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Random misfires while idling

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Old Feb 12, 2009 | 05:20 PM
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2002TransAmWS6's Avatar
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Default Random misfires while idling

Hey can someone give me a hint what to look for when I'm getting misfires on multiple cylinders while idling ?

Under load, while driving, no misfires.

No P0300 so far, but my interceptor gauges show it. It's up to 20 misfires in total, never more, sometimes only 2 or 4 or 8.
Idle is a little rough sometimes. Car is totally stock. 90.000 Mls.
I think it can't be fuel-related, I run the car on liquified petroleum gas as well, on separate injectors. Same Problem.

Got a P0135 today, new O2-Sensors are on the way.

Any help is appreciated, Thanks.
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Old Feb 12, 2009 | 05:52 PM
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Probably excessive spark plug gap. Anything over .055" can cause problems. Best solution would be some NGK TR-55 copper plugs closed down to .040"
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Old Feb 13, 2009 | 04:51 AM
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Ok, the spark plugs are about 1 month old, .050 gap. Copper plugs, from Champion, don't know if they are any good.

I wonder why it only happens at idle.
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Old Feb 14, 2009 | 12:52 PM
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Did the problem exist before the plugs? Champion and Bosch should not be used under any circumstance. Use AC Delco, NGK, or Autolite.
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