Just made an engine swap in a 86 TPI IROC to a pretty hot 355 in place of the 305. Any idea why it would crank and idle somewhat OK (a little rich),, then all of a sudden start really loading up right after the fan kicks on,,, and stall out? The only code shown was 44 (lean),, but it was running so rich at the pipes it would make your eyes water. While it was idling rich to begin with,,, it did not start really loading up until it reached operating temp. The only way I could get it to crank back up (185 degrees) was to give it some throttle,, someone suggested the IAC on a similar situation (but they had no codes),,, and rarely do folks come back to the post and say,,, yep that was the problem,, ya know? Still can't figure out why it would code 44 and run rich. Unplugging the MAF made no difference,,, still running rich and coding 44??? Any ideas?

 

Hmmmm, ya ever think that maybe the O2 sensor is bad or there is a poor connection making the computer think it is lean, so the ECM dumps fuel into the engine, but because the sensor is bad, it never reads rich and you get super rich exhaust, but a lean code. It happens alot.

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"I used to have a handle on life, but then I used it as a plunger and broke it" -The Wave

ASE Master Tech + L1
Savannah, GA
'87 Trans Am-K&N,Cold air induction, SSM SFC, Boxed LCAs, 8mm Accel wires, Flowmaster, 16" GTA rims.
'97 Bonneville SSE

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Thanks GMTECH. It's a new O2 sensor, but that doesn't mean it's OK,, that happens too. Just in case it's not the O2 sensor or the wiring (I'll double check everything),, any other ideas?

 

Factory exhaust? This doesn't happen often, but the O2 sensor grounds through the exhaust, and if there is poor contact between the sensor and the exhaust, or the exhaust to the block, you can have screwy readings. But then, whos to say you may have gotten a bad sensor? Could also be a bad ECM. Now that I re-read your original post, make sure you didn't pinch the O2 sensor wire anywhere. The O2 sensor creates its own voltage, and if it gets shorted to ground, the ECM will read 0mV and think it is running lean. Check it out.

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"I used to have a handle on life, but then I used it as a plunger and broke it" -The Wave

ASE Master Tech + L1
Savannah, GA
'87 Trans Am-K&N,Cold air induction, SSM SFC, Boxed LCAs, 8mm Accel wires, Flowmaster, 16" GTA rims.
'97 Bonneville SSE

If you live in Southeastern US, check us out!
South East Thirdgen