Question/ Problem with TPI...

[gn85]

Hey y'all,

I have a Monte Carlo with 305 TPI. Just did a motor rebuild and the car was running fine. Before the rebuilt (and shortly after) the car ran just fine. Now the car idles poorly, stalls, runs pig rich, etc.

Just recently it started running bad and I didn't have a scan too. So, I picked up a scan tool and when I plugged it in, I got some WACKY numbers and I'm wondering if that could be an indicator that the ECM has gone south.

Example of wacky:

Prom ID = 0
CTS = 124.7 (car's cold)
TPS = Starts off at 4.7 and drops incrementally to zero then starts over. Does not react to pressing gas pedal.
Speed = Same thing. Starts at 155 and drops to zero (car sitting still)
Integrator = 0
Block learn = 0

I could go on. I thought maybe it was the scan tool so I took it out and hooked it up to the Buick. Worked just fine.

Anybody have any ideas?

 

[bruce]

Originally posted by gn85
Anybody have any ideas?

Double check all the grounds.
Make sure a wire wasn't pinched under say a valve cover.

Off hand it sounds like a 5v reference wire is pinched to ground.

Use an ohmeter as much as you can, leaving it on too long with a short on say the 5v refence will take out the ecm.

 

[gn85]

Re: Re: Question/ Problem with TPI...

Originally posted by bruce


Off hand it sounds like a 5v reference wire is pinched to ground.

Thanks for the info.. I had already double checked the grounds because that was the first thing I thought of.

As for the 5V ref, I was thinking the same thing, checked and did not get any cont. to ground. I unplugged the ECM and checked the cont. from the plug to the TPS and MAT and was getting good cont. but nothing to ground.

I'll check it one more time to make sure. Since the readings are so odd, I have a feeling that its a wiring or ECM problem.

One question, although I don't think it's related to this problem. On the MAF I notice that there is a ground and an 'analog ground'. How is that ground established?

Thanks for the response.

 

[bruce]

305, TPI, with MAF?.
That's probably a 1227165 ecm, they're known to do goofy things when the ecm dies. I was figurin you had the MAP system.

I'd still say go wire by wire thur the ecm harness, and check everything, before plugging a new ecm in.

As far as 165s go, might as well just go with a junkyard replacement. While there is an updated one, 16197128 it's not too likely you'd get one as a rebuild, thou.