Please help: G35 p0300 problem
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From: KY tri state area/FL keys
had same problem after pulling then reinstalling my motor last winter..coils got mixed up,problem solved..im assuming this was the cause of the problem in this case as well..but i was under the assumption the p0300 code was a vacuum leak?!?
I have a very similar problem that began with P0300, and after replacing fuel injectors 3x, and MAF I'm now getting a P0305. Since the code was being reported on cylinder 5 consistantly at this point it was diagnosed as either the ECU or wire harness. Replaced the ECU no dice so next up is the wire harness...
Joined: Apr 2010
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From: Pittsburgh PA
the after cat on that cylinder head was clogged causing the multiple cylinder misfire code when i took my y pipe off to fit the stillen y pipe and cat back exhaust i pulled out a baseball sized chunk of metal....ever since problem solved no misfire no problems at all
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I have an multimeter and a 06 manual tells me where everything is my bad on not knowing you have an 03 the wiring will be different, search the forum i got it there might take a while but you'll know 4 sure. 2nd option get, borrow a multimeter take a coil pack plug off and check (all 3 wieres to ground) 1 will be ground, if it reads high ohms even 5 ohms U found your problem. I have made mine perfect and omg acceleration. Clean the bolt with NAPA QD cleaner and bolt hole to with nQ-tip let me know what U did
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Joined: Jul 2011
Posts: 31
Likes: 2
I have an multimeter and a 06 manual tells me where everything is my bad on not knowing you have an 03 the wiring will be different, search the forum i got it there might take a while but you'll know 4 sure. 2nd option get, borrow a multimeter take a coil pack plug off and check (all 3 wieres to ground on plug) 1 will be ground, if it reads high ohms even 5 ohms U found your problem. I have made mine perfect and omg acceleration. Clean the bolt with NAPA QD cleaner and bolt hole to with nQ-tip let me know what U did
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Joined: Jul 2011
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I'll show U my 06 g35X coil and 2 transmission ground points
solder everything 
This is the cure every problem my car had except 4 1, the carbon is done with water injection not enough pics yet i will show U the pump. 
this is an RV 12V pump 250 psi and a 1 GPH (gallons per hour) nozzle on an NA G35X. this will keep U thinking 4 a while.
really gonna like this 1 
solder everything This is the cure every problem my car had except 4 1, the carbon is done with water injection not enough pics yet i will show U the pump. this is an RV 12V pump 250 psi and a 1 GPH (gallons per hour) nozzle on an NA G35X. this will keep U thinking 4 a while.really gonna like this 1
Last edited by wiredG35; Apr 30, 2012 at 11:52 PM. Reason: verbage and pic
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To eliminate manual mode lag in up-shifting, but still auto kicks *** on manual and holds it in gear for a few seconds when hard driving. I can do 0-60 in 5 sec with these mods. Trying 2 share for those who don't want FI and the money it costs.
Did you check the gap on your spark plug? What spark plugs did you get - models would be helpful. If they're the platinum plugs like recommended in the manual (PLFR4A-11, PLFR5A-11, or PLFR6A-11) you should be gapping them to 0.044". They are supposed to come pre-gapped (to 11mm or 0.433 inches, as is shown by the model number) but sometimes when they're being moved the gap gets adjusted.
That would be the first thing I'd check. Secondly, remove your engine cover and intake and check to make sure you have the cylinders corrected in the right firing order! You may not think you could actually mess this up but when I changed my spark plugs I did switch 4 and 6 on accident as I was talking to a friend of mine. Started it up and it immediately felt rough and went ahead to switch them.
If you look at the harnesses going to the ignition coils, there will be two wires with the same color and the wire that is on top (when the harness is connected to the coil) should be different on each one. This is the ignition signal wire going to your ECU. If everything is wired up correctly, cylinders 4 and 6 should have the same color wire, but 6 should have a red tracer and 4 should not. If you see a tracer on the harness connected to 4, switch them. Because of the way the connections come off of the main harness, it can be easy to switch the two if you're not paying much attention.
Lastly - try not to drive your car much in this condition. Misfires and can be detrimental to the life of your engine. Try to diagnose it before you continue driving.
That would be the first thing I'd check. Secondly, remove your engine cover and intake and check to make sure you have the cylinders corrected in the right firing order! You may not think you could actually mess this up but when I changed my spark plugs I did switch 4 and 6 on accident as I was talking to a friend of mine. Started it up and it immediately felt rough and went ahead to switch them.
If you look at the harnesses going to the ignition coils, there will be two wires with the same color and the wire that is on top (when the harness is connected to the coil) should be different on each one. This is the ignition signal wire going to your ECU. If everything is wired up correctly, cylinders 4 and 6 should have the same color wire, but 6 should have a red tracer and 4 should not. If you see a tracer on the harness connected to 4, switch them. Because of the way the connections come off of the main harness, it can be easy to switch the two if you're not paying much attention.
Lastly - try not to drive your car much in this condition. Misfires and can be detrimental to the life of your engine. Try to diagnose it before you continue driving.
