fouling #1 plug
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Teching In
Joined: May 2012
Posts: 26
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From: Bardstown KY
fouling #1 plug I have a 2009 G8 6.0
Ok so about a week ago I noticed the car doing the huckle buck when driving in OD at low RPM. It felt like the convertor was locking up to soon to give ya an idea. The car is cammed and stalled as well which made me believe it was part of the issue.
I drove it for past two weeks and the huckle buck became to feel more like a miss. I got to doing some of the obvious diagnosing.
Pulled the plugs and #1 was black, all others a nice tan
Changed plugs and I had an extra coil pack laying around and did a quick swap. I drove down the road and the same thing. Fouled plug
I swapped coils/wires from 1-3 to make sure it wasn't a bad coil I had. Same thing
Next I pulled the injector and bench tested it and cleaned it up, put it back together, same thing. Fouled another plug
Took it all apart again and swapped injectors, which I should have done first time it was apart, same outcome. #1 fouled another plug
I did a compression test and 1-3-5-7 all were at 180.
My buddy is service manager at chevy dealer so we hooked it up to a scanner and drove around and it showed no misfires at all.
Pulled the valve cover today to verify there wasn't an obvious valve train issue like broken rocker/spring etc. All is good.
Plug pic attached.
Any help would be appreciated.
Ok so about a week ago I noticed the car doing the huckle buck when driving in OD at low RPM. It felt like the convertor was locking up to soon to give ya an idea. The car is cammed and stalled as well which made me believe it was part of the issue.
I drove it for past two weeks and the huckle buck became to feel more like a miss. I got to doing some of the obvious diagnosing.
Pulled the plugs and #1 was black, all others a nice tan
Changed plugs and I had an extra coil pack laying around and did a quick swap. I drove down the road and the same thing. Fouled plug
I swapped coils/wires from 1-3 to make sure it wasn't a bad coil I had. Same thing
Next I pulled the injector and bench tested it and cleaned it up, put it back together, same thing. Fouled another plug
Took it all apart again and swapped injectors, which I should have done first time it was apart, same outcome. #1 fouled another plug
I did a compression test and 1-3-5-7 all were at 180.
My buddy is service manager at chevy dealer so we hooked it up to a scanner and drove around and it showed no misfires at all.
Pulled the valve cover today to verify there wasn't an obvious valve train issue like broken rocker/spring etc. All is good.
Plug pic attached.
Any help would be appreciated.
Can't see clearly in the picture but the plug seems fouled with sooth, it's not wet.
So, this means a rich condition causing loss of power on that cylinder, but there is combustion. It's not a dead cylinder or the plug would be wet fouled.
Unplug the injector and the PCM, test the injector circuit to check ohms from PCM to injector, it should be less than 0.5. Check if the wire is shorted to ground.
Plug the PCM back and let the engine idle, with the injector unplugged use a test light to see if the pulses are what they should be, compare to other cylinders.
If those test check OK, then the PCM may be bad
So, this means a rich condition causing loss of power on that cylinder, but there is combustion. It's not a dead cylinder or the plug would be wet fouled.
Unplug the injector and the PCM, test the injector circuit to check ohms from PCM to injector, it should be less than 0.5. Check if the wire is shorted to ground.
Plug the PCM back and let the engine idle, with the injector unplugged use a test light to see if the pulses are what they should be, compare to other cylinders.
If those test check OK, then the PCM may be bad
Soot is HC residue and HC comes up at either end of
the mixture range. This could be a lean misfire from an
injector that shoots leaner than the rest (but still does
deliver a shot, that fires poorly). Injectors at end-of-rail
are the first to silt up. You could swap-test that theory.
Another possibility is coils / wires making the spark snuff
out under some load conditions (more cylinder pressure
needs more spark voltage and spark may decide to go
elsewhere).
the mixture range. This could be a lean misfire from an
injector that shoots leaner than the rest (but still does
deliver a shot, that fires poorly). Injectors at end-of-rail
are the first to silt up. You could swap-test that theory.
Another possibility is coils / wires making the spark snuff
out under some load conditions (more cylinder pressure
needs more spark voltage and spark may decide to go
elsewhere).
I don't think a compression test would rule out a bad intake side lifter on #1 cylinder. This would be unbelievably odd, but you seem to have ruled out all of the usual suspects.
