# lambda system issues



## dubsteez79 (Jul 17, 2014)

*CIS lambda system issues*

Pretty sure im having lambda system issues with my 84 gti. The car cranks and idles well. It will also rev well at first. After it warms up for just a few minutes, when I give it gas, it will rev; but slowly, like its not getting enough fuel. When I push the WOT switch, the car revs like it should again. All this happens under no load(neutral)

When driving the car down the road its a similar story. At WOT it will pull like it should. Otherwise it accelerates slowly and sounds like its struggling for fuel. 

I was tapping on relays with the car idling and when i touched what i assume is the lambda system relay, the car died. It would crank right back up. tapped and died again. I changed it to one from my 80 vert and it seemed to alleviate the issue for a while. The issue has came back now. Im assuming I should just buy a new relay and see if the problem stays away(found another in the pullapart), but are there any other things I should be checking as well? O2 sensor looks brand new and is connected correctly. Also the relay from the 80 cabriolet has a fuse on top while the existing and pullapart one do not. I figure they should work the same? I mean it is just a relay and it has the same pins. Maybe taking the fuse/relay panel out and inspecting for corrosion is my next step?


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## volkshead83 (Feb 8, 2014)

Are you refurring to the fuel pump relay?


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## dubsteez79 (Jul 17, 2014)

volkshead83 said:


> Are you refurring to the fuel pump relay?


I guess so. That would make sense as to why the car shut off when I tapped the first one. I dont have a tech manual with a diagram of all the relays/fuses so I dont know for sure.


EDIT: After a quick internet search, the relay i changed is the fuel pump relay. Does the lambda system cycle the fuel pump on and off to change the AFR? Or does it just change the control pressure of the fuel system to alter the amount of dispensed fuel through the injectors?


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## volkshead83 (Feb 8, 2014)

Im not to sure. Im dealing alittle with this my self thats the last thing I can check becuase everything else was bench tested and the issue started with in a matter of minutes after parking the car.


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## volkshead83 (Feb 8, 2014)

I didnt have Another relay I could of checked I removed a couple unused connectors I didnt need and it ran top notch like that so im still at squar one figuring mine out. It has to be the fuel distro at this point


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## volkshead83 (Feb 8, 2014)

I didnt have Another relay I could of checked I removed a couple unused connectors I didnt need and it ran top notch like that so im still at squar one figuring mine out. It has to be the fuel distro at this point


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## dubsteez79 (Jul 17, 2014)

volkshead83 said:


> I didnt have Another relay I could of checked I removed a couple unused connectors I didnt need and it ran top notch like that so im still at squar one figuring mine out. It has to be the fuel distro at this point


I feel like it has to be something electrical. considering that it seems to run perfectly when I hold the WOT switch, which bypasses the lambda system. I feel like it has to be whatever the lambda system uses to meter the amount of fuel going to the injectors. Or does it just change the control pressure accordingly? Maybe I just need to read into cis-lambda system more...

This is for cis-e but has info on the other systems as well.

http://www.csupomona.edu/~bvnorum/cars/WSP-521-124-00.pdf


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## dubsteez79 (Jul 17, 2014)

after a quick google search of "cis lambda fuel system", I found a pdf that breaks down the system into components and explains their purpose. It seems as though my issue could be with the frequency valve. This opens and closes in accordance with o2 sensor readings to keep the AFR at stoichiometric(~14.7). Hell, the frequency valve could be gunked up or something too. It is what controls the pressure going to the fuel distributor from the best I can tell. I will mess with it/change it and let you know what happens in the coming week. 

