88 90 quattro not idling

[asendent101]

The car has the ability to start, but will not idle under its own power. As soon as you take your foot off of the gas, the car dies. It seems like it drives fine, when i can get it to start. I have absolutely no idea what could be wrong with the car. I hope somebody can help me.

[mumutley]

Hi
What size engine?

[mac14]

There should be a little throttle bypass screw, they gunk up pretty easily with oil from the breather system. Also the ISV could be an issue, take it off and clean it out with carb cleaner or the like, then lube it with WD40 or something. The ISV could also be dead, my revs drop dramatically if I unplug it, same if you pull the dipstick. So air leak maybe?

[scotty33]

I would start with looking for vacuum leaks, the 'michelin man hose' would be a good place to start, the crankcase breather is low down under the distributor, this is a really common one too. Pulling the dipstick or removing the oil filler amounts to a vac leak hence affecting running.