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Old 10-26-2012, 10:17 PM   #1
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Default Odd misfire cruising in town

When I went from naturally aspirated to supercharged, all I had to change in the tune was the boosted cells and acceleration enrichments and the car ran great. I'm naturally aspirated again, and retuned the acceleration enrichments, but otherwise left the tune as is.

I've got 93 octane in my tank with some Chevron Techron.

Cruising around town today at about 3000rpm; 30-35mph , I got a series of misfires. I got out my phone and started logging, and was able to capture a few of the misfires.

Any advice in fixing this would be helpful. I never had any issues with misfires on this tune in the past. My cruise is usually around 15-15.5 AFR. The engine made a quick jolt, followed by the rich AFR dip.
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Old 10-27-2012, 01:24 PM   #2
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How old are your sparkplugs/wires/general ignition components? Can you pull the plugs and check their condition?
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Old 10-29-2012, 12:13 PM   #3
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Plugs and wires were replaced about a year and a half, less than 20,000 miles ago. I probably still have colder than stock plugs on the car, come to think of it.

I'll put new OE plugs in.

It's interesting in that it happened in 'normal' operation...the base fuel table VE value and ego correction acheived the AFR target I was commanding. My AFR targets in cruise are 15.5-15.8, and although it's worked in the past, I'll also trim these back to 15.3.
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