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Old 02-26-2012, 02:21 PM   #1
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Default Misfire problem

just joined up at this forum to see if I can get some help with a problem.

I have a 1994 Regal GS with the 3800, the engine has a misfire on #6 but only when I'm stopped at a light, the car runs fine otherwise. no problems until about 2 weeks ago. Thought maybe I got some bad gas so I put in Heet on one fill up and some STP fuel inj cleaner on another.

I have changed the plug, wire, injector, checked coil pack, checked for leaks on intake even though I replaced all the gaskets last March. Anyone know what my injector should read because I thought about checking to see if I have a partially broken wire on that cylinder. Also going to check compression on cylinder to see if maybe a valve is bad.

Any ideas or suggestions would be welcome,

Thanks, Jim
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Old 02-26-2012, 02:30 PM   #2
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That would be my next step is to check compression.Or pull the valve cover off and inspect the spring for #6
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Old 02-26-2012, 10:21 PM   #3
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Very odd the misfire only happens at idle. Did you scan a p0306 code? Is the CEL flashing?

Sounds like you are doing all the right stuff. In addition to checking compression and pulling the rocker cover to examine the valve springs, you might want to put a noid light on the #6 injector to see if it is getting a steady signal, preferably when the engine is misfiring. You can make a noid light with a 12 volt bulb if you get the type with the wires that can be straightened out. If the injector is not getting a steady signal you could have a wiring or ECM issue.
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Old 02-26-2012, 10:41 PM   #4
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The 94 and 95 are known for having odd ECM problems. If all else checks out, it could be the ECM. You mentioned you check the coil for 6, try swapping that coil with a different one and see if the mis stays on 6 or moves.
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Old 02-27-2012, 03:10 AM   #5
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I forgot to mention that I swapped out the coil with another one and also ran a scan, only code was p300 and the scanner said it was #6. am going to try the node test tomorrow also to see if I might have a bad wire somewhere.

Thanks again.
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Old 02-27-2012, 07:51 AM   #6
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p0300 is random misfire. How did the scanner tell you it was #6. For that you should have gotten a p0306 code.
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Old 02-27-2012, 08:00 AM   #7
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if the other checks dont reveal anything 306 was what i was getting when my intake went. coolant was slowly dripping in cyl 6. the amount of coolant i was loosing was very small so i thought they were unrelated at first.
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Old 02-27-2012, 11:29 AM   #8
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It was a scanner where you can run it while the engine was running. I went through the promps and it told me #6. Does anyone know what the voltage should be on the injectors?
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Old 02-27-2012, 12:18 PM   #9
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Quote:
Originally Posted by blkhwk7 View Post
It was a scanner where you can run it while the engine was running. I went through the promps and it told me #6. Does anyone know what the voltage should be on the injectors?

Check all 6 to see if one is different than the others.

A P0300 is a random misfire. P0306 is a misifre on cylinder 6. If this is a random misfire instead of a cyl 6, your scanner may have you tracking the wrong problem.
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Old 02-27-2012, 05:50 PM   #10
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I changed wires today, checked and cleaned all connections on the coil packs and icm. couldn't do a compression check because I couldn't get it to screw into the cylinders.
I listened to each side with a mech scope and didn't hear anything out of the ordinary. The only code is 300, which is a misfire, SES light is not on, runs fine over about 1500 rpm'*.
re scanned with the scan tool and it now says 4 and 6 are misfiring. I think the problem might be the ICM. going to try swapping that tomorrow.
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