Chasing a miss.....again !!
Thread Starter
Burning Brakes
Joined: Feb 2013
Posts: 769
Likes: 95
From: Central Pennsylvania
Chasing a miss.....again !!
I've been chasing a miss. 92 LT1, had same issue last fall. Replaced OPTI(and the water pump), new plugs, new wires. NO luck 8 injectors from FIC.....problem solved. No problems all Winter. A month ago, miss came back. I started with the injectors, all OHM'd out OK. Removing one injector harness at a time made a difference in idle. Wires look good, no firework display under the hood at night. Miss only apparent when car is under a load. Runs great on start up. Seems like it only appears once the car is in closed loop. There is a rich fuel smell while running. Any thoughts ?
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
Check the fuel pressure regulator vacuum port to see if it has fuel in it. Pull off the vacuum line and turn on the ignition. If the fuel pressure regulator diaphragm is bad fuel will come out of the vacuum port.
Thread Starter
Burning Brakes
Joined: Feb 2013
Posts: 769
Likes: 95
From: Central Pennsylvania
Thanks, I'll check that out. I check fuel pressure, it was in the mid 40's. Held pressure.
Thread Starter
Burning Brakes
Joined: Feb 2013
Posts: 769
Likes: 95
From: Central Pennsylvania
The saga continues.... fuel pressure good at the rail, no leakdown. I was given the advice to change out the fuel pump. Would a weak fuel pump only exhibit a problem after the car has warmed up? For the first few minutes, the car runs great, then it starts "slightly" sputter on acceleration. Shifting into neutral, revving engine....nice and smooth. Although I put in new AC?Delco wires last fall, is it possible that one is misbehaving under the mass of equipment on the front of the engine. It was also suggested that I change out the ECM, easy to do, as costly as the Opti I put on last fall. My neighbor things it needs a 12ga adjustment ( He's a hunter and I think I get his drift). It's a shame, my '89 runs great but looks like cr*p.
Pro
Joined: Dec 2006
Posts: 557
Likes: 4
From: Austin Texas
The saga continues.... fuel pressure good at the rail, no leakdown. I was given the advice to change out the fuel pump. Would a weak fuel pump only exhibit a problem after the car has warmed up? For the first few minutes, the car runs great, then it starts "slightly" sputter on acceleration. Shifting into neutral, revving engine....nice and smooth. Although I put in new AC?Delco wires last fall, is it possible that one is misbehaving under the mass of equipment on the front of the engine. It was also suggested that I change out the ECM, easy to do, as costly as the Opti I put on last fall. My neighbor things it needs a 12ga adjustment ( He's a hunter and I think I get his drift). It's a shame, my '89 runs great but looks like cr*p.
In addition to searching the Forum I've run literally hundreds of scans of the car, talked with Gordon Killebrew and others and replaced a laundry list of items all to no avail.
I've seen dozens of similar tales. Some have happy endings and some seem to go on and on like yours and mine. But I'm an eternal optimist so I'll keep tuned in case someone has a new idea that works.
Good luck! John
Thread Starter
Burning Brakes
Joined: Feb 2013
Posts: 769
Likes: 95
From: Central Pennsylvania
Problem solved. Looked under the hood at night. No fireworks, but some sparks occasionally on pulleys for the a.c. and alternator. I bit the bullet and pulled the alternator, moved ac compressor out of the way. Removed idler pulley and tensioner. Clear shot of the plug wires. 3 wires were rubbed down to the center. CAREFULLY replaced all 4 on the bank, reinstalled everything. Fired it up.........perfect. long road test......perfect. I just replaced all 8 wires last fall. I guess I wasnt careful enough when I routed the wires. Lesson learned.
Last edited by skyhawk50; Jul 1, 2014 at 09:59 PM.
Pro
Joined: Dec 2006
Posts: 557
Likes: 4
From: Austin Texas
Problem solved. Looked under the hood at night. No fireworks, but some sparks occasionally on pulleys for the a.c. and alternator. I bit the bullet and pulled the alternator, moved ac compressor out of the way. Removed idler Paul k eyes and tensioner. Clear shot of the plug wires. 3 wires were rubbed down to the center. CAREFULLY replaced all 4 on the bank, reinstalled everything. Fired it up.........perfect. long road test......perfect. I just replaced all 8 wires last fall. I guess I wasnt careful enough when I routed the wires. Lesson learned.
Thread Starter
Burning Brakes
Joined: Feb 2013
Posts: 769
Likes: 95
From: Central Pennsylvania
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