1993 JGC 5.2l/V8

[mahimahi]

Hi everybody, i have a good one, maybe somebody can help. My GC starts fine, idles fine, after aprrox 15min(on the dot allmost), im assuming operating temp, it starts to hesitate, sputters, backfires with black smoke, running very rich, and no throttle response whatsoever, then it may all of a sudden rev way up and then down again until it stalls. Nobody can figure it out. I get no check engine light on or no codes. I replaced the following: Fuel pump, map sensor,iddle air sensor, dist cap, rotor, pickup,sparkplugs and wires, cleaned injectors. These are all brand new and didnt make difference, oh also the ECM, if anybody has a clue please advise, im very desperate.

Thanks

[dksob81]

Sounds like possible O2 Sensor effects.

Seeing that the PCM doesn't use the reading from the 02 Sensor until it reaches 600+ degrees, the 15 minute wait would sound about right for the O2 sensor to get to proper operating tempature.
You just have one O2 sensor right before the catalytic converter on the exhaust, passengerside...

[mahimahi]

Thanks i am going to check it out.

[teemsta]

try changeing the coil also