Excerpt from pdf:

OXYGEN SENSOR
The oxygen sensor is located in the exhaust manifold and
measures the amount of unburned oxygen in the exhaust gas. If oxygen
is low (rich mixture) a high voltage will be generated by the sensor.
If oxygen is high (lean mixture) low voltage will be generated. The
voltage signal from the oxygen sensor is sent to an electronic
control unit which controls fuel mixture.
ELECTRONIC CONTROL UNIT & FREQUENCY VALVE
The electronic control unit is designed to continually
correct air/fuel mixture, based on signals from the oxygen sensor. It
sends a series of pulses to a frequency valve. The frequency valve is
located in a fuel line that connects the upper and lower halves of
the fuel distributor.
When the frequency valve is closed, fuel pressure to the
injectors is determined by a spring in each pressure regulating
valve. When the frequency valve is open, fuel pressure decreases in
the lower half of the fuel distributor, the tension on the spring is
relieved, and more fuel is directed to the cylinders.


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## volkshead83 (Feb 8, 2014)

I read that also. Ive been trying to figure out this since last week. My freq valve sounds like a mad typerighter going off. Im not sure if its becuase to much pressure or what. And odd it would just do this out of the blue. But I know the book says if you dont hear it its bad. I did adjust the system pressure down with another valve i had laying around with thinner shims. It started and idled fine tell it started getting warmer, so i guess im on the right track. I also did a leaking injector test and spray and volume test on the injectors and they are good so it has me puzzled. 
Im going to pick up another wurvtoday or tomarrow along with a 016 basic distro to convert to if all else fails and not worry about going fast anymore, since I need this car up and running. It just doesnt seem right if everything checksout and not working.


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## dubsteez79 (Jul 17, 2014)

I have another question which may sound stupid. Is the airflow plate supposed to move up and down freely? When I pull up on the airflow sensor plate, it sticks there and doesnt fall back down. all the ones i have messed with in the scrapyard fall right back down and have no "bound-up" feel at all. But these werent on running cars so I didnt know if this is normal or not. Ive sprayed it with carb cleaner from the underside with little to no change in tightness. 

If this needs to be free, then can i get to the pivot point by taking the 3 screws out of the fuel dist. and taking it off? Or is there another way thats easier?


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## volkshead83 (Feb 8, 2014)

Yeah sounds like it needs to be cleaned up some. Now if the airflow plate is hanging up around the lip of the resting position then it needs to be adjusted to free it up centered. Which was one of the first things I had checked on my bunny.


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## volkshead83 (Feb 8, 2014)

Well I consulted my dad after the samething being on cis basic now. And hes suggested that its timming or ignition distributor I guess time to check that and rule those out of the list also will check my coil and ignition.


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## volkshead83 (Feb 8, 2014)

Nope not it


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## dubsteez79 (Jul 17, 2014)

cleaned the fuel distributor and it goes down the road with no stumble now. Still fluctuates at idle. Also Doesnt want to crank hot unless i hold the throttle wide open. But it is driveable...


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## volkshead83 (Feb 8, 2014)

Good to hear


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## dubsteez79 (Jul 17, 2014)

Started stumbling again. yay....... My O2 sensor looks brand new and the frequency valve sounds working. WTF?


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## volkshead83 (Feb 8, 2014)

Hall sender was my problem I retested it warm and failed horribly bad


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## dubsteez79 (Jul 17, 2014)

Started what seems like skipping yesterday. All the plugs have fire though so I dont think its ignition related. Gotta be fuel. I assume an injector could be clogged up but just didnt have time to pull em yesterday. Could it be that trash/gunk is making its way through the fuel system a piece at the time? Thats what it seems like is happening lol. And I have been cleaning different parts of it intermittently.


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## volkshead83 (Feb 8, 2014)

It could be. If so the fuel filter should be catching it


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## ps2375 (Aug 13, 2003)

Unplug the freq valve, that will cause the system to go slightly lean. Now you can determine if it is fuel or spark. Get a WB sensor and a gauge, replace the narrow band sensor you have and set the afr for what you want and the CIS will work just fine. It also sounds like you have a hot start issue caused by a failing WUR/CPR, the only real way I have found to deal with those is to find a replacement/rebuilt one or convert to efi. After I did the latter, I never had a hot/cold start problem with my motor again. I could start it in sub-freezing temps and never have to touch the gas pedal.

