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In desperate need of help. Misfire issue.

   
Old 06-19-2018, 01:46 AM
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maybe try changing the plug wires?...sometimes its hard to see them arcing
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Old 06-19-2018, 06:17 AM
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You could try running a continuity check on the coil wiring harness back to the PCM connectors. Maybe some thing got pinched or burned.

check your plugs are torqued correctly and not cracked.

try changing your o2 sensor in that bank?
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Old 06-19-2018, 07:44 AM
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Originally Posted by Atomic
Well, thats the air portion...we are down to fuel or spark, and my money is on spark since 95% of the time on these engines a misfire is an ignition issue in my experience.
Is it possibly a timing issue? Could it just suddenly lose or skip timing, but not run enough to be popping and back firing?

Originally Posted by 01FormulaTA
maybe try changing the plug wires?...sometimes its hard to see them arcing
I'll give it a try on lunch and see what happens. I have swapped plug wires from cylinder to cylinder with no change.

Originally Posted by 2002_Z28_Six_Speed
You could try running a continuity check on the coil wiring harness back to the PCM connectors. Maybe some thing got pinched or burned.

check your plugs are torqued correctly and not cracked.

try changing your o2 sensor in that bank?
My o2 sensors are fairly new. I replaced the old bosch ones I had with some new factory a/c delco ones. As far as the wiring goes, could I have a wiring issue but still have spark? I have confirmed the dead cylinders are sparking.


I really appreciate all the help from everyone. I don't post much, but I have been lurking on this site for a long time. Lots of knowledge and great advice to be had here.
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Old 06-20-2018, 07:24 AM
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Well, still no luck. I tried some new plug wires to no avail. I took the intake manifold and valley cover off to see if I could inspect the cam for worn lobes. The cam looked in great shape. Its as if its mechanically in time but electronically out of time. I'm going to pull the starter today and see if i can inspect the reluctor wheel on the crank. Maybe it slipped? If I don't see anything there I may just throw a new crank sensor in it and see what happens.
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Old 06-20-2018, 11:08 AM
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Try a crank angle sensor error CASE relearn as well.
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Old 06-21-2018, 06:36 PM
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Originally Posted by 2002_Z28_Six_Speed
Try a crank angle sensor error CASE relearn as well.
Well, I gave it a try today, but I couldn't get past the first step. It would never hit the 4000rpm fuel cut off the tech 2 listed. It would just rev to the limiter. Any other guesses?
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Old 06-22-2018, 08:50 AM
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I would check your injector fuses and wiring. Make sure all injectors get power and have a good ground. If that's not it get the injectors tested somewhere or swap out or different ones?
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Old 06-23-2018, 10:25 PM
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Originally Posted by Forcefed81
Well, I gave it a try today, but I couldn't get past the first step. It would never hit the 4000rpm fuel cut off the tech 2 listed. It would just rev to the limiter. Any other guesses?
Did you have the e-brake set?
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Old 06-24-2018, 09:29 PM
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Originally Posted by 99ta


Did you have the e-brake set?
Nope I didn’t. I should have read the directions completely before I started. I replaced the oil pan gasket because it was leaking pretty bad. I checked the reluctor wheel while I had the pan off. It looked good and hadn’t slipped. I replaced the crank position sensor also and was able to complete the relearn procedure. Still misses.
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Old 06-24-2018, 09:56 PM
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Sounds just like the issue I’m currently having. Tried everything I can think of and mine still missing. I’m about to make a harness for the coils by themselves and repin them and try that.
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