Some of you may remember my thread a few months back on my 383 LE3 that had issues.

I have finally gotten more time to work on it, and got a few things taken care of, and am still having this problem.

backround info:

The ECM/PCM needs to read somewhere between .23 and .9v on the TPS sensor to read as 0% throttle. At startup if the voltage is in that range, it baselines that as 0% throttle.

Below .23v and it sets a DTC 22 (I think), for too low TPS voltage.
Above .9v and it sets one for too high of voltage.

On my car, the voltage has to be at .03v to read 0% throttle.
Yes that sets a DTC after a few mins of running

This problem exists both with the ignition on/engine off, and ignition on/engine on.

In the process of trying to get this fixed I have:
-----------
swapped the TPS with another, no change.

swapped PCM's, no change.

removed the PCMForless chip, no change.

checked and verified the 3 wires at the TPS are good.
5v, ground, and sense all work fine.

I know I have a ground issue from another problem, so I put in
0 gauge wire to replace the engine/chassis and battery/alternator grounds, along with the alternator+/battery+. No change




Does anyone have an idea what can be causing this?

 

What is the question?????????

Is the question "how do you get from .03 to between .23 and .9 volts?????

You have to cut slots in the TPS mounting holes so you can rotate the TPS to the proper position to get the desired voltage.

 

I think his question is why does the throttle position percent (TPP) not show 0% unless he adjusts the TPS volts down to 0.03V, setting the code for low voltage. If he sets it any higher than 0.03V, the PCM reports the TPP as a non-0 number, like 4% or 6%, when the throttle is closed.

 

Yes, Injuneer is right.
I have slotted the TPS and adjusted it all over from.03 to .9.

any idea's?

 

I think you're clairvoyant

In regard to the problem. It would have to be a programming issue.

 

Not clairvoyant.... I just remember he posted a rather extensive thread on this problem a couple months ago. Probably would have been a good idea for him to at least provide a link to the earlier thread.

The problem is beyond anything I have ever seen before.

 

Thats what I had thought, but I replaced the PCM with no change, and removed the PCMForless tuned chip with no change.

One thought:
Is it possible to remove the DTC 22 so I could set the TPS to .03v and just say screw it? Drive around like that? Right now after it sets the code when I have the TPS that low it I am not sure what exactly it does, but the car gets angry and starts having a hard time running......

Not sure if that possible to remove that code completely, but its the only idea I have right now.

 

When a 22 sets, it will not allow the TCC to set in the tranny. Harsh shifting will occur at set rpms and you will no longer have fourth gear when hot.


If you tried 2 different PCMs and 2 different TPS, then you missed something in the wiring.

According to the manual

The TP sensor has an auto zeroing feature. If the voltage is within 0.3 to 0.9 volts, the PCM will use that value as closed throttle.

I suggest a thorough investigation of the TPS circuit as described in the shop manual. With a scanner and KOEO, check the TPS signal to see that it is below 0.2 volts.

Then disconnect the TPS and jump the grey to the blue wire. The reading should then be over 4 volts.

Using a test light connected to the + terminal of the battery, touch the other end to the blue wire with the TPS disconnected but with KOEO and the scanner connected. The reading should be over 4 volts again.

Then let us know what you found.

 

what is a KOEO?

 

Key On Engine Off

 

oh duh.
okay I'll run through those again.

 

Just checked those.
Everything did as it should.

sigh.

Is it possible to delete the DTC 22?

 

I had a problem with my throttle body linkage having play in the mechanism which caused my idle to move up and down depending on its position. The only relavance I see in that is that no matter what position it was in, the pcm would make that voltage 0% throttle upon startup, ranging from .70 to .80. If you set your voltage at .5 KOEO then turn off and restart pcm should set that to 0% right?

 

Yes. Mine isn't doing that.

 

well that is the question for sure. Why is your system not resetting to 0 upon startup.

It is odd, that you have....

1. Swapped PCM
2.Swapped TPS sensors
3. checked all wiring running to TPS

and still not put your finger on the problem.

Is there anything in the wiring schematic that would do something like this as a side effect? What I mean is.... can another underlying problem cause this via wiring?