2002 GMC Yukon Denali - 6.0L Misfire FIXED

[autoxperts]

vehicle came in with a misfire.

misfire is only on bank two plugs have been changed coil packs check good,wires are new scanner gave codes dtc 300,when idling when u drive it throws it will not hardly go like converter is block. would stop up converter, cause misfire.

any help would be appreciated

[steven kiser]

check 02 on that bank

[autoxperts]

they check fine exhaust has bad odor. 4& 6 are the worst. injectors are pluseing good

[steven kiser]

if it's a skip right off the bat i would check compression. possible bad intake gasket. i had one that would run fine when 02 was unplugged. found the sensor was forcing rich.

[autoxperts]

compression is 150 and already check for intake leak

[steven kiser]

fuel pressure regulator leaking?

[autoxperts]

no already check that too

[sbebenelli]

Have you checked the back pressure?

[autoxperts]

unplug o2 sensors did not make any difference; exhaust pressure isn't that good.

[steven kiser]

i've seen banks killed by the pcm. check that banks 02 readings. if they're flat lined or maxed the pcm will try to adjust that bank to make it right. watch the readings while un plugging 02. pcm may not be getting a signal and killing that bank. you may have a bad pcm or broken wire. unplug the map. this should force it into limp. if it doesn't then the pcm is probably bad. if it does you may have a broken wire, or a bad pcm.

[autoxperts]

passenger side cat was stop up it fix problem runs great

[steven kiser]

Glad you got it fixed. I just need a bit of clarification here. When you posted back pressure wasn't that good what exactly did you mean. If the pressure was tested correctly the plugged cat would have stood out. Again, i'm always glad to hear about a fix.