P0300 Question
Thread Starter
Instructor
Joined: Apr 2007
Posts: 235
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From: Uniontown Pennsylvania
P0300 Question
Hey guys
I'm getting a random multiple misfire code.
2008 C6 with 28,000 miles with stock motor.
After letting the car sit for about 2 months this code happened today. The car drove fine last time I parked her a month or two ago. I can feel the car missing going down the road early on at 30mph, doesn't want to shift and starts sputtering (auto) During this episode sometime it triggers a service traction system but then that clears itself away but left with the misfire.
Can plugs go bad with this low mileage? If it was a specific plug or plugs, wouldn't I get a code specifying which cylinders are at fault?
Thanks for any help ahead of time.
*UPDATE*
I've since cleared the code and now PO307 is showing for cylinder 7 misfire. Should I just replace the one since the miles are so low or just replace them all? NGK plugs ok or should I go with AC Delco?
I'm getting a random multiple misfire code.
2008 C6 with 28,000 miles with stock motor.
After letting the car sit for about 2 months this code happened today. The car drove fine last time I parked her a month or two ago. I can feel the car missing going down the road early on at 30mph, doesn't want to shift and starts sputtering (auto) During this episode sometime it triggers a service traction system but then that clears itself away but left with the misfire.
Can plugs go bad with this low mileage? If it was a specific plug or plugs, wouldn't I get a code specifying which cylinders are at fault?
Thanks for any help ahead of time.
*UPDATE*
I've since cleared the code and now PO307 is showing for cylinder 7 misfire. Should I just replace the one since the miles are so low or just replace them all? NGK plugs ok or should I go with AC Delco?
Last edited by deathcharge; Jul 26, 2019 at 08:29 PM. Reason: update
Instructor
Joined: Jan 2018
Posts: 163
Likes: 17
Well New battery and still misfiring
Mainly cylinder 7 but few on others cylinders alsoSame problem so
To sum UP it IS not the battery, coils, plugs, plugs wires, valve spring and injectors
I forgot to mention it is during accélérations
what should I look then ? O2 sensors maybe ?
Mainly cylinder 7 but few on others cylinders alsoSame problem so
To sum UP it IS not the battery, coils, plugs, plugs wires, valve spring and injectors
I forgot to mention it is during accélérations
what should I look then ? O2 sensors maybe ?
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From: Cape Coral, Florida
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Moderator, Tech Contributor
Joined: Sep 2013
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From: Cape Coral, Florida
I vaguely remember your post... are these single cylinder or multiple cylinder misfires ???...can you can actually FEEL them or you just have a flashing MIL under load ??...if you changed everything in the ignition system for instance you can have a bad trigger signal from the PCM to a coil pack which would require a PCM replacement...without a scope and other specialized diagnostic equipment you’ll be chasing your tail trying to find an issue like this one !!...since you crammed this thing I may check that...again some specialized equipment needed where you would not have to disassemble the engine.
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,615
Likes: 4,062
From: Cape Coral, Florida
You didn’t mention about the O2 stuck RICH at 1048mv !!...while the engine is running pull off a vacuum line and try to drive it lean...if it now goes lean (below 450 mV) it may just be a bad O2 sensor...you can also tell by looking at the downstream O2 sensor...if it were truly rich the downstream O2 would be also be rich...just compare it to the other bank.
Last edited by C5 Diag; Dec 12, 2020 at 02:55 PM.