Surging idle
 

Today I had a weird idle situation, third time this happened. Once soon after buying the car I first encountered this symptom. I would start the car and it would start, then all of a sudden the engine would start revving to over 2k RPM by itself. Then suddenly drop back to idle around 900 and then accelerate itself again. If I added my own throttle up to around 3k then let go, everything was back to normal. I assumed it was because of bad maintenance. Now after all my new parts and upgrades it happened again yesterday, and then again this morning. Only correlation I have is that I have been parking outside temporarily instead of in the garage.

Have you cleaned the TPS. I had some issues with mine a while back so I took the TPS off and cleaned all the gunk off of it. There is a little passage that allows air through when the valve is always closed, get in there really good and clean it out. There is also a good deal of vacuum included in monitoring the idle in these cars. If your lines are the original ones you may want to put on fresh ones as well as some new T joints. A cheap job and you may find some lines that are either disconnected or broken.

If you have not replaced it a fresh air filter will do nothing but help as well.

There are also vacuum valves involved in the injection system, I dont know much about them but they could also be an issue. I would start with the lines and TPS and work from there.


Regards
Dave

I guess I'll need to check the TPS. I have new plugs wires cap rotor. All new vacuum lines are a month or two old from LR. The fuel filter was changed last year, less than maybe 7 or 8 thousand miles ago. I have a K&N air and oil filter in now with only maybe a hundred miles on it.

I would check the TPS as others have stated.If that checks out you might have a issue with your ICV(Idle Control Valve)I have seen vw and audi cars do this due to a faulty valve.I believe there is a procedure on clarks garage on how to check if the valve is good or not with a DVOM.Those are the 2 things i would check first.

Does anybody have a diagram of those systems?