# CIS Lambda - runs lean, then perfect.



## deer_eggs (Oct 4, 2006)

This problem started yesterday morning, after driving the night before in heavy rain.
The car (1986 Cabriolet, CIS Lambda) will idle rough, & run rough. It's low on power, and is hard to keep running... until you drive it down the road. after you drive about 1/10 of a mile, maybe less, the car will gain back all of it's power, and run as smooth as ever for the rest of the time that you drive it. Both fuel pumps are getting power, and the in-tank pump's screen is free of any debris. No vacuum leaks anywhere, checked with starting fluid. I even moved the intake boots around, with no change. So far, I've disconnected the oxygen sensor, with no change. The frequency valve IS buzzing. A mechanic where I work (VW dealership) said that it even smells lean.
After driving the car, & shutting it off, and allowing it to sit, the whole process starts all over. Any ideas? 
A fuel filter is ordered, and I will install that tonight to see if there is any change. I'm wondering if the CPR is going bad, allowing control pressure to be as high as system pressure?
not that it matters too much, but it's a built ABA bottom end, a worked JH head. fuel system is completely stock. 








an old pic. of my setup, almost installed.


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## Southcross (Jul 2, 2004)

*FV-QR*

check your air meter plate... it may be binding/sticking. The act of driving it may "free up" the movement of the plate


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## deer_eggs (Oct 4, 2006)

*Re: FV-QR (Southcross)*


_Quote, originally posted by *Southcross* »_check your air meter plate... it may be binding/sticking. The act of driving it may "free up" the movement of the plate

I should've thought of that. I'll look at that tonight while changing the filter, and report back with what I find out. Thanks!


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## Southcross (Jul 2, 2004)

*FV-QR*

also common for them to get coated in engine PCV blowby and becoming physically "sticky"... about twice a year I spray mine down with carb cleaner and wipe it down


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## deer_eggs (Oct 4, 2006)

*Re: FV-QR (Southcross)*

Well, it did this a total of 3 times, and hasn't acted up at all since then... once on a cold start, and twice on a hot start. I did change the fuel filter, and cleaned the airflow plate. The plate was pretty clean, but I sprayed & wiped it down, just to make sure. At this point, I'm wondering if it was just a fuel filter... Thanks again!


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## ABA Scirocco (May 30, 2001)

*Re: FV-QR (deer_eggs)*

I had something somewhat similar happen to me once, I noticed that when the engine was running poorly, I could not hear the frequency valve buzzing. The ecu and frequency valve would cut out intermittently making the engine run way too lean. Eventually, I traced the problem to a faulty ground connection for the ecu. On my car the ground for the ecu attaches to the engine at the cold start valve, I cleaned that connection and everything went back to normal. If your car starts acting up again, that might be something to look into.


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## deer_eggs (Oct 4, 2006)

*Re: FV-QR (ABA Scirocco)*

Ok, that's definitely something else to take a look at. So far, it hasn't acted up since this past Friday, and about 300 miles. We'll see what happens.


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## Southcross (Jul 2, 2004)

*FV-QR*

yes, good point! if the Frequency valve isn't operating correctly that can lead to many issues:
(with Correct Mixture, Good Working O2 sensor, and Correctly powered ECU and Frequency Valve... )
The FV should be operating at 50% (half on, half off), essentially its switching on and off, and should do so fast enough that you can't audibly tell the difference between on or off. If you can hear the valve turn off... thats bad. Either an electrical (first guess as the grounds are typically on the Head and often break/corrode), or possibly a mixture problem (have you ever tweaked it in the past?), or even an O2 sensor failure (leads me to believe its not the case with a Cold engine).


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## ABA Scirocco (May 30, 2001)

*Re: FV-QR (deer_eggs)*


_Quote, originally posted by *deer_eggs* »_ So far, it hasn't acted up since this past Friday, and about 300 miles. We'll see what happens.









Maybe you've already solved the problem, good luck.