The lambda system is very crude and simple, I found that if you just disable it and set the idle mixture, the CIS holds that tune from idle to 6500rpm just fine, at least it did when we ran a 16V swap in the 80' Scirocco on the CIS-L with the "L" part disabled.


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## dubsteez79 (Jul 17, 2014)

ps2375 said:


> Unplug the freq valve, that will cause the system to go slightly lean. Now you can determine if it is fuel or spark. Get a WB sensor and a gauge, replace the narrow band sensor you have and set the afr for what you want and the CIS will work just fine. It also sounds like you have a hot start issue caused by a failing WUR/CPR, the only real way I have found to deal with those is to find a replacement/rebuilt one or convert to efi. After I did the latter, I never had a hot/cold start problem with my motor again. I could start it in sub-freezing temps and never have to touch the gas pedal.
> 
> The lambda system is very crude and simple, I found that if you just disable it and set the idle mixture, the CIS holds that tune from idle to 6500rpm just fine, at least it did when we ran a 16V swap in the 80' Scirocco on the CIS-L with the "L" part disabled.


Thanks man. EFI is the way to go for sure. My toyota wagon on megasquirt cranks up within half a second no matter what the temperature is, and never fluctuates. But im trying to just get it going on the stock stuff for right now on this gti since its been checked and engine rebuilt not long ago.

I really like my AEM UEGO system(face is black now)









I cleaned out the CPR and its lines again yesterday. Also did an injector spray test and they all performed perfectly. Sprayed the same amount of fuel and had a nice spray pattern. I ALSO found that the stiff plastic line going from the fuel filter to distributor had a nice pinch in it. I replaced this with one from the junkyard. I cranked it up and ran it for a few minutes and it seems to have no problems anymore(at least for right now). I am going to drive it when I get off work and that will determine whether or not all is well.


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## volkshead83 (Feb 8, 2014)

Its all the same thing part after part wtf.


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## dubsteez79 (Jul 17, 2014)

I had it running pretty good this past weekend. I drove it 2 hours away and no problem. Cleaned out my air flow sensor and got it working free like it should have been. It was running well at that point. I drove it 2 hours back home and when I took my exit and took the car out of gear, it died. It would crank back up and keep running if I kept my foot on the gas. I think my fuel pump is failing so I have ordered another one just so I can feel comfortable that it is perfect before I **** with anything else. I may pull off the CPR and completely take it apart considering how gunked up the air flow sensor was but hell who knows whats going to make it work.


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## volkshead83 (Feb 8, 2014)

I tryed that. Have you jumped the fuel pump relay and tryed driving it to see if the pump is still running when it dies


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## rabbitnothopper (Oct 19, 2009)

get this

http://forums.vwvortex.com/showthread.php?6060634-DIY-Fuel-Pressure-Tester


use a DMM to check the test port for the dwell/duty
yes it must be an automotive specified DMM

there are 2 i would recommend which are $60


....you probally have a vacuum leak somewhere
this causes the air to bypass the air meter and gives you less fuel


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## volkshead83 (Feb 8, 2014)

Well replaced the coil. wires. Plugs. Cap. Rotor. And had to adjust the af almost all the way rich and also had to adjust the timming from factory spec. And its running and driving but alittle ruff which idk if thats becuase the cam or not but has good pickup on it. Im thinking of just saving up for cise or digi swap. Becuase this lamda and basic crap has got me alsorts of confused after checking everything over and over with all the right tools and guages and still be way off. Idk if its due to p/o or what


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## dubsteez79 (Jul 17, 2014)

CPR is clean now and all electrics looked good inside. Runs smoother but most of the problems still exist. I will have a new fuel pump in tomorrow. I wanted to get one just so I know thats not going to be an issue for a while. Ill keep the old one if that doesnt fix it.


