eyesi
OBS Enthusiast
Backfires thru the intake, you should suspect timing.Retarded spark timing can cause backfiring through the intake.
Also, are spark plug wires well routed?
VCM (powertrain control module) grounds and power circuits test must be checked if other mechanical issues are fine.
VCM connector 1 blue, 2 red, 3 clear or gray and 4 black.
http://troubleshootmyvehicle.com/gm/4.3L-5.0L-5.7L/pcm-connector-pin-outs-1996-1997-page-1
check ground wires at VCM blue connector pin 17-18 , if you get no a lecture near to zero ohms there, with battery positive disconnected, then ground that 2 pins, if you want near the connector. When they said check computer grounds , check them at the end of the VCM or PCM or ECM connector is the only way reliable to me, and is a very very common issue at computers related failures
Also, are spark plug wires well routed?
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Exhaust restricted, you can put a low scale manometer in oxigen sensor hole.VCM (powertrain control module) grounds and power circuits test must be checked if other mechanical issues are fine.
VCM connector 1 blue, 2 red, 3 clear or gray and 4 black.
http://troubleshootmyvehicle.com/gm/4.3L-5.0L-5.7L/pcm-connector-pin-outs-1996-1997-page-1
You must be registered for see images attach
check ground wires at VCM blue connector pin 17-18 , if you get no a lecture near to zero ohms there, with battery positive disconnected, then ground that 2 pins, if you want near the connector. When they said check computer grounds , check them at the end of the VCM or PCM or ECM connector is the only way reliable to me, and is a very very common issue at computers related failures
You must be registered for see images attach
You must be registered for see images attach
You must be registered for see images attach
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