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## deer_eggs (Oct 4, 2006)

*Re: FV-QR (ABA Scirocco)*


_Quote, originally posted by *Southcross* »_ Either an electrical (first guess as the grounds are typically on the Head and often break/corrode), or possibly a mixture problem (have you ever tweaked it in the past?), or even an O2 sensor failure (leads me to believe its not the case with a Cold engine).

I have tweaked it in the past, but nothing recently. The problem (atleast for me) happened hot, or cold. I did unplug the o2 sensor, with absolutely no change. I was told about checking the grounds at the cold-start injector, and if it acts up again, this will be the next place that I look.









_Quote, originally posted by *ABA Scirocco* »_
Maybe you've already solved the problem, good luck.

It sure seems like it, I just wish I knew exactly what caused it to begin with... I can only guess that it was the fuel filter, at this point. I've driven it every day since friday, and it has not missed a beat. Thanks again for all of your help!


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## kamzcab86 (Feb 14, 2002)

*Re: FV-QR (deer_eggs)*


_Quote, originally posted by *deer_eggs* »_ I just wish I knew exactly what caused it to begin with... I can only guess that it was the fuel filter, at this point. I've driven it every day since friday, and it has not missed a beat. 

Have you driven it in the rain since Friday? Sounds to me like something electrical got water-logged when you drove it in that downpour; it dried out a tad over night, and the heat from driving it evaporated what remained.


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## deer_eggs (Oct 4, 2006)

*Re: FV-QR (kamzcab86)*


_Quote, originally posted by *kamzcab86* »_
Have you driven it in the rain since Friday? 

No, it's been dry around here for a change... but it is supposed to rain a bit today. I normally don't like to drive my car in the rain (you know how the whole convertible thing goes







) but I'm doing an experiment to see if the symptoms return. It's supposed to rain again this weekend, so we'll see what happens.


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## Southcross (Jul 2, 2004)

*FV-QR*

there isn't a lot of electronics in a Mk1 to be affected by rain/moisture.... not like a OBD I/II car with MAF sensors, Crank position sensors, etc that freak out with any moisture entry. About the only thing that "freaks" when it gets moisture in it is the ignition distributor... or... you have some seriously bad wiring (i.e. broken wiring insulation, which is possible too







)


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## rebel_eye (Mar 29, 2001)

*Re: FV-QR (Southcross)*

I think this is a fuel distributor issue.
Put a jumper on the fuel pump relay terminal and pull the plunger up with magnet. ( take the fuel dist boot off ) 
Observe and note the spray pattern of the injectors.
Put some new orings on while you are at it !


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## deer_eggs (Oct 4, 2006)

*Re: FV-QR (rebel_eye)*

So far, it's been problem-free again!
The o-rings have only about 35,000 miles on them since they were last replaced, but I'm going to get another set to replace them, probably within the next few months.
I did pull 1 injector (couldn't find my injector removal tool, so couldn't really pull the others too easily) and tested the spray - nice cone shape, & no drips. I checked them all about 30,000 miles ago, and all checked ok.


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## stick90 (Feb 28, 2008)

*Re: FV-QR (deer_eggs)*



deer_eggs said:


> Put a jumper on the fuel pump relay terminalQUOTE]
> Where exactly is that? I want to check my spray pattern but am not sure where I'm supposed to hook a jumper wire up


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## ABA Scirocco (May 30, 2001)

*Re: FV-QR (stick90)*

Here's a picture of type of fuel pump relay used in your car, note the terminal numbers, your jumper should connect terminal 87 to terminal 30.


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## teknikALLEN (Jul 14, 2010)

How is this project going these days?


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## ny_fam (Apr 3, 2004)

Fuel pump check valve - replacing them makes a world of difference, starting and in the power department. Not sure if you have one on your model. 
Cheers 
ny_fam


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## Holden McNeil (Jul 26, 2004)

Stupid question but did you remove the Digital Idle Stabilizer yet? If not, do it as it's one less headache to worry about... :beer:


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