# CIS-E idle adjustment problems



## Flyingsheep (Apr 24, 2008)

My idle has never been right since I bought this car and I need help. I've had a volkswagen guru reset the idle for me and I've tried resetting it myself without any luck. What it does isn't really serious but it's obnoxious. After the engine is in operating temp it idles between 1100 RPM and 1500 RPM. After driving for a while it "sticks" at about 1500 and refuses to go any lower. On cold starts the idle stays around 1000 RPM. Today I read up on how to adjust your idle properly on CIS-E so I went out to do it myself, thinking that maybe the guy who helped me do it months ago had adjusted it too high. I warmed it up, waited for the radiator fan turn on at least once, and revved it up between 3k-4k RPM. It dropped to 1400 RPM and slowly started going down, which I know is normal. It stopped dropping at 1100 RPM and just stayed there. So I adjusted the idle screw carefully until it sustained at 1000 RPM. I didn't drop it to 900 because there's a rattle that comes from the valve cover it seems like when it idles that low. I revved it up to 3k-4k RPM again and let it drop, and it STILL stuck at 1100 RPM! I repeated this procedure over and over and each time the idle would drop down to 1100 RPM and sit there. When I adjusted the idle before I would rev it up it would drop down just fine. It's always after I rev it that it seems to "reset" to 1100 RPM again. The bypass valve was also becoming more and more screwed in...







apparently not affecting the idle. I decided to stop because obviously something isn't right and I was only closing the bypass valve more and more.
So, any ideas? Vacuum leak? How do I check for those?


_Modified by Flyingsheep at 3:13 PM 10-15-2008_


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## teutoned (Jul 29, 2008)

*Re: CIS-E idle adjustment problems (Flyingsheep)*

check for vacuum leaks using brake cleaner or starting fluid. spray on or around all vacuum lines and boots listening for any change in idle.


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## yeayeayea (May 29, 2005)

*FV-QR*

sounds dangerous. 
If theyre old, it cant hurt to just replace them. it cost like 5 dollars in vacuum line to replace all the lines.
could also be the ignition timing, i have been playing around with mine and it definitely adjusts the idle.


_Modified by yeayeayea at 8:42 PM 10-18-2008_


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## Fjogh (Jun 22, 2007)

*Re: FV-QR (yeayeayea)*

One small O-ring to replace is the one where the additional air goes into the head for air shrouding. Replacing this fixed my problem


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## piledriver (Jul 29, 2008)

*Re: CIS-E idle adjustment problems (teutoned)*

Vacuum leak, definitely.
Brake cleaner is non-flammable and works great, but make certain to only use it in a very well ventilated area.
(may use propane propellant, but the brake cleaner itself puts out fires)
If any gets sucked in, it out the fire out, rpms drop.
What comes out the tailpipe won't do your lungs any favors either.
Air shrouded injectors would be a definite place to look, as would the related plastic inserts/orings, as well as the injector orings themselves.
Do yourself a favor and buy all new insert etc, and pehaps 1 spare set, as well as the green Bosch injector orings.
Autohausarizona is quite reasonable.
They also had the Mercedes brass injectors for $20 ea... The air shroud tips will swap over, just make sure to press them all on to the same depth (and NOT fully flush)


_Modified by piledriver at 5:28 PM 10-19-2008_


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## Flyingsheep (Apr 24, 2008)

Where can I get new vacuum lines?


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## piledriver (Jul 29, 2008)

*Re: (Flyingsheep)*

The Stealership can set you up in an emergency, but any Foreign auto parts store will have metric vac line...

If you really know aht you need, Autohausarizona probably has it by the foot.
In a pinch, some of the SAE sizes work, but the good OEM style German braid covered line lasts a LOT longer than the generic stuff.


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## Bil83GTi (Oct 17, 2008)

*Re: CIS-E idle adjustment problems (teutoned)*


_Quote, originally posted by *teutoned* »_check for vacuum leaks using brake cleaner or starting fluid. spray on or around all vacuum lines and boots listening for any change in idle.

to check for vacuum leaks use a chlorinated brakekleen, don't use non chlorinated or starting fluid they will be the worst way to find out if you have a random arcing plug wire when they flare up in your face! silicone vacuum line will last you the longest usually only come in metric and most parts stores(as long as they have someone competent and product knowledgeable working that day) should be able to get you some, i work for advance auto and got an 8ft roll for $12, silicone stretches easier than rubber so even if you have to get generic standard sized hard lines it will fit, and since it usually comes in different colors the old lines will standout so you don't miss changing any if you are going for all, I can post some part numbers for you if you want it will make it a lot easier to order if you have them


_Modified by Bil83GTi at 3:50 AM 11-1-2008_


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## Jetta2dr (Feb 19, 2001)

*FV-QR*

I dont like silicone vacuum line, I've seen it collapse under vacuum and cause funny problems.
Nonchlorinated brake clean is just as flammable as the other stuff, try it some time.
I'd say check your ignition timing for sure.


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## Flyingsheep (Apr 24, 2008)

I actually was considering it might have something to do with the ignition timing. I can't remember why but I read somewhere something similar and it was the timing, I think. Sorry to sound like a n00b but how do I check it? I've never messed with timing before so I hardly know anything about it.


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## Bil83GTi (Oct 17, 2008)

*Re: FV-QR (Jetta2dr)*

that's why i said to use chlorinated the propellants in the can are flammable but the actual brakeleen isn't as volatile, so it takes a little more than an arcing wire to light it up, trust me I've done some stupid **** with flammable chemicals


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## oldskoolracer (Mar 6, 2009)

So I just wanted to chime in on this being that Im having a very similar issue with mine. (89 gti 16v). The idle surges a little sometimes but not always. This thing has had every little tune up item done I can think of, includin the timing belt. Ive set and checked, double checked and triple checked the timing and got it dead on @ 6*. Ive replaced all the underhood vacuum lines, double checked all the wiring, cleaned, taped and re-loomed anything that looked questionable. I can turn the bypass screw in or out with very little to no difference in idle speed just runs smoother or rougher... My thought is the IAC? Whats the best way to test the IAC values to be sure?


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