warren (05/18/82)
I have a 79 rabbit that has had idle speed problems from time to time. The problem comes in two forms: 1) Idle is unstable. If you start above a certain RPM, the idle speed increases until it gets excessivel. (I don't have a tach, so I don't know how high it goes, but it's high enough to be loud, but not higher than it goes during normal driving.) 2) Idle speed warbles. The idle varies cyclically, going up and down. In the extreme form, the car stalls on the low part of the cycle. These problems are temperature dependent. The higher the outside temperature, the worse the effect. This has always happened to me after lots of miles without service, and near a time when I was going to bring the car in for something anyway, so I have just taken it to vw, and they fix it promptly. It would seem like some sort of negative feedback system where the gain gets out of whack. Setting back the timing helps a little, but you can't stop it that way without going beyond the normal timing setting. It can't be very tough to fix, since in one case the fix was applied very quickly and for no apparent charge. The service manual doesn't mention this one, but it appears to be very common, as I know several people here who have had it from time to time. I would be very interested to know what is going on if anyone has any insights. My car has 55K miles, and relatively few problems. (I had the oil burning fix done ad 45K, and so far everything is fine.) Warren Montgomery ihnss!warren