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## dubsteez79 (Jul 17, 2014)

You should megaquirt it.  All of these problems dont exist with megasquirt. At least on what I have put it on. The only thing is that several things have to be changed on these engines to run it.


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## volkshead83 (Feb 8, 2014)

The fuel lines you have running to your fuel distributor are they the plastic kind that can kink? I just replaced my return line it had a slight kink. Im seeing if thats the issue today. It was to late lastnight to test it out plus I had a few beers so I couldnt drive it around either.


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## dubsteez79 (Jul 17, 2014)

volkshead83 said:


> The fuel lines you have running to your fuel distributor are they the plastic kind that can kink? I just replaced my return line it had a slight kink. Im seeing if thats the issue today. It was to late lastnight to test it out plus I had a few beers so I couldnt drive it around either.


At one point I had a kinked line in between the fuel filter and distributor. Replaced it and it did run better. I replaced the fuel pump Friday and it runs well...I just cant go around a right hand turn without the car dying... From some research it sounds like it could be a broken/clogged line inside the tank that goes from an internal baffle/reservoir to the tank outlet. Dont know if im going to replace the tank yet. Ill have to drop it, clean it and see if that hose can be replaced or not. My arm may be too big to go in that tiny fuel sender hole.


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## volkshead83 (Feb 8, 2014)

I read awhole back thinking about it now the gravity breather valve has a little ball inside it. I wonder if that could cuase it. Located in the right rear wheel well.it stops the car from running when you rollover. You could disconnect it and see.


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## dubsteez79 (Jul 17, 2014)

volkshead83 said:


> I read awhole back thinking about it now the gravity breather valve has a little ball inside it. I wonder if that could cuase it. Located in the right rear wheel well.it stops the car from running when you rollover. You could disconnect it and see.


I am getting a new tank in today so I will have all of this off. I will make sure the ball still moves freely in this valve for sure and remove it if i cant get unstuck.


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## dubsteez79 (Jul 17, 2014)

After I put the new fuel tank and pump in, the car ran great for a day....Although a little rich(I could smell it). I can turn right now as well lol. The next day it was going fine until on my way back from the shop. It wouldnt accelerate and it sounded like it was missing on a cylinder. I took the plugs out, and all but cylinder 4 was black and 3 was more wet than 1 and 2. Changed out the plugs(with a used bosch set id cleaned) and no change even after running it for several minutes. Changed the plug wires today and still no change. I didnt let it run much but it it didnt seem as if it was clearing out. I guess ill pull the plugs one at a time when i get home and narrow it down to a cylinder/plug. I guess I couldve fouled one plug in each set but if not that; Any ideas on what it could be? Ill pull the injectors and do another injector flow test and make sure its not fuel issues again. Any normal issues relating to the distributor to be aware of on these things?


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## dubsteez79 (Jul 17, 2014)

well god damnnit, it started breaking up when I got on the gas after cleaning all of the injectors. I got about a mile down the road and it started. Got worse from then on to the house. I noticed the injectors were only spraying about 2/3 around the 360 degrees of the spray pattern with compressed air before I put them back in there. I ordered new ones so we will see how it goes after that I suppose. :beer:


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## stija (Aug 20, 2011)

What is the frequency valve you talk about in the above quote from the pdf? Is that referring to the DPR?

From what you are describing it sounds like you are running lean. Try disconnecting your o2 sensor, and assuming that you catalytic converter works, connect a voltmeter to the sensor-side of the plug with the car running. With the engine warmed up at idle, adjust the air mixture screw on top of the fuel distributor (between the plastic round boot and fuel lines) while reading O2 measurements. When you are satisfied that the air mixture is proper, plug the 02 back in and then try driving the car. The stoich mixture is attained at .45v i think, but O2 should constantly be correcting the mixture therefore the readings will be constantly fluctuating, usually from .7 to .1. If you get a solid and constant reading, we can conclude your sensor is bad.

