Engine stumbling!! Self test codes HELP PLEASE!!
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Senior User
Joined: Feb 2005
Posts: 200
Likes: 1
From: Chester County PA
Engine stumbling!! Self test codes HELP PLEASE!!
My truck is not runing right at all. It's terrible, it stubles and studders once it warms up. It's sounds like it's missing. Also when I relly get on the gas it backfires in the exhaust. It's a 91 F150 302, 5spd, dual exhaust o2 bung in h-pipe. It's been running fine for a while (no problems), and then it suddenly went down hill the other day.
I got the following codes (Key On Engine ON):
29c
52c
92c
(Key on engine off):
31c
32c
33c
I know that code 29c is because I put in a 9inch rear instead of my 8.8 but that shouldnt be causing the problem.
Could the oxygen sensor be bad. It only has 20,000 miles on it.
I checked ACT, ECT & MAP sensors. I also swapped out the ecu for a similar one, no changes. I also checked the fuel filter.
It's eating gas like crazy.
Any help is greatly appreciated !! Thanks -Mike
I got the following codes (Key On Engine ON):
29c
52c
92c
(Key on engine off):
31c
32c
33c
I know that code 29c is because I put in a 9inch rear instead of my 8.8 but that shouldnt be causing the problem.
Could the oxygen sensor be bad. It only has 20,000 miles on it.
I checked ACT, ECT & MAP sensors. I also swapped out the ecu for a similar one, no changes. I also checked the fuel filter.
It's eating gas like crazy.
Any help is greatly appreciated !! Thanks -Mike
Last edited by fordman16b; Feb 26, 2007 at 06:30 PM.
Posting Guru
Joined: Jun 2004
Posts: 1,781
Likes: 1
From: Central NY
You can't get a 33 with KOEO.
It sounds like you have some vacuum leaks to hunt down. EGR valve & related might be a good place to start.
KOER (Engine Running) Was it warmed up when you did this? IF it was then it you'll need to resolve vacuum leaks before you troubleshoot the Rich problem imo.
Check your fuel pressures if you can.
It sounds like you have some vacuum leaks to hunt down. EGR valve & related might be a good place to start.
KOER (Engine Running) Was it warmed up when you did this? IF it was then it you'll need to resolve vacuum leaks before you troubleshoot the Rich problem imo.
Check your fuel pressures if you can.
Senior User
Joined: Oct 2003
Posts: 351
Likes: 1
From: Sullivan, IL USA
I would say it could be timing chain slack. Disconnect timing spout so computer can't control timing and if you have timing light, reset timing (it will say under hood factory timing). Run the engine for a while to warm up before setting timing. After it is set take it for a drive with the spout still disconnected. Then put spout back in, take for a drive. If it runs better without spout after timing reset, the computer is trying to compensate for timing change. This is how eliminated electrical vs mechanical. And it was my timing chain slack. Not to say there isn't alot of other things that could cause your problem, but this is a quick easy check.
Thread Starter
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Senior User
Joined: Feb 2005
Posts: 200
Likes: 1
From: Chester County PA
The engine only has 20,000 miles on it. I checked the timing when the engine was warm with the pip out, and the timing was dead steady.
Still trying to figure this out. Thanks for the help so far.
Still trying to figure this out. Thanks for the help so far.
New User
Joined: Jan 2007
Posts: 5
Likes: 0
I have a 95 f150 302 4x4ex cab w/149,000m. Just changed plugs, wires,rotor, cap, fuel filter and still get the same as the rest-sshudder after it warms up-like it is loading up. My buddy is putting it on a scope to check codes, but his first guess is mass air flow valve/sensor. He says from what I told him it sounds as if it is getting to much gas! Will let ya know.
I posted this on an old post that I didn't see the date on so sorry if it is repetitive
I posted this on an old post that I didn't see the date on so sorry if it is repetitive
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striker_wvu
1987 - 1996 F150 & Larger F-Series Trucks
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May 20, 2008 08:35 AM
