Misfire codes keep popping up
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11 Second Club
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Joined: Jan 2002
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From: Indianapolis Area
Misfire codes keep popping up I am trying to tune my 402 N/A before I install the blower. I actually been getting misfire codes since the H/C package I had on the car last year. This motor is more important since it is installed. I checked the plugs and they were not blackened. I had the gap at .035" and after checking them I reduced them to .030" to see if it helps. Still misfire codes. It is even turning on the SES light. All I am doing is the part throttle tune. Any ideas on what I can do to fix it?
You have to understand that misfire detection is set up for a stock engine with a stock cam. It uses a complex formula based on the acceleration rate of the crank reluctor wheel. Misfire detection is required by the EPA because too many can damage the cats. When you put in an aftermarket cam, especially something like the one in your sig, the stock misfire detection goes out the window. What the stock misfire detection PCM perceives as a misfire is just the lopieness of your cam, rocking the crank reluctor in a not so stock manner, not actual misfires. Your best bet is to just set all the values in the tables at their max values.
