Missing at idle
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New User
Joined: Jul 2012
Posts: 5
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From: Colorado
Missing at idle
I rebuilt a 1997 F250 5.4L engine and transmission recently and when i started it has a miss. I drove it and it misses all the time. I totally rebuilt the engine, new pistons, rebuilt heads, new spark plugs, new ign coils, new injectors, etc. I am thinking that the timing could be off but I did follow the details on lining up the dots with chain.
Does anyone have any suggestions before me taking the front of the engine off again!
Does anyone have any suggestions before me taking the front of the engine off again!
Thread Starter
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New User
Joined: Jul 2012
Posts: 5
Likes: 0
From: Colorado
I cannot tell which cylinder or cylinders are missing because it is not throwing a code. Also it idles ok but as soon as you press on the gas in gear it starts to miss. Also while you are driving it still has a miss.
Lead Driver
Joined: Sep 2006
Posts: 7,907
Likes: 143
It's not making any sense.
Misfires are detected as slow crank rotation times by the crank sensor every time a cylinder fires.
If any cylinder does not rotate the crank with combustion pressure that compares with a table in software it's deemed a misfire.
No codes is no misfires.
The causes of misfires are coils, plugs, loss of fuel, ignition, cylinder mechanical issues and the PCM plus any wire harness or electrical power issue.
You have something else going on.
You need someone that knows what to look for to sort your issue out.
Good luck.
Misfires are detected as slow crank rotation times by the crank sensor every time a cylinder fires.
If any cylinder does not rotate the crank with combustion pressure that compares with a table in software it's deemed a misfire.
No codes is no misfires.
The causes of misfires are coils, plugs, loss of fuel, ignition, cylinder mechanical issues and the PCM plus any wire harness or electrical power issue.
You have something else going on.
You need someone that knows what to look for to sort your issue out.
Good luck.
Senior User
Joined: Jul 2004
Posts: 247
Likes: 3
From: Illinois
finally threw a code after a week
it was a bad coil
I'd just double check the plugs and coils and everything is good
I'd look real close at the passenger side for a little coolant leak, that's pretty common.
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