Help guys, my FD is idling at 1500 no matter what I do. It's not a vacuum leak and we've tried resetting the tps.

 

did you check the fast idle cam?

 

Here's the deal.

High idle can ONLY be caused by air getting past the throttle body. Period. End of story.

Now, HOW this air gets there is the interesting part. A vacuum leak between the throttle body and the engine will do it. Or, if the throttle body is stuck open for some reason, that will do it as well.

Common culprits -

- Vacuum leak. This is ANY air leak after the throttle body, from a vacuum hose popped off to a bad/leaky gasket. Easiest way to find is using starting fluid - spray around the engine in short bursts with it running. The vacuum leak will suck the fluid in and the engine will rev up/change how it runs.

- Stuck open throttle body. This can be a throttle cable adjusted too tight or a throttle stop someone played with.

- Stuck open fast idle cam. If you removed the water lines that go to the throttle body, the fast idle cam won't kick down and the idle will stay at the higher warm up setting.

Another weird one I've seen before was a stuck ISC. It actually had something jammed in it keeping it open, allowing air to pass through it and bump the idle up.

It's just air getting around the throttle body, you just gotta figure out where that is.

Dale

 

I had a similar high idle after doing a vacuum hose replacement. I tried adjusting the idle air bleed and couldn't get it into spec. Next I checked for leaks and tried all the other trouble shooting things like cable ajustment, etc. Nothing worked. Then I noticed that the throttle plate was not fully closing with the accel cable and fast idel properly adjusted.

There are small hex head set screws that control the throttle stop. By adjusting those, I got the plate to close fully. Once that was done, I used the air bleed adjusment to make the final adjustment. It been dead on ever since.
Hope that helps. Just note that it very difficult to get to those screws with out some disassemble. If I remember correctly, I had to remove the throttle body to get to the one closest to the firewall.

 

It was a lower intake gasket.

 

I had the same problem recently also. Cold starts I would idle at 1500 and after warm up would drop to about 1200-1300.... She idles great now after I removed all the emissions stuff, ISC, and double throttle. Hard as hell to start her up with this cold *** weather though.

 

Need a new gasket?

 

Thanks but I've already got a new one coming.

 

Since you are replacing the LIM gasket, you might want to go to this forum thread and download the attached MS Word document in post #2. It will give you some idea of what is involved in replacing the LIM gasket with the engine in the car.

 

Fixed!! Thanks for the input and advice.

 

How exactly did you figure it out? What method did you use?

 

Trial and error really, the engine was eating the lower intake gasket due to the previous owners lack of experience. But not a big job just tedious.