I tried starting a new rebuild recently and when it finally turned over and started up, the RPMS went to 4k and stayed there for the entire time the car was on. Granted I only left it on for about 5 minutes or less when I realized it was doing this. I've had the car start about 5-6 times now and everytime, it does this. I've checked the throttle cable and I've checked timing. Both the throttle cable and timing are ok. Throttle cable is in place and timing is set to TDC.

This has me thinking that there may be a vacuum leak somewhere? Am I correct in assuming this?

 

Maybe the throttle plates are stuck open. I thought a vac leak would cause it to idle rough or not at all. I'm not sure though.

 

How would the throttle plates be stuck open exactly? I never touched the throttle, minus the cable, in which I loosened when mentioned to me before?

 

I don't really know. Just a guess. sorry

Some other things you might want to check (just some random guesses): AWS, BAC, MAF, TPS.

Hopefully someone who actually knows what they are talking about will post.

 

regardless if you "touched it" or not... the throttle body would be one of the first things you should look at... verify that the plates are closing and that the throttle moves freely... is the throttle cable adjusted correctly?

did you reuse any old manifold gaskets.... fuel injector o-rings?

do you still have the rats nest?

have you plugged all vacuum ports that are not being used?

if its a vacuum leak, use a can of brake clean with the little red tube and spray a little here and there... if you spray it in a paticular area and the idle changes that is your air leak

 

It can't be a vacuum leak, a leak that big would cause the ECU to shut the car off because of the large amount of unmetered air entering the engine. Vacuum leaks usually only raise idle a couple hundred RPM.

Sounds like the idle screws need adjustment to me. Two of them, one on top and one on bottom with the locknut. Or the BAC could be stuck open...remove the hose going to it and plug it to see if it goes away. MAFs don't go bad and TPS can be ruled out by disconnecting it and seeing if it goes away.

 

I doubt it's that. If those were missing, the car wouldn't idle or would idle roughly. (ask me how I know )

 

Says your car is a TII. Go to home depot and buy a cap coupler. Size is 1 1/2. It will go over the intercooler opening, after the charge pipe. Hook it up and run compressed air through the engine with the throttle body jack all the way open. You should hear if you have a leak.

(If course you have something to feed the air into the engine (Air compressor with regulator) Also you need a valve so the air can enter the engine.)

 

don't forget to check your cruise control cable..I put mine back on incorrectly and it raised my RPM's when I went to start the car..

 

idle screw on the throttle body. use a flate head and loossen it!

 

The throttle cable was adjusted and even left somewhat "loose" to see if it was the culprit. To no avail, no change.

I used ALL brand new gaskets when I rebuild the engine, including the o-rings, when they were tested and cleaned.

The car is basically stock, as far as emissions goes.

All unused vacuum nipples were capped off.

 

I removed the cruise control unit. The actual mechanism. Would that subject the idle to rise as much as it did?

 

If the CC cable was improperly adjusted or not installed correctly yes, it could throw the idle way off.
All you need to do is pull the cable from it's bracket on the thermowax and see if the idle goes back down.

Other than the cable, the CC has no way to affect the idle...or anything else really.

 

The cruise control was completely removed. The only cable going to the throttle body is the throttle cable.

 

re-using old dried up crusty o-rings will leak...

 

yeah, you're right. I guess I didn't think of that.

 

All seals for my injectors were replaced and none were reused on the engine build.

 

Did anyone miss the obvious? It could easily be the thermo wax sticking out and not moving back in. This would be the AWS or Accelerated Warmup Start (err something like that) procedure which zooms the RPM's to 3000 or 4000 RPMS and then goes down till the engine is warm. But this could easily be stuck in place if the thermo wax is not moving it would cause a similar situation.

 

Well this may sound kind of stupid but when I took my engine out to clean It I had a similar issue. To fix that I had to adjust the Idle speed on the throtle body and TPS.
How about trying that.