Every so often, my TPI motor will idle high; and I need to blip the throttle to bring it back down to normal. It will just hang at 1500 RPM's, and when I blip it, it comes down to ~800.

It's mostly stock, with a Holley 52 TB. Nothing is hanging up. Everything moves freely. New IAC motor, which resolved the stalling.

Any ideas?

 

I have a similar problem where the idle is occationally high, although it might not be the same cause. For me the TPS is giving a bad reading causing it to think it is off-idle, so it opens the IAC and raises the RPM. If you have a scanner you can verify if this is happening, or you may also be able to backprobe the TPS and read the voltage under normal and unexpected conditions.

 

that sounds like a binding throttle body, as they wear out they can get stuck and bind against the bores of the throttle body. I just fixed this in my car a month or two ago.

https://www.thirdgen.org/forums/tech...hard-foot.html

 

I believe the TPS is the problem. It happened yesterday, I got out, opened the hood, and the TB was fully closed. I played with the TPS tab, but not opening the throttle, and sure enough I can raise the idle just by playing with the TPS.

I just ordered one from rockauto. $10. I should get it this week.

 

I changed the TPS, did the reset procedure. And now the problem is worse. The intermittent idle is way higher, and it's happening more often. It's a Holley TB, with little miles on it. I'm outta ideas. New TPS, net IAC. Is there anything else that affects idle, that can be blipped down ?

 

Note that a new TPS does not necessarily mean a good TPS. I got a brand new ACDelco TPS, and it had frequent problems of dropping out right out of the box. The best thing to do would be get a scanner and actually see if the TPS is causing the idle to raise.

 

Bad TB... It's binding when hot. Not when cold. I wasted money on a TPS. This is the 2nd bad TB I gotten over the years.

It's not the spring, it snaps back very hard. I think it's the blades inside expanding when hot, and hitting the interior of the TB.

If I come off the throttle lightly, it'll stick. If I lift off hard, the spring will snap it back to closed position.

We'll call this a Holley POS.

 

I had a feeling, your problem was my exact problem.

I've had good luck with a professional products throttle body but aftermarket throttle bodies like holley and BBK have been known to be crap. There's a guy online called Dr. Injectors who rebuilds the stock ones and many people have loved his work. It's worth checking out

 

Many years ago, I had a bad TB from AS&M. They refused to help me, so I put the factory TB back on. Too bad the factory TB is just worn out.

 

Before trashing this expensive TB, I'm going to lightly sand the edges of the blades. It only happens with the engine on, so maybe the vacuum is assisting the blades in sticking open. But nothing else can be binding. It has to be one spot on the blades hitting the interior of the TB.

 

Dr. Injector
1-888-438-1968 PST

He does good work.

 

There was a guy on ebay years ago. EFI something, or another. The guy was a total douch bag. He screwed me out of money.

 

I just pulled the TB off. I literally sanded out every little piece of carbon where the blades could possibly bind. The interior bores are perfectly clean. I sanded the edges of the blades. brake cleaned everything. Now the problem is worse than ever before. It only sticks open under vacuum. Engine off, it snaps back closed every time.

 

What you want to check for is play in the throttle bodies shaft, try wiggling the blades up, down, left, right. There shouldn't be any play at al

 

The problem is the engine vacuum is stronger than the return spring. It will hang open, let's say at 2000 RPM, and if I shut down the engine, the blades will return to closed position. Guess I can add a secondary return spring, or buy a new TB..