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I am posting this for my son. He is working on a 97 chevy at work. He replaced the spider with the upgrade mpfi setup due to the spider leaking really bad. Found a fouled plug, replaced it. Found a bad plug wire, replaced it. Checked extensively for vacuum leaks, none found. He also checked timing, cam-crank at 0, it runs, but backfires thru the exhaust and has no power. What is next?
pulled power from the PCM to reset fuel trims? it's possible that it had to learn so far off due to the crap spider system that with a proper fuel injection scheme that it's running really rich/lean and the O2 won't correct for it.
From that discription I would be looking at an exhaust valve, but he's a tech isn't he? Would have done compression test?
How bad was it? Bad spider and bad plug, is the exhaust pipe full of fuel? Sniff the dipstick and see if it smells of gas usually the oil will be contaminated when flooded this bad.
Can't expect it to run good back firing. Can you image what the O2 sensor is seeing?
HTH!
Is the catalytic converter still in tact? Imagine that thing soaked in fuel and then getting hot.
Compression test 170-175 across the board. It does have a grey Napa distributor cap on it. Going to parts warranty that in the morning.
SOLVED!!! sure enough, it was the distributor cap.
:thumbsup:
The Vortec cap and rotor came up in another thread as a known possible issue. High tech distributor cap like LT1, lots going on in them compared to in order rotation type.
crab caps are really crabby like that.
But they look really cool!
Hard to believe they tried and succeeded to reroute 40,000 volts without crossfire... most of the time... I've been wanting to datalog cylinder misfires in my new Vortec truck.
The really bizarre part was that it wasn't logging misfires, it just ran really poorly. He put a new cap on, and it ran like a scalded cat. The truck made it for about an hour before it blew a heater hose!!! LOL. The owners were really happy when they got back from their camping trip, the truck got the best fuel economy ever and it was pulling a 25 foot travel trailer.