2000 Boxster S slight missfire
09-08-2021, 03:58 PM
#1
1st Gear
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2000 Boxster S slight missfire
Hi Guys,
my 986s has an issue. When the car idles it seems like it is misfiring every so often. It is very
minor and it doesn’t want to stall.
This goes away with normal driving, the car pulls strong, I don’t think is it lacking power, it pulls smooth, and It still does over 165mph /265kmh.
When I cruise at a constant speed on the highway I feel like it misfires every so often as well.
The plugs and coils have been replaced in 2017, or about 15000kms ago.
Could this be a MAF sensor or AOS issue? The car did blow some smoke with a cold start, but that has gone away on its own.
I figured this could have been because it has been driven very little between March of 2020 and februari of 2021.
My car is a 2000 986s, 6 speed with just under 200k kilometers or 120k miles.
my 986s has an issue. When the car idles it seems like it is misfiring every so often. It is very
minor and it doesn’t want to stall.
This goes away with normal driving, the car pulls strong, I don’t think is it lacking power, it pulls smooth, and It still does over 165mph /265kmh.
When I cruise at a constant speed on the highway I feel like it misfires every so often as well.
The plugs and coils have been replaced in 2017, or about 15000kms ago.
Could this be a MAF sensor or AOS issue? The car did blow some smoke with a cold start, but that has gone away on its own.
I figured this could have been because it has been driven very little between March of 2020 and februari of 2021.
My car is a 2000 986s, 6 speed with just under 200k kilometers or 120k miles.
09-12-2021, 03:29 PM
#2
How do you know it has a misfire? Are you looking at actual values in Durametric to see the # of misfires at each cylinder?
Without knowing for a fact of what it is or isn't doing isn't going to be helpful in troubleshooting.
it will NOT be a maf or AOS issue. Most likely it isn't actually misfiring or it's bad plugs/coils. Plugs after 15k miles are due anyway so might as well replace them cause they are also cheap.
Without knowing for a fact of what it is or isn't doing isn't going to be helpful in troubleshooting.
it will NOT be a maf or AOS issue. Most likely it isn't actually misfiring or it's bad plugs/coils. Plugs after 15k miles are due anyway so might as well replace them cause they are also cheap.
09-13-2021, 07:16 PM
#3
Rennlist Member
It's very easy to Not properly reconnect the wires onto the coils, I would check that 1st & then pull the plugs to see any that are not burning clean.
09-17-2021, 05:48 PM
#4
Agree with Byprodriver above, pull all your plugs and inspect the electrodes, they should all be the same gray/white ashy color. An obvious sign of misfire would be a black/sooty electrode. Ensure all your plugs are snug upon reinstallation, and that the coils are firmly seated on the plugs. If you do find a misfiring plug, and the plugs and coils are good, it may be a sub-par fuel injector that's partially clogged and not atomizing the fuel/air mixture properly. This would result in a misfire due to a lean condition in that cylinder. May consider running a can of fuel injector cleaner thru your tank before you dig any deeper. Best of luck.
09-19-2021, 03:43 PM
#6
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I've had the same issue, with P0456 code (slight evap leak) showing up. Then just this morning, it sounded rough and lumpy at idle and halfway through 2 mile drive it started spewing smoke out the back, blinking CEL, and all cylinders showed up as misfire codes. Can be a whole host of reasons for this from what I understand, maybe AOS... my sparkplugs are only 2 years old so I'd be shocked it was them, but I guess you never know...