Ok, I figured out one of my TPS issues but now I have a new one.

The previous problem: I have some slop between the hard stop arm and the blade shaft on my BBK throttle body. My PCM sets 0% throttle at some initial voltage of say .59 volts. If the throttle is shut hard enough, the voltage will drop to .56, because of the slop, and the PCM will reset that value to be 0% throttle. A soft closing thereafter will give me the usual .59 volts which is now 1.2% throttle to the PCM. This gives me a fast idle. I have to fix the slop. Ok, now for my new problem...

I can only get a max of 99.6% throttle position. I know it might not mean much but what is the deal?! Even if I take the tps off the throttle body and turn it by hand, I can get the volts to at least 5 volts but the PCM only reads up to 99.6%. Basically, as the tps volts go up, the throttle % goes up until 99.6% and then the volts continue to go up but without any change in the throttle %. Eventually, (with it in my hand) I go over the 4.90 volt threshold and the throttle reading drops to 4.5%. I tried a new TPS and that did not make any difference. Does anyone have any ideas as to why I can not go over 99.6%?

see http://web.camaross.com/forums/showthread.php?t=460427 for history.

 

I thought the TPS needed to show .6-.9V when it was closed. Not getting 100% for WOT is no biggie as long as the blades are opening all of the way. The computer is set to recognize WOT way before that. Is everything moving freely? I don't see why it would keep increasing in voltage when you let off of the throttle.

 

The TPS voltage has to be between 0.20-0.90V in order for the PCM to baseline 0% TPP.

 

The voltage does not increase when I let off the throttle. The throttle% reading dropped during my "tps in hand" test because I exceeded the 4.90volt limit. This confuses the computer so it just sets the throttle% to 4.5%. I was turning the rotating part of the tps with a big screw driver. The voltage was increasing as I continued to rotate the tps but the pcm maxed the throttle% at 99.6%
At wot, above some rpm that I forget, I am maxing out my flow meter and the map sensor. Maybe the difference in fuel delivery is not enough to worry about but I would rather the pcm read all the way to 100%. I also want to make sure this is not a sign of impending pcm problems.

 

I understand what you're saying now. So, basically you're saying that the tb is over rotating the tps? How far are the tb blades open when the tps reaches 4.5V? You have all the way up to .9V at 0% TPS to play with, so maybe you need to slot the TPS and turn it. Maybe that would take care of your over-rotation. If I have this all wrong, don't hesitate to tell me.
There should be no difference at 99.7% and 100%, as long as the tb blades are opened all of the way.

 

Ok. The over rotation was just part of a test I did. Forget about that all together.

Here are two example tables. The first table is approx what I should see and the other is approx what I do see (from memory).

volts=%throttle
0.59v=0%
1.59v=25%
2.59v=50%
3.59v=75%
4.57v=99.6%
4.59v=100%

0.59v=0%
1.59v=25%
2.59v=50%
3.59v=75%
4.57v=99.6%
4.59v=99.6%

 

Just being **** about it. I see. I'm like that with certain things. Now that I understand, I can't offer any help , except to say that it won't hurt performance at all.

 

You got it... I can't stand things that do not work like they should. Of course putting all the work, time and money into these projects that we do, I think we deserve to be be ****. That being said, I'll let this issue go.

 

There's no magic 4.5V limit.... the PCM will accept TPS voltage as high as 4.90V before it sets a code.

What are you using to read the TP%? I've seen several data logs that max out at 99% rather than 100%. It may be a limitation of the scanner.

 

I'm using Ease Diagnostics www.obd2.com. I've had the program for a few years (1999). At one time it would go to 100%. You're right, I meant to say 4.9 volts in my previous posts, not 4.5 volts.