Just got done working on the car. Pat (ncider) and Chris (hz900) and Brad were over to help out as well. What we accomplished:

1) Reinstalled cat which looked perfect (no clogged up issues)
2) Replaced the cap and rotor---old cap and rotor looked like it had some corrosion but nothing significant
3) Changed the oil and filter
4) Hooked up the laptop to the FelPro ECM and got a bunch of confusing readings

While the car was not running with the key in the on position several readings on the F.A.S.T. laptop program were not making any sense:

1) On some occasions the TPS (%) reading would fluctuate from 60 to as low as 30 even when the gas pedal was not being stepped on
2) The M.A.T. was also fluctuating anywhere between 115 degrees to 40+degrees. There were even occasions when it read -4.5 degrees. Yes, negative 4.5
3) Something labelled B.P.W. was also fluctuating while the car was not running.

Now, while the car was running the rpm's read correctly, and most of the other parameters appeared to read correctly.

What is going on? The car still runs like crap. It idles fine, then surges, then sputters, then dies at other times. While the car was not running, the highest we could get the TPS to read with the gas pedal mashed to the floor was 95%. It would only go as low as 6 in the beginning and no lower than 16 by the end of the day despite readjusting the TPS.

Could this be a faulty TPS and MAT? Or could the ECM be faulty and reading it wrong?

For more details, see the previous posts:
http://forums.corvetteforum.com/zerothread?id=619457
http://forums.corvetteforum.com/zerothread?id=619771
http://forums.corvetteforum.com/zerothread?id=620966
http://forums.corvetteforum.com/zerothread?id=626378
http://forums.corvetteforum.com/zerothread?id=628055

 

have you done a comp. test yet. still watching you. :thumbs: :lurk:

 

On my '87 the TPS, MAT, CTS all share the same common ground at the S152 junction which goes back to D2 on the ECM.

I had a TPS going from .54 to .30 at idle the other day. When it would go to .30 it would also only go to 2.3 at full throttle instead of the normal 4.6 Thankfully I replaced the sensor and all is now well and it wasn't a problem with the ground outside of the sensor.

 

Although I know there is no way to be sure without running a comp. test on each cylinder I would be willing to bet by the way it was running and the symptoms that his comp. is fine.

I really acted like it might be in limp mode. It is acting alot like my old one did when the MAF went out, but he has no MAF.

Keep in mind guys that he has an aftermarket Felpro ECM so it does no good to ask if he is getting any codes cause we are not sure if the Felpro ECM works that way and will give a Service Engine Soon Light.