2004 gxp misfires - Page 2 - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


Bonneville GXP/ Northstar Powered Cars Discuss your Bonneville GXP and/or any other Northstar powered Olds or Cadillac... Including the 3.5L Twin Cam V6 (Short Star ) 4.0L and 4.6L Northstar V8's. Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.

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Old 07-18-2011, 01:56 PM   #11
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Running lean with random misfires may be indications of a vacuum leak. Get some carb cleaner and spray all vacuum connections. Changes in idle speed when spraying indicates a leak.

The other possibility to be considered is low fuel pressure. Check fuel pressure at the rail. A failing fuel pump can cause randon misfire.
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Old 07-18-2011, 07:31 PM   #12
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misfire is cylinder 6, oh how I hate my fracking car......

facing the engine isn't 6 in the back and third from the left or second from the right? someone tell me so I can go change this plug....

thanks
rich
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Old 07-18-2011, 07:33 PM   #13
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Cylinder 1 is front passenger side, 8 is back drivers side.
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Old 07-18-2011, 07:44 PM   #14
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Try swapping injectors around?
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Old 07-18-2011, 07:44 PM   #15
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you are so not my friend dan...... i'll let you all know if this solves the problem, of not I guess its coil pack time....
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Old 07-18-2011, 07:45 PM   #16
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I'll put my money on a bad coil.
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Old 07-19-2011, 07:59 AM   #17
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i would think that ign faults would give you a rich indication not lean
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Old 07-19-2011, 10:10 PM   #18
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well since it didnt rain tonight, I crawled up on top of the engine and wrenched out plug number 6....

threads had a good amount of oil on them and the plug looked pretty burned out,,, only 16000 miles old too, however, its still missing, and that leads me to the coil.....
ordered one tonight,,,,,, should take 3 to 5 business days to arrive at my door, and ohh goody I get to have all that fun I had tonight in 95 degree heat all over again.... yayyyyy

cause for oil on plug?? not used to seeing that...

also anyone have a good diagram with arrows so I know which hoses are vacuum so I can test for vacuum leak? sorry to be ignorant, but vacuum hoses are not my cup of tea......

most of my friends would pay to have that plug changed tonight, me I just jump up and go to town...
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Old 07-20-2011, 03:49 PM   #19
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wish i saw this thread earlier, i had similar issue with my GXP it was a bad coil
as Dan stated before, code P0300 is a pig. Doesnt give you much to play with unless you get which cylinder its misfiring.
I put my money on a bad coil, I guess we have to wait and see.

Any pictures of your engine mounts? Mine just hit 64k miles and shes going into service soon id like to see what they look like comparing to mine. Also how can i know if they are bad? its under warranty id like to know if they are bad so they can fix them.

Now i'll stop talking and wish you good luck.


Sammy K.
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Old 07-20-2011, 09:41 PM   #20
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Sam,
the fron mount on the 2004 is a bitch... it'* basically a piece of rubber with a stud sticking out of the middle on both ends.... My engine was bouncing back and forth violently is how I knew the front one went bad.... I put it in drive and the black mark we drew on the engine cover moved 16 inches when I accelerated with the brakes engaged. Was a pretty clear sign the front one was bad... Sub frame has to come off to change it, so I paid to have it changed.
Rear mount is behind the fire wall and again the subfram has to go... I thought by left over engine bounce was still a mount, turned out it was still good....
My misfire is causing my idle bounce,,,,, I have a coil intransit, it will arrive on Friday......

anyone have any comment as to why I might have had a non normal amount of oil on the threads of the plug I removed?
oh and I stepped on and cracked my engine cover while I was working on it yesterday.... Short of a new one, anyone know where I can get a used one??/ No salvage yards in Ohio have seen one...
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