Help One bad spark plug
#1
Registered Member
Thread Starter
One bad spark plug
Hi, I just purchased my 2008 G37 and when I test drove it, it felt great, no issues. After having it delivered across the state and driving it for less than 2 hours, I had the service engine light come on. The next day, it started blinking. I replaced the spark plugs last night and found just one to be darker. Drove it this morning and it came on intermittently and then started blinking. I cleaned the throttle body and MAF sensor. It starts blinking when it goes into higher Rev and then when turns off when I cruise but still comes on here and there. I have an appointment at a shop on Monday, which I scheduled for an inspection before all this happened. What tests are the best way to figure out the source of the problem? TIA
#2
Super Moderator
Is the plug on the end a different brand? Same heat range?
#3
Registered Member
Thread Starter
Wow my eyes didn't even catch that 🤣. So it is a different brand - Bosche R6 which have a heat range of 9 and the rest are Denso with heat range 8. So someone did change this one out for some reason and I don't have info as to why.
#5
Super Moderator
I think the failure at higher revs indicates that there is a misfire, which may be why one plug was targeted. The plugs themselves look fairly standard.
I think he needs an OBD2 reader to see what codes are being thrown. Maybe a bad coil (code will indicate which one)? Although, the coils either work or not work as I haven't seen anyone post about intermittent coil failures.
#6
Registered Member
Thread Starter
Based on the initial post, it sounds like @Simsimmah already replaced the plugs. Wondering thought why there was the one oddball in the set he replaced as it appears someone tried to use a new plug to fix another issue.
I think the failure at higher revs indicates that there is a misfire, which may be why one plug was targeted. The plugs themselves look fairly standard.
I think he needs an OBD2 reader to see what codes are being thrown. Maybe a bad coil (code will indicate which one)? Although, the coils either work or not work as I haven't seen anyone post about intermittent coil failures.
I think the failure at higher revs indicates that there is a misfire, which may be why one plug was targeted. The plugs themselves look fairly standard.
I think he needs an OBD2 reader to see what codes are being thrown. Maybe a bad coil (code will indicate which one)? Although, the coils either work or not work as I haven't seen anyone post about intermittent coil failures.
#7
Super Moderator
P0133 is O2 sensor-1 (A/F Sensor) Bank-1 (passenger side sensor - located before or in front of the cats) correct? That failure will likely cause the other code to be thrown. No modification to the factory cats?
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#8
Registered Member
Thread Starter
It's got an after market exhaust (Manzo) but not sure how far upstream the mod starts. I'll get that info when I get the inspection tomorrow. I got it scanned again since I hadn't yet after plug replacement. Now the primary code is P0300 - too many random cylinder misfires and suggests replacing MAF sensor. Additional codes are P0420 (CAT system bank 1), P0456 EVAP system very small leak, P0133 AFR sensor 1.
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08-01-2022 08:04 PM