2004 gxp misfires
#1
Member
Posts like a V-Tak
Thread Starter
Join Date: Dec 2010
Posts: 38
Likes: 0
Received 0 Likes
on
0 Posts
2004 gxp misfires
guys my 04 feels like its just falling apart...
three weeks ago I replaced the front engine mount because I had engine movement and we were pretty sure that was the cause... oh and the mount was toast..torn rubber at the stud.
after the mount was replaced it was still bouncing, and started running a little hard at idle....
coded maf sensor, multiple misfires, front o2 sensor, and two fuel codes that I forget...oh and a cruise control code.... no body codes....
oh and numerous times cruise control has been on at 75 mph, the SSS pops up and then low traction and cruise shuts off...
cleaned the maf, and cleared the history, oh and replaced rear engine mount too...
still have the misfires, maf code is gone, fuel codes gone, o2 code still there.
thoughts? coil? injector? best trouble shoot option?
thanks,
Rich
three weeks ago I replaced the front engine mount because I had engine movement and we were pretty sure that was the cause... oh and the mount was toast..torn rubber at the stud.
after the mount was replaced it was still bouncing, and started running a little hard at idle....
coded maf sensor, multiple misfires, front o2 sensor, and two fuel codes that I forget...oh and a cruise control code.... no body codes....
oh and numerous times cruise control has been on at 75 mph, the SSS pops up and then low traction and cruise shuts off...
cleaned the maf, and cleared the history, oh and replaced rear engine mount too...
still have the misfires, maf code is gone, fuel codes gone, o2 code still there.
thoughts? coil? injector? best trouble shoot option?
thanks,
Rich
#2
Senior Member
True Car Nut
is it the lean o2 code? specific codes would help. i think i remember someone having issues with the gxps running too lean, maybe a search on here for the specific code
#4
Member
Posts like a V-Tak
Join Date: May 2011
Location: Salisbury, NC
Posts: 37
Likes: 0
Received 0 Likes
on
0 Posts
If you have a way to get a scan tool hooked up to it. Or take it to your local Auto Zone and they can at least hook up a code reader. Try to determine exactly what cylinder is being affected if indeed it is a misfire. It'* possible it could be something else causing the root of your problem. If you are capable of diagnosing with a flow chart I might can help and send you some info. just let me know
#5
Member
Posts like a V-Tak
Thread Starter
Join Date: Dec 2010
Posts: 38
Likes: 0
Received 0 Likes
on
0 Posts
yes o2 lean code....
please limit replies to knowledge of the LD8 engine..(it has no spark plug wires)
as to getting it coded, its only reading misc misfire codes, not telling us which one
plugs new 20,000 miles ago, unlikely to be plug....most likely a coil or injector,,,
anyone know of a scanner that can give me the definate misfire cylinger? We have the big obdII but it isnt isolating it....
checked plugs for being loose, and they are all in and snug, god I hate the back half of doing that......
please limit replies to knowledge of the LD8 engine..(it has no spark plug wires)
as to getting it coded, its only reading misc misfire codes, not telling us which one
plugs new 20,000 miles ago, unlikely to be plug....most likely a coil or injector,,,
anyone know of a scanner that can give me the definate misfire cylinger? We have the big obdII but it isnt isolating it....
checked plugs for being loose, and they are all in and snug, god I hate the back half of doing that......
#6
Senior Member
True Car Nut
there are separate codes for random misfire and individual cyl. misfire. if your getting the random then its all of them.
so that being said it may be your fuel pressure may be starting to decline do you have a gauge?
here is the other thread with some more possibilities; https://www.gmforum.com/bonneville-gxp-northstar-powered-cars-107/p0171-p0174-04-gxp-299148/page2/
so that being said it may be your fuel pressure may be starting to decline do you have a gauge?
here is the other thread with some more possibilities; https://www.gmforum.com/bonneville-gxp-northstar-powered-cars-107/p0171-p0174-04-gxp-299148/page2/
#7
Retired Senior Admin
Expert Gearhead
Join Date: May 2006
Location: Sheboygan Wisconsin
Posts: 29,661
Likes: 0
Received 28 Likes
on
24 Posts
This engine has coil overs, so no plug wires. The P0300 code is of little use, I hate that code. You may have to have it scanned a few times over several days and you should get a P030x code, like P0303. Once you have that code you can replace that coil. However, if you have a good eye, you can pull the plugs and inspect them real close. You may see a slight difference in one plug, should be a bit darker then the rest. That one will be your weak spark. The lean code could be a dirty O2 sensor. Running with a misfire will run rich and plug up the O2 sensor causing it to read lean.
#8
Member
Posts like a V-Tak
Thread Starter
Join Date: Dec 2010
Posts: 38
Likes: 0
Received 0 Likes
on
0 Posts
thanks jw, and dan...
yeah its a mess.... we've scanned it as many as 5 days in a row and no isolation code to tell em which cylinder... driving us nuts...
I cant replace the two O2 sensors until I fix this issue...
it'* also causing an engine bounce,(not mounts just replaced those)
could the fuel pressure regulator cause any of this? it'* inexpensive and in a suprisingly easy to get to location to change???
no vaccuum issues, but how bout PCV? can that cause any of this?
yeah its a mess.... we've scanned it as many as 5 days in a row and no isolation code to tell em which cylinder... driving us nuts...
I cant replace the two O2 sensors until I fix this issue...
it'* also causing an engine bounce,(not mounts just replaced those)
could the fuel pressure regulator cause any of this? it'* inexpensive and in a suprisingly easy to get to location to change???
no vaccuum issues, but how bout PCV? can that cause any of this?