P0300 Random Misfire...HELP!
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From: Jacksonville
P0300 Random Misfire...HELP!
2003 g35 coupe with turbonetics kit installed about 6 years ago...been running great until about 3 months ago, i started getting a misfire problem. Only code it shows is p0300 (random misfire), it will not show any other codes. Car is tuned with UTEC.
Idle is rough, driving is really rough.
Diagnostic scanner showed car was running rich. CEL blinks when driving.
Took it to a shop to diagnose and they couldnt tell me what was wrong...but the guy said it sounds rhythmic like its the same cylinder missing every time.
Things i've replaced or tried:
-New spark plugs, NGK one step colder....just like what was in there.
-New walbro fuel pump
-Sprayed carb cleaner on all vacuum lines and leak prone spots on the motor, idle didnt change
-Retighted all intercooler and intake piping.
-Tested coils by idling car and unplugging each coil one at a time...idle dipped on each cylinder but cylinder 2.
-Swapped coils and plugs from other cylinders to cylinder 2, still no spark
To rule out the coil i swapped coil from cylinder 1 and tested again to see if idle would dip...sure enough cylinder 2 didnt change idle when unplugged...but cylinder 1 did.
So i take cylinder 1 plug and swap it with cylinder 2, still no change in cylinder 2.
To make sure i am getting spark or not on cyl 2 i pull the coil and plug from the motor and reinstall the plug in the coil outside of the motor while coil is still plugged in and had my fiance turn the car over while the plugs threads were grounded to the strut bolt. No spark. To check this method i pull cyl 4 coil and plug and ground the plugs threads to the same bolt on the motor...i get spark just fine. I do the same on cylinder 1 just to make sure and sure enough cyl 1 has spark.
I can't get spark on cyl 2 to save my life....no matter what plug or coil i swap to it. Any ideas?
Idle is rough, driving is really rough.
Diagnostic scanner showed car was running rich. CEL blinks when driving.
Took it to a shop to diagnose and they couldnt tell me what was wrong...but the guy said it sounds rhythmic like its the same cylinder missing every time.
Things i've replaced or tried:
-New spark plugs, NGK one step colder....just like what was in there.
-New walbro fuel pump
-Sprayed carb cleaner on all vacuum lines and leak prone spots on the motor, idle didnt change
-Retighted all intercooler and intake piping.
-Tested coils by idling car and unplugging each coil one at a time...idle dipped on each cylinder but cylinder 2.
-Swapped coils and plugs from other cylinders to cylinder 2, still no spark
To rule out the coil i swapped coil from cylinder 1 and tested again to see if idle would dip...sure enough cylinder 2 didnt change idle when unplugged...but cylinder 1 did.
So i take cylinder 1 plug and swap it with cylinder 2, still no change in cylinder 2.
To make sure i am getting spark or not on cyl 2 i pull the coil and plug from the motor and reinstall the plug in the coil outside of the motor while coil is still plugged in and had my fiance turn the car over while the plugs threads were grounded to the strut bolt. No spark. To check this method i pull cyl 4 coil and plug and ground the plugs threads to the same bolt on the motor...i get spark just fine. I do the same on cylinder 1 just to make sure and sure enough cyl 1 has spark.
I can't get spark on cyl 2 to save my life....no matter what plug or coil i swap to it. Any ideas?
Last edited by BoostinJaxG; Mar 28, 2014 at 01:21 PM.
Thread Starter
Registered User
Joined: Feb 2014
Posts: 19
Likes: 0
From: Jacksonville
Fuel injector could be the result of the misfire as well, but it doesnt explain why there is NO SPARK on cyl 2. I KNOW i have a spark issue on that cylinder, just dont know why.
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