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How many missfires are normal in a drive cycle?

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Old Mar 20, 2009 | 03:12 PM
  #1  
corners's Avatar
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An RX ate my baby
 
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From: A swirling eddy of electronic mayhem
Question How many missfires are normal in a drive cycle?

I've got an '06 GT 6MT, I bought it new and it now has 30k on the clock. I changed the spark plugs about 6 months ago, and I have kept up with the flash updates.

I run 89 octane 76 gasoline, I get better gas mileage with that than 91 super and it doesn't knock.

I got an OBDScan-Apex for my birthday with the RX8 specific software and I've been playing with it. I've never had a CEL and the car runs fine.

I've got an average of 11 missfires for rotor 1 and 4 missfires for rotor 2 over the last 10 drive cycles. Is this normal?
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Old Mar 20, 2009 | 03:14 PM
  #2  
dozer's Avatar
on his 3rd rx8
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From: santa ana, ca
i dont think so...ive only had like 1 misfire in 2 years...my CEL blinked then turned off...never had misfire since then
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Old Mar 20, 2009 | 03:18 PM
  #3  
corners's Avatar
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An RX ate my baby
 
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From: A swirling eddy of electronic mayhem
Originally Posted by dozer
i dont think so...ive only had like 1 misfire in 2 years...my CEL blinked then turned off...never had misfire since then

Note that my CEL has not blinked, either. I think you have to have multiple missfires in a row to make the CEL blink. Monitoring the OBDII port while driving only gives me a single missfire when I romp on it really hard.
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Old Mar 20, 2009 | 03:22 PM
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on his 3rd rx8
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From: santa ana, ca
hmmmmmm i dont know then
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Old Mar 20, 2009 | 07:37 PM
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teknics's Avatar
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From: Wayne, NJ
avg of 11 misfires and 4 misfires over 10 cycles?
What about on the 1 previous drive cycle?

The rx8 requires a LOT of misfires to trigger the CEL light and a 0300-0302 misfire code.

11 and 4 is about normal really, your car will always misfire on startup and turn off, misfires happen all the time really. a major/dead misfire is different then a regular misfire. Minor misfires are quickly and easily adjusted for by the pcm, and fully expected.

I think you need to be in the 100's to trigger a CEL, i've seen cars come in with close to and over 100 misses on the previous drive cycle and they dont even notice and the light doesnt go on. I generally check coils and replace plugs when i see that. That's one of the specs that gets widen with the PCM flashes on these cars, it used to be a close tolerance but mazda realized that was a bad idea. On piston cars the misfire light is trigger with only a few misfires, on the speed6 all you need is 1 single misfire to set a light lol.

kevin.
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