I'm still having issues with my TPS. I replaced it with two aftermarket ones (one from Autozone and thne one from ACDelco that was the same PN). And neither one would read less than .75V no matter the position of the blade on my NW 102 TB.

So I went back to stock, and I can't get the car to idle anymore. It reads 2% no matter what I set the voltage to (.63V was were it was set when I put it together - and I've set it from .61 to .67) and it idles really low - like 650RPM even though it's set for 900. I figure it wasn't getting enough airflow. But it's also throwing code 123 with the stock GM sensor.

What's the issue? Is it wiring? Is there something in the tune I need to adjust because it's reading 2% at an acceptable voltage? Is it the TPS sensor?

Car is pretty undrivable. The whole issue popped up in August and I've more or less parked it as I've traveled for work. But now I wanted to get it back on the road and this is pissing me off. It was high idling then so I bought the new TPS sensors and played with the TB, not knowing if the NW was actually moving of me or if the TPS was going out. But the new ones won't read low enough...

 

Throws it with the new TPS as well. But that one won't ever read less than .75V... so even if I close the blade all the way, it reads that. So I lose resolution for throttle position. I set it with the old TPS and put the new one on... but it reads 1-2% no matter what.

I do the TPS relearn each time I make an adjustment or swap TPS.

 

Have you tried / can you elongate the TPS mounting
holes to allow more rotation toward a lower voltage
output?

Might check your 5V (and TPS-local ground) voltages
against a PCM ground at the PCM connectors, on the
off chance this is some sort of wiring or bent-reference
type deal?

 

P0103 is a Maf Hz high code.

Russ Kemp

 

**** it's 123. Not 103. Thanks, Russ.

Which is a TPS.

Jimmy, I have thought about that but didn't have that problem with stock. Closed it read around .4V. What would change now?

 

I do have the MAF tune enabled. I can swap back over to SD and see. But the fact is, it's throwing P0123 with either sensor and seeing 2%...

 

Checked voltage at TPS... 5.94V. So that's why it's going high. If it were lower, I'd think I have a short somewhere. But higher voltage is weird. What's the range? Thought it was supposed to be right around 5V?

 

Yes, the PCM "5V" outputs should be 5.0V and the ratio
error seems roughly consistent with your problem (ought
to see 0.6V at rest, add 20% and you're over the fault
threshold).

Voltage regulators do fail. Some also do poorly at sinking
current and there could be some other actor pushing
the 5V reference upward through some attached
component. Might do a little debug, like snip the wire
near the PCM connector and remeasure - if it's back
in range then the problem is outside the PCM, if it
stays at 5.9V then call the PCM bad. Don't know
whether the 5V references are from easily reworkable
components or not, but could be this is salvageable
(individual regulator ICs are usually cheap and not
hard to R&R).

 

Another "patch" occurs to me, which is to supply the
TPS separately, like use a 7805 regulator from IGN to
power it. And maybe whatever else is hanging off that
5V feed (like, if MAP sensor was 20% off that would
be a tuning mess too).

 

I need to get a schematic and look and see what else is hanging off. I'll check the MAP too. What's the voltage reference on it?