Constant Misfire...
Thread Starter
Instructor
Joined: Nov 2009
Posts: 120
Likes: 0
From: Miami FL
Constant Misfire...
I'm stumped I keep pulling code I think p0300 multiple engine misfire. I decided and changed my plugs and wires, went all stock. I checked all their gaps and installed but still showing the same results and the engine runs rough at idle but a better if I rev it up and if Im cruising at let say 70mph I can feel a slight sutter every oncein a while like a jerking sensation. I dont know if maybe one of the coils are bad? any help would be highly appreciated thank you =/
Team Owner
Joined: Feb 2001
Posts: 27,228
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From: Short Hills, NJ
Tech Contributor
Joined: Mar 2003
Posts: 12,094
Likes: 197
From: Colorado Springs, CO
St. Jude Donor '08-'09-'10-'11
I'm stumped I keep pulling code I think p0300 multiple engine misfire. I decided and changed my plugs and wires, went all stock. I checked all their gaps and installed but still showing the same results and the engine runs rough at idle but a better if I rev it up and if Im cruising at let say 70mph I can feel a slight sutter every oncein a while like a jerking sensation. I dont know if maybe one of the coils are bad? any help would be highly appreciated thank you =/
Hope this helps.
Tech Contributor
Joined: Mar 2003
Posts: 12,094
Likes: 197
From: Colorado Springs, CO
St. Jude Donor '08-'09-'10-'11
In my case the debris fell out when I removed the inj and turned it over. It fell onto my shop counter.
Thread Starter
Instructor
Joined: Nov 2009
Posts: 120
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From: Miami FL
You dont have to buy any if you can scan by cylinder. Just see which cylinder is misfiring (its not all of them) and swap that injector with a neighboring one. If the scan shows it jumped then its the injector.
In my case the debris fell out when I removed the inj and turned it over. It fell onto my shop counter.
In my case the debris fell out when I removed the inj and turned it over. It fell onto my shop counter.
I can't scan by cylinder... will be investing in hp tuners in the future
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Team Owner
Joined: Feb 2001
Posts: 27,228
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From: Short Hills, NJ
I agree, I wouldn't buy new O2s just yet, it could definitely be a bad injector or possibly even more simple, perhaps just an unplugged injector (check the little electrical harnesses/wiring by the fuel rail at the top of each injector).
Safety Car
Joined: Jun 1999
Posts: 3,570
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From: Austin, Singapore, Kuala Lumpur, Houston, Dallas, Hong Kong, Elgin, etc.. Texas
Another trick is to get one of those temperature laser guns to locate which cylinder is missing. Point at the exhaust header. $40 at Harbor Freight but there are others out there.
One time, using this we determined which cylinder had the miss. We swapped plugs, coils, and injectors around and nothing changed. So we we figured it must be in the wiring. We found the wire to the injector was broken in 2 spots.
One time, using this we determined which cylinder had the miss. We swapped plugs, coils, and injectors around and nothing changed. So we we figured it must be in the wiring. We found the wire to the injector was broken in 2 spots.
Tech Contributor
Joined: Dec 2006
Posts: 10,962
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From: Van Buren Arkansas
Wounded Warrior Escort '11
I don't know about the C-6 even though I have an '07, but from the C-5 world, when we see a P0300, the first thing I suggest is the coil grounding at the rear of the driver's side head. Usually, its come lose therefore all cylinders are impacted with the misfire. So saying that, I've not gone out and looked at mine to see if its got the same ground as the C-5's but it probably does or somewhere similar. Somehow, the coil packs have to get grounded and that's where I would be looking for that code.
Melting Slicks
Joined: Sep 2008
Posts: 2,360
Likes: 59
From: San Jose California
Like Spin said, get it scanned correctly. I just fixed a GTP for a friend who was quoted $1500.00 to fix his car by a local garage. If you went by all the error codes that popped up that seemed correct. My EZ scan 6000 actually lets you see individual cylinders, All misfires were on cylinder #3. Mine was little easier due to the fact that the injector itself was open, found a set of reman'd injectors (due to mileage on the car) and done. So, it is a great help if you can find someone to help you out.
DJ
DJ
Heel & Toe
Joined: Jan 2010
Posts: 23
Likes: 0
From: Fleming Island Florida
I have an 06 and have a similar problem. I have a periodic rough idle(about 3 times per week) usually with check engine light iluminated. I took it by Advance and they gave me a PO300 code. Ran a can of Lucas injector cleaner through it and one day later, it cleared up and light went off. About 2 days later the rough idle started again and light back on. It runs fine(or seems to) when you jump on it, but idles rough as hell. Took it to dealer and they told me that their scan showed two injectors were clogged. They injected some kind of cleaner under pressure through the fuel line via a Shrader valve. Resulted in leaking Shrader valve on fuel line. Dealer replaced the Shrader valve and told me it was fixed. WIfe picked it up yesterday PM. I Drove it to work this AM and within one mile VOILA, rough idle and check engine light back. Any ideas??
