Hi, I just bought a 96 Jimmy in hopes that it was an easy fixer upper. It did not start when i bought it. Turned out the battery was just bad. But that was just the start to its troubles. It has black smoke when you rev it up and it will backfire . Has loss of power, NO engine noises though. I get the same code over and over P0300 wich is multiple cylinder misfire. So i changed the spark plugs, wires , rotor, cap.(used AcDelco) And did not help. Also changed ECU, Coil, Fuel Regulator, Map,Maf, Cleaned EGR, NOw I have Four more codes.. from letting it run for a half hour in the driveway.. They Are
-P0134 O2 Sensor circuit No activity detected
-P0146 O2 Sensor circuit No Activity detected
-P0152 O2 sensor circuit High voltage
And i got a code for transmission Solenoid "A" ??
So my question is are the O2 sensors bad? (there kinda expensive
and what solenoid is the "a"
I have done fuel system check... There is no problem with the fuel sytem.
And i have replaced ALL secondary ignition components..
Thanks for any help!!!

 

P0134 - HO2S Circuit Insufficient Activity Bank 1 Sensor 1
P0146 - HO2S Circuit Insufficient Activity Bank 1 Sensor 3
P0152 - HO2S Circuit High Voltage Bank 2 Sensor 1

There are two solenoid A codes that are posted:
P0751 - Shift Solenoid A Performance or Stuck Off
P0753 - Shift Solenoid A Electrical

Having all of those O2 sensor codes would lead me to believe that there is a problem with your grounds or other associated wiring to/from the O2 sensors.