I recently removed & cleaned my TB. I reinstalled everything and reset my TPS voltage to .54. Idles as well as it ever has; after I calibrated the idle, I then checked to make sure the run up to WOT was a smooth and steady increase, which it was. My issue is at WOT, it only registered 3.25 volts. I've read that it should be 4.00 or so. Is this indicative of a malfunctioning TPS or should I just leave it alone?

 

On LS1's there is a free mod called the bump stop mod. I did this to my 99 T/A. What it does is allow the TB blades to open up more so the PCM reads max volt for WOT.

Im sure there is something like this for our L98 TB, I think we have a bump stop we can adjust manually. Try adjusting this.

 

Hopefully this post will help someone. The symptom in the original post was one of a couple problems I have had trying to get the idle speed to actually idle. From the time I got the car back with the 355 (May '05), neither, I, nor my dad, the guy who put the engine in, or another mechanic could figure out why the idle would bounce around and/or hang above 1200, and looking back at the things I fixed, I think we should all hang our heads in shame. At first I set the timing to between 6-8 degrees; it was left at zero from the engine install..DOH! I replaced the IAC. I set minimum air, twice (although the 1st time was done incorrectly). I set the TPS, twice. Checked for vac leaks. Cleaned the TB. Checked for a hung throttle cable. So finally, I set out on the road with my scanner (this was the 10th time I did this kind of diagnostics). What was weird was it would idle prefectly at times, them go schizo on me out of the blue. Usually it would behave after I had turned the car off and the started it up again. I noticed on one idle hang that the TPS voltage was 1.1 Yikes. Couple this with the 3.25 WOT and I finally put 2 and 2 together to realize my TPS was bad.

Well, some folks would say that was the 1st thing I could have replaced, but I have read OVER AND OVER on this very site how it's a bad idea to just go replacing parts and sensors. By god, I checked everything I could find and the sensor was the LAST thing I replaced. If the TPS was not the answer, I was out of answers and was just gonna have to give in and take it to a pro.

I'm sure some of the more experienced mechanics on TGO may be laughing at me, but I KNOW there are 100 other guys with the same problem. I'm really, really happy to be rid of this problem as it has dogged me for 11 months. I am glad to have gone thru all the research and whatnot, as all of my "tests" and "fixes" were gleaned from the oft-suggested "Search Function" of this forum. I sure hope life will not be this hard when I replace the intake manifold!! haha (only partially laughing...)

Eric