Misfires under load, needs some input - Page 4 - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


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Old 01-11-2009, 06:17 PM   #31
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Ok, checked the coil packs cold. Primary is .7 (.5 - .7) secondaries are 9.79, 9.79 and 9.41 (5 - 11). Moved the #6 wire away from the O2 sensor wiring. Tested the ignition module. It checks out fine. Could it be something in the boost control path. The car runs strong unless I take the boost to the right side of 0 on the boost gauge. Any past 0 causes it to missfire and fall on it'* face. Doing flow testing on the cat tomorrow. I am at a loss here. Checked all the vacuum lines that I could find. Just Seafoamed it, we'll see what that does. Any other ideas would be greatly appreciated.


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Old 01-11-2009, 06:29 PM   #32
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This is starting to be a real stumper here. A plugged cat is a possibility. Lets see what that shows.
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Old 01-11-2009, 06:38 PM   #33
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Seafoam didn't help the problem. Probably helped the clean the top out but didn't help solve any of this problem.

I can run the car up to highway speed as long as I stay outa the boost. I am not familiar enough with the setup to know if there could be a problem in the boost control system that causes this. It is getting around 20mpg on the highway.

Do the symptoms support a cat problem.


Btw just to refresh everyone. This problem started 90 miles after a plug/wire change. Could it be a bad plug wire? I still have the old set and am tempted to put them back in.


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Old 01-11-2009, 07:12 PM   #34
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Test your wires. And put the old ones back on. Pull the new plugs and inspect them. Look for one that is different from the rest.
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Old 01-11-2009, 07:36 PM   #35
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Just put the old wires back on. No change. Has a new set of AC Delcos in it now.

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Old 01-11-2009, 09:27 PM   #36
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We could use some input from billboost here. Where are you Bill?
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Old 01-11-2009, 09:56 PM   #37
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Hoping this question didn't get lost in all the mess.

Could there be something in the boost control path that is causing all this?


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Old 01-11-2009, 10:10 PM   #38
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Have you tried running with the supercharger belt off? It wont hurt anything. But if it still misses it may rule out the supercharger.
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Old 01-11-2009, 11:12 PM   #39
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Dan,
No, that was the next step after the check the flow in the cat tomorrow.


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Old 01-11-2009, 11:13 PM   #40
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Could the supercharger be causing all this?

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