Working on my brother's 68 camaro with a 01 camaro ECU and harness (05 Caddy ESV block and 243 heads)
Yesterday we cleaned up the battery ground point from the battery to the body (relocated battery to trunk) At the same time, I also installed a set of truck coils.
Since then the car doesnt run correctly as it did before, it sorta holds the idle or hunts for it, just like if the TPS sensor was bad. Pulled the codes and have a P0122 for the TPS. Checking the sensor, it all appears to be working correctly, getting the 5v ref, good ground, and good sweeping voltage when throttle is opened. But the p0122 will not clear.
Actually .45-.55 volts. The PCM tries to enter a different table if the voltage is not in this range.
If that is all you did, try the following.
You may need to do a idle relearn procedure. Sometimes when the battery is disconnected for an extended period of time, the PCM needs to relearn the TPS and IAC positions.
Turn the key off, engine off.
Unplug the TPS connector and IAC.
Turn the key on, engine off.
This will set the TPS and IAC codes.
Turn key off, reconnect TPS and IAC.
Start engine. The idle may hunt for a few minutes until it knows the air flow requirements and then stabilizes.
__________________ 1969 Firebird: 11.67@114 7.55@97.93 1/8 1.70 60 ft. and 11.70@116 1.76 60 ft. 6.0 LQ4, L92 heads milled 10.8:1, L76 intake, 90mm Holley TB, 85mm MAF, FIC Custom injectors, custom Comp cam (222/238 duration, 581/605 lift, 114+4) Hooker LT, PYPES dual exhaust with an X pipe, 4L60e with all of the good parts inside, TCI 3500 Super Street Fighter TC, 12 bolt with 3.73 gears. HP Tuner tuned by me
also, when the scanner is connected to the computer, and the car is running.. The Ignition Voltage reading is at 13.8 at idle but when you raise the RPM's up it drops down, the lowest reading was 6.5v. My GTO doesnt do this it stays at 13.8 thru the entire RPM range, what could cause this?
Sounds like ground issues.
Where is the battery ground connected? I have a first gen Firebird, battery in trunk also.
Big heavy cables or braided ground straps
Ground from the engine to the subframe.
Ground from the subframe to the body.
Plus the normal engine grounds on the drivers rear of cylinder head.
Drivers front lower block.
Front of passenger side cylinder head.
__________________ 1969 Firebird: 11.67@114 7.55@97.93 1/8 1.70 60 ft. and 11.70@116 1.76 60 ft. 6.0 LQ4, L92 heads milled 10.8:1, L76 intake, 90mm Holley TB, 85mm MAF, FIC Custom injectors, custom Comp cam (222/238 duration, 581/605 lift, 114+4) Hooker LT, PYPES dual exhaust with an X pipe, 4L60e with all of the good parts inside, TCI 3500 Super Street Fighter TC, 12 bolt with 3.73 gears. HP Tuner tuned by me
P0122 code 
