2002 5.4 ltr Triton mis-fire at idle
09-13-2015, 12:05 AM
#1
2002 5.4 ltr Triton mis-fire at idle
I have a misfire at idle and NO CHECK ENGINE LIGHT. I have sprayed carb cleaner around top of engine when it was cold to see if I had a vacuum leak and did not notice any difference in the rpm's. I have replaced all spark plugs and gaped them at .045 as my Chilton manual states. I am getting frustrated as there has been NO check engine light. Looking for suggestions or ideas on what to check next. I rcvd the following from lewissa81 which I found interesting and thanked him for his info.
lewissa81
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It could be any number of things. Since you changed the plugs, next I would run a couple tanks with Techron and clean the throttle body/ mass airflow sensor. If you have a scanner, I would monitor the O2 sensors and fuel trims to see if you're running rich or lean, and if the O2's are switching. If you're running rich, it could be a faulty coil or injector. If your running lean, you could have a clogged/faulty injector, or a vacuum leak you just couldn't find.
Of course with both rich and lean conditions, you could have one or more faulty O2's. They can get lazy over time, misreport data, and can just fail. Monitoring them and the fuel trims will also help you determine whether you should focus on one bank, or if both are effected. Good luck. Those misfires can be a pain to find. I'm sure there are other things that I'm forgetting too.
lewissa81
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Join Date: Feb 2014
Location: Birmingham, Alabama
Posts: 965
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Thanked 86 Times in 85 Posts
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It could be any number of things. Since you changed the plugs, next I would run a couple tanks with Techron and clean the throttle body/ mass airflow sensor. If you have a scanner, I would monitor the O2 sensors and fuel trims to see if you're running rich or lean, and if the O2's are switching. If you're running rich, it could be a faulty coil or injector. If your running lean, you could have a clogged/faulty injector, or a vacuum leak you just couldn't find.
Of course with both rich and lean conditions, you could have one or more faulty O2's. They can get lazy over time, misreport data, and can just fail. Monitoring them and the fuel trims will also help you determine whether you should focus on one bank, or if both are effected. Good luck. Those misfires can be a pain to find. I'm sure there are other things that I'm forgetting too.
Last edited by ndoutdrs; 09-13-2015 at 12:08 AM. Reason: sharing info
09-13-2015, 08:18 AM
#2
Mark
iTrader: (1)
mileage ?
09-13-2015, 09:03 AM
#4
Mark
iTrader: (1)
Thats what i was getting at too... replace the COP's
09-13-2015, 09:49 AM
#5
2002 5.4 ltr Triton mis-fire at idle
Just a thought, but if your gas tank isn't over half full (or maybe quarter?) the code for misfires will not be set.
I would fill it up, reset my computer, and drive it to see if it will set a code.
I would fill it up, reset my computer, and drive it to see if it will set a code.
09-13-2015, 12:04 PM
#7
It happens whether it's full or between 1/4 and full. Notice it at stop lights.
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09-23-2015, 08:16 PM
#8
09-23-2015, 08:22 PM
#9