At WOT you are not stumbling because at WOT the DPR (frequency valve?) enriches the mixture, thus not allowing for the stumble. But at partial throttle the mixture is not getting the same amoutn of enrichment that it gets at WOT which is why you feel the car stumbling.

All of the above applies if we assume your plugs, wires, distributor, rotor, etc, are all in good working condition, and you don't have a non-fuel related problem.


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## volkshead83 (Feb 8, 2014)

Did you mess with the timming at all?


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## dubsteez79 (Jul 17, 2014)

volkshead83 said:


> Did you mess with the timming at all?


So I started messing with the timing and figured out the PO had the timing belt off one tooth.  Then got the timing straightened out. It ran well for about a minute and developed a miss on cylinder 3. I had spark. I switched the injector lines and the skip moved. Fuel problem in the distributor. Oddly enough, it would smooth out and run well under load. :screwy: I took the dsitributor fully apart and cleaned everything inside. Rebuilt it and put it back on the car. Pissing fuel in the crack between 2 distributor halves now. Any idea what sealant i need for this area? I gave up on it after that and will try some to seal it tomorrow. If this doesnt change it, I think the feed to each injector may need to be adjusted. maybe.

And also, the PO put non shrouded injectors in the car even though it is supposed to have shrouded ones. So I plugged the vac line that goes between the head an intake tube. It still has the air shrouded inserts in the head.


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## volkshead83 (Feb 8, 2014)

You need a wax sealant. I read about this in the mk1 forum about 2 months back.


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## dubsteez79 (Jul 17, 2014)

volkshead83 said:


> You need a wax sealant. I read about this in the mk1 forum about 2 months back.


Ive been looking into it a fair amount. I think I have settled on some Loc-Tite anaerobic sealant. It works up to 350F, is fuel resistant and is said to work well on machined cast surfaces because it fills the imperfections. Ill let it set overnight before I hook it back up and put fuel through it though.


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## dubsteez79 (Jul 17, 2014)

I took my fuel distributor apart completely, cleaned it and put it back together. I started the car and it runs, no leaks. It is running so rich that fuel is coming out of the tailpipe lol. I changed the number of shims in the pressure relief/residual pressure valve(see page 9 of link below) around and it never seemed to make a difference. Always mega rich. So now im really ****ed


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## dubsteez79 (Jul 17, 2014)

Anyone know the size of the 2 large o-rings for the plunger bore/cylinder?

Are the 2 small holes pictured supposed to be lined up? 

Small hole in plunger cylinder








Small hole in distributor housing


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## dubsteez79 (Jul 17, 2014)

Heres a step by step rebuild on a lambda distributor. Also read on pelican and it sounds like the 2 holes I was talking about in my previous post are supposed to be 180 degress apart...But not 100% on that


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## dubsteez79 (Jul 17, 2014)

I will finish out this thread since that was something I would have liked to seen when I was having issues. I replaced the fuel pump/accumulator/injectors/filter and cleaned out the lines and still had issues(was missing on one cylinder and it was fuel, not spark). I replaced the fuel distributor with a junkyard one from ebay. The plunger was never stuck and I think thats the only way to know if its good or not. Ran better than before. I went through my CPR / WUR completely and cleaned it with carb cleaner. I didnt replace any orings or make any adjustments to it(CPR). It would run well when under load but shut off with no pedal or load. I was having trouble getting it to idle but it was because I was trying to adjust it with the idle valves for brake booster and AC still plugged in:facepalm: After I unplugged them and set the idle I have had no issues since. Make sure your o-ring for the idle screw is good and tight or put a rubber cap over it to keep it from moving. I had that happen and cause it to stall in town. I put the cap on it and no more of that. :thumbup: 

I had the turn right/dies issue as well. Replaced the fuel tank with the spectre brand from rockauto and have had no problems. I dont take it easy on the car either:vampire:

Hopefully this will help someone in the future. Cheers! :beer:


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