Re: rough idle

[Mike Cripps <crippsmp@xxxxxxxxxxxxx>]

Neil -

Had similar problems with my '99 WE. The technical answer was "Throttle 
Body Idle Adaptation Limit Reached".
Basically, the throttle body can't be tweaked any further by the ECU to 
keep the idle steady. With mine, the
idle would be erratic and /or unmaintainable with the A/C engaged after a 
long run on the highway.
VW swapped the throttlebody under warranty the first time, since then I've 
learned that the T-body is simply
dirty/sooty. Pull the intake hose from the t-body and inspect the throat 
with the plate open.  I used
carb/t-body cleaner on a lintless rag to *carefully* clean it up. Some just 
spray the cleaner into the t-body
until it's clean. That can make for one hard start the first time 
afterwards (don't ask...).

While you have it out,  clean the intake hose. Most have found a minimum of 
a oil fim in it, more likely
a small puddle of oil near the crankcase vent tube. You might even find 
your air filter saturated with oil.
Kinda common on the 2.0L.

Once you have it all cleaned up and reassembled, start it and let it idle 
for 2 minutes for the ECU to
reset the idle parameters. Then hit the streets and see if it doesn't 
behave.

Regards,

Mike



On Sunday, August 18, 2002, at 05:54 , Neil Welch wrote:


> I've been having trouble with the idle speed on a 98 GL with about ~75000 
> mi. on it. The engine used to be all over the place after the car was just 
> started, anywhere from ~500-1500 RPM. During driving it was rarely a 
> problem. I thought it was some bad gas so I've used some STP brand and 
> other gas treatments every tank for about a month and a half. The idle is 
> ok at startup now but still persists when turning on the AC. Any ideas?
> I suspect the fuel filter and am wondering if i should replace myself or 
> take it to a shop. Is it a complicated task or a simple half hour job?
> Any advice is appreciated.
> -- Neil
Mike Cripps
mikecripps@bellsouth.net