Hey guys this has been an on going struggle. These are the major details: When I start the car it starts fine but the engine revs from 2.5k to 4k over and over agian...it won't go any lower than 2.5k even if I let it run for 5 minutes. If I give it more gas and just hold it, it will do something like rev from 3.5k through 5k over and over again. Things that have changed since the last time the car was running correctly are: Large single turbo, catback went from 2.5 to 3 inches, larger intercooler, crane ignition amp, and changed the primaries to 850ccs. The car before this run of mods had all the basic bolt-ons with BNR stage 2s running parallel. I have not touched the fuel maps. The only change with the power fc was that I plugged in the 850cc primaries. The secondary butterflies have also been eliminated and I no longer run coolant to the uim. I have done the wire mod to fool the thermoplunger. Anyone have any bright ideas? I would be thankful for any suggestions as I am out of ideas as to what could be wrong. Could this possibly be just the fuel maps? I wouldn't think that they cold cause the idle to be so super high like that.

 

Check for any vacuum leaks after the throttle body - that's a primary culprit for high idle. Might also want to pull the throttle body off and verify that the throttle plates are CLOSED and there's nothing keeping them open. Use a light behind the throttle plates and make sure you don't see any light around the throttle plates.

It's likely something easy. The only way for the car to have a high idle like that is extra air getting in, either through open throttle plates or through a vacuum leak.

Dale

 

I had the throttle body off about 2 days ago to do the thing with the thermoplunger. I noticed the bottom throttle plate would allow air by even at rest. I just assumed that was normal to allow the car to idle. The opening was about 2-3mm. Is that normal?

 

anyone?

 

You can also check your throttle sensor... it could also give the same problems as you describe if its not functioning properly

 

What is this thermoplunger thing? Does this have to be done when doing the throttle bypass mod? This might be MY problem. What are the symptoms of not doing it?

Thanks,

Andrew

 

The throttle plates should all be closed at rest. If they're not, work and study the throttle linkage to find out what's the problem.

The "thermoplunger thing" is also called the thermowax. It's a piston that pushes a cam that closes the throttle plates. The water going through the throttle body warms a pellet of wax that's under the piston and makes it expand, kicking the cam down. This is why you have a 1500 RPM cold idle that slowly comes down as the car warms up. If you remove the coolant lines from the throttle body, you have to disable the cam. Best way to do it is to totally remove the thermowax assembly, the spring loaded cam, etc. It's a bit tricky, not too bad. I've messed with TONS of throttle bodies .

Dale