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Multiple misfires!!

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Old 09-15-2014, 11:27 PM
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ascastil
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Default Multiple misfires!!

Was setting up the shift light on my Aeroforce scangauge when I happened to notice some misfires. They were all over the place. Cyl 1, 2, 6, 8, etc. They didnt stay for long, it would show a misfire and then it would be gone. Checked the DIC, no codes. Car runs fine.

I have a few wires that were really close to the primaries, but I have those 2 primaries wrapped in header wrap and the heat sock things on all wires.

If it was a true misfire, does that mean the coil isnt firing? I would think if I had a melted wire it wouldnt show misfire. Maybe my scangauge is high?
Old 09-16-2014, 07:01 AM
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Cybermind
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Intermittent misfires will usually not leave a code in the DIC. However, when they happen, you should see a flashing CE light on the dash. Have you noticed an intermittent Check Engine while driving? If not, then they probably aren't genuine misfires.

PS: Have you changed your Crank Position Sensor recently? If the relearn process isn't performed after a CKP change, the DIC may report false misfire information.

Last edited by Cybermind; 09-16-2014 at 07:30 AM.
Old 09-16-2014, 11:54 AM
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ascastil
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No CEL flashing whatsoever. Havent touched the CPS either. I dont think its misfiring, cant understand why my scangauge says it is.
Old 09-16-2014, 04:01 PM
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3boystoys
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Originally Posted by Cybermind
Intermittent misfires will usually not leave a code in the DIC. However, when they happen, you should see a flashing CE light on the dash. Have you noticed an intermittent Check Engine while driving? If not, then they probably aren't genuine misfires.

PS: Have you changed your Crank Position Sensor recently? If the relearn process isn't performed after a CKP change, the DIC may report false misfire information.
Not true, P0300 is random misfire code, the DIC will only show this, better scanners will show you which cylinders are involved.
Old 09-17-2014, 06:05 PM
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American Heritage
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Large camshaft will cause the scanner to see intermittent misfires at idle. Its also common on some C5/C6's to see intermediate misfires at idle. How old are your plugs/wires? how many miles on the engine?
Old 09-18-2014, 01:48 AM
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ascastil
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Stock cam. Plugs and wires are not that old. GM wires, NGK TR6. A&A supercharger, longtubes, axle back. Stock besides that.

I actually googled a very vague "Aeroforce scangauge false misfires" and had plenty of results from different platforms, Trailblazer SS was one of the forums. Seems this isnt uncommon. Everybody who seems to be complaining about it has a car thats running fine. Im not going to worry about it I dont think. Once it starts backfiring and bucking I will, lol.
Old 09-18-2014, 08:01 PM
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2003Evo
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Originally Posted by 3boystoys
Not true, P0300 is random misfire code, the DIC will only show this, better scanners will show you which cylinders are involved.
Also not true ...if the P0300 is continuous for certain amount of time then the CEL will flash like crazy as cybermind mentioned above...in this case you need to stop asap other wise you could damage the engine..
As far as this case, it could be counting up the misfire on those cylinders due to the cam timing
Old 09-19-2014, 09:28 AM
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3boystoys
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Originally Posted by 2003Evo
Also not true ...if the P0300 is continuous for certain amount of time then the CEL will flash like crazy as cybermind mentioned above...in this case you need to stop asap other wise you could damage the engine..
As far as this case, it could be counting up the misfire on those cylinders due to the cam timing
It will post a P0300 and possibly P030[1-8].

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