random misfires code po300 help
Tech Contributor
Joined: Jan 2007
Posts: 19,530
Likes: 1,196
From: Dyer, IN
Tech Contributor
Joined: Jan 2007
Posts: 19,530
Likes: 1,196
From: Dyer, IN
What did the plugs you removed look like? Any indications of a funky cylinder that could help you isolate the problem?
You can inspect the injector connectors and harness to make sure it's not grounding out anywhere. Chances of a bad coil are possible, but a very rare possibility. Verify the correct fuel pressure at the rail. You can inspect the wiring to the crankshaft sensor, but I would expect a crankshaft sensor code if it was bad......always worth a look to be thorough, especially because you have headers.
A look at the G107 (attached to and behind the drivers side head). It provides grounds for both coil packs.
I also would not dismiss the possibility of a broken valve spring.
Since you have fresh plugs, you might pull them again to see if there is anything obvious in their appearance.
You can inspect the injector connectors and harness to make sure it's not grounding out anywhere. Chances of a bad coil are possible, but a very rare possibility. Verify the correct fuel pressure at the rail. You can inspect the wiring to the crankshaft sensor, but I would expect a crankshaft sensor code if it was bad......always worth a look to be thorough, especially because you have headers.
A look at the G107 (attached to and behind the drivers side head). It provides grounds for both coil packs.
I also would not dismiss the possibility of a broken valve spring.
Since you have fresh plugs, you might pull them again to see if there is anything obvious in their appearance.
Thread Starter
Intermediate
Joined: Apr 2005
Posts: 47
Likes: 0
From: atl ga
plugs looked good fuel pres 60psi pulsed all inj all good laser cked intake temp at the
base of the intake temp with in 20dg of each other pulled pass side valve cover springs
looked good cleaned mass air flow sen even put stock tb back on
base of the intake temp with in 20dg of each other pulled pass side valve cover springs
looked good cleaned mass air flow sen even put stock tb back on
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Le Mans Master
Joined: Nov 2005
Posts: 6,993
Likes: 25
You can't go by looks on injectors-take them out and have them flow tested and cleaned. I use www.cruzinperformance.com to do mine. He flow tests them before, clenas them and flow tests them again.
Burning Brakes
Joined: Dec 2006
Posts: 1,090
Likes: 80
From: Burleson Texas
These items may be visually/physically inspected:
Vacuum hoses, throttle body, intake manifold vacuum leaks
PCM grounds being clean and secure
Injector harness connectors are connected to proper injector
Inspect injector fuese for open fuse
Low pressure ( you checked this) or restricted fuel (filter)
Really sounds like a bad plug or plug wire (even though they are new). What made you change the plugs and coil pack? Was the car running good prior to the changes?