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MIL w/O2 codes: need help w/diag & ID'ing sensors

Background info: 1996 Chev 1500 4WD pickup w/305 & A/T. MIL on. Plugs, cap, rotor, air filter recently replaced. Truck starts well and runs well when cold. After 3-10 minutes of warm-up begins to run very roughly (including misfire pops if too much throttle used). Then will abruptly begin to run well again as if a switch was thrown. Will continue run well until engine turned off and then restarted after a few minutes pause, after which the cycle will repeat.

A scan pulls the following OBDII codes, which reoccur (along w/MIL) if cleared:

P0137 O2 Sensor Circuit Low Voltage (Bank 1 Sensor 2) P0152 O2 Sensor Circuit High Voltage (Bank 2 Sensor 1) P0154 O2 Sensor Circuit No Activity Detected (Bank 2 Sensor 1) P0155 O2 Sensor Heater Circuit Malfunction (Bank 2 Sensor 1) P0304 Cylinder 4 Misfire Detected

I'm looking for diagnostic suggestions, and help ID'ing the sensors/banks mentioned in the codes as well as in any posts in this thread. I'm very interested in your take on what role the catalytic converter might play in generating the codes, because I've had conflicting feedback there from several experienced sources.

Thanks. - KS

Reply to
ksnh
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Generally the converter does not play a large roll here. The O2 sensors are ignored for a while during engine warm up and then are used to control mixture after the fact. You might also check you engine tempature sensor to see if it is in spec even though it is not coding as it can through mixture off and cause O2's to go a bit nutz at times. As far as the misfire, I would not be concerned because I am sure it will clear when the O2 problem is corrected unless you havelow compression of one cyclinder and it is sending extra raw gas into exhaust and messing up sensors.

----------------- The SnoMan

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Reply to
SnoMan

I'd look for blown fuses that feed the injectors. Not sure if quad drivers do this, but look into that. Quad drivers are in the computer and are used to provide switched power, or PWM power to various emission related devices. KenG

Reply to
KENG

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