the flame flicker from blue to orange. Orange means contaminated air is being burned in the propane mixture of your flame. Only a real moron wouldn't use extra caution doing this and actually start a fire in the car, so use you head when you do this.


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## polskipolak (Aug 22, 2003)

*Re: CIS-Lambda: car starts then dies when coldstart turns off (atoson)*

I didnt do much tonight.
Thank you for that list of things to try http://****************.com/smile/emthup.gif 
Tommorow I should be working on it a lot.


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## wclark (Mar 28, 2001)

*Re: CIS-Lambda: car starts then dies when coldstart turns off (polskipolak)*


_Quote, originally posted by *polskipolak* »_Ok thanks for those last two posts. 
Im starting to understand how this works now. So if I have my fuel pump relay jumpered, then that would eliminate that as the cause of the stalling, correct? 
 
That is correct. However, it is possible that the fuel pump cannot deliver enough volume, due to blockage or some other problem and the symptom could be similar. Also, just be sure... with the jumper in, the fuel pumps are actually running...go to the rear and listen while the igniton is on and check after the engine dies as well.

I will try to answer these as best I can. Troubleshooting remotely is always a bit of a crap shoot.

_Quote, originally posted by *polskipolak* »_So the next question would be: How does the spark ignition work? If the engine is running for a few seconds, and then there is no signal to the relay, would that cease the production of spark?

Well if the - terminal of the coil no longer receives pulsed grounds the ignition would not have a spark. If you were to monitor the signal going to the fuel pump relay, you could see this. You description suggests the spark begins normally and the engine solwly dies which would require thatthespark amplitude degrade relatively slowly. That would be unusual and not the first place I would look.

_Quote, originally posted by *polskipolak* »_Another note, which may be hard to tell in the videos is: When its dieing, you can hear each revolution getting slower and slower. Giving it gas doesnt make it run faster as expected. Im guessing this could be because theres less and less fuel available?

This symptom is why I would look for fuel or air issues. Have you checked the operation of the frequency valve? When cold, the engine control unit should be operating this valve at around 50-60% duty cycle. If this valve were stuck or held closed the engine would be forced very lean and probably would not run. The dwell meter will tell you if the electronics is trying to operate the valve. If thevalve feelslike it is vibrating you will know the elextronics is trying to operat it and thecoil in the unit is working. The valve itself still might not be working so cracking the fuel line downstream and looking for output with the ignition on is a way to tell if it is stuck closed.


_Quote, originally posted by *polskipolak* »_One thing i thought of to try is to see if the car will stay running if I pull the airflow plate up manually. If it does, then would that pretty much indicate a vac leak? or is there another reason why the plate wouldnt rise enough? like maybe because the head is ported? cams too big?

Since it starts, I wouldnt suspect a problem with porting or the cam. A large vac leak could cause this as you would run way lean.


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## polskipolak (Aug 22, 2003)

*Re: CIS-Lambda: car starts then dies when coldstart turns off (wclark)*

Thanks for the info clark. 
I decided today to test all electronic connections first. I think ive stumbled upon the problem! but then I guess I did something and made it even worse: 
I checked the frequency valve like you suggested. I didnt hear or feel any buzzing, so I decided to investigate. It has 2.7ohms resistance, so it looks like the valve itself is good. It receives a 12v signal. But it didnt seem to have a good ground, as when I had a test light attached across the 2 terminals and cranked the engine with a fuel pump relay jumper the light didnt turn on!
So I started to test grounds and all the connections that attach to the oxygen sensor control box. Every connection was good. But then when testing the voltage coming to the control box, I found the problem! It was only recieving 4volts of power there. I went behind the fuse box and tested the same cable there, it had 12v. According to the diagram there are 2 connectors along the way, so I started testing after each one. It turned out that the connector beside the coil was messed up. There it showed up as 5volts. So I disconnected this connector, which has both the power to the ECU and the power to the frequency valve. I tested the power to the frequency valve first. It came out to 12v, then I tried testing the ECU lead, and I got nothing







So I went back behind the fuse box to see if those connections had power. And now neither of these 2 wires for the ECU or the Frequency valve has power.








I dont know what happened, I guess I fried the relay somehow, maybe I touched the lead somewhere while operating the multimeter. This is when I gave up because I was getting hungry, and now here I am!
Ill probably go back out and investigate further after writing this, or maybe not








update 9:30pm: I got it! The connection was just bad at the connector near the coil. After some cleaning the frequency valve started working, its sounds pretty loud, although I cant compare it to anything since it didnt work before, I just thought itd be quieter. 
I did all the different test for the ECU and the dwell meter shows that everything is working. 
The only problem right now: when I install a real relay instead of a jumper for the fuel pump, the car starts and dies, within 2-3 seconds. Im pretty sure someone explained this above, Ill have a look at that tommorow.



_Modified by polskipolak at 9:27 PM 6-6-2007_


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