Diagonosing engine trouble codes
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Mountain Pass
Joined: Apr 2009
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Diagonosing engine trouble codes
'02 F350 with V10. I recently bought this truck and had to get an emissions test. The emissions testing facility said the truck needed a new gas cap because the old one wasn't holding adequate pressure. So, I installed a new cap, and it passed the emissions test.
Several days and miles later, the check engine light came on. Some time after, on the first start of the day, the truck wouldn't idle without continually giving it gas, but after a few miles, it idled fine.
I had Auto Zone check the codes, and their scanner indicated a P0301 and a P0171 code. The P0301 is cylinder misfire in no. 1, which could be caused by ignition system fault (spark plugs, ignition wires, or coil), vacuum leak, injector fault, or high or low pressure.
The P0171 code indicates a fuel trim bank one condition. The computer has recognized a rich or lean condition on one engine bank only. Possible causes include fuel pressure or MAF sensor, or oxygen sensor, ignition misfire, or fuel injector problem.
The truck seems to run fine. I haven't noticed any misfire. I was planning on changing the plugs, so I guess that's the first place to start. Would a defective gas cap seal cause any of these engine codes?
Any other suggestions on where to look?
Thanks.
Several days and miles later, the check engine light came on. Some time after, on the first start of the day, the truck wouldn't idle without continually giving it gas, but after a few miles, it idled fine.
I had Auto Zone check the codes, and their scanner indicated a P0301 and a P0171 code. The P0301 is cylinder misfire in no. 1, which could be caused by ignition system fault (spark plugs, ignition wires, or coil), vacuum leak, injector fault, or high or low pressure.
The P0171 code indicates a fuel trim bank one condition. The computer has recognized a rich or lean condition on one engine bank only. Possible causes include fuel pressure or MAF sensor, or oxygen sensor, ignition misfire, or fuel injector problem.
The truck seems to run fine. I haven't noticed any misfire. I was planning on changing the plugs, so I guess that's the first place to start. Would a defective gas cap seal cause any of these engine codes?
Any other suggestions on where to look?
Thanks.
Posting Guru
Joined: Apr 2003
Posts: 1,089
Likes: 1
From: Michigan
Almost always on the V10 a misfire is caused by a primary ignition source (COP or COP boot). Change your plugs and inspect all COP's and boots. Use dielectric grease when reinstalling. If the misfire is still there on #1, you can switch the COP's to see if the fault follows. This way you will know if it is the COP that is bad.
P0171 is bank one lean condition. Bank one on Fords is the passenger side. Check for any vacuum leaks ect... Also, it is a good idea to clean the MAF. You need to take out your air cleaner and you will see the MAF element in there. Don't touch it!! CRC make some good MAF cleaner. Get it at your local auto parts store.
None of these issues would be caused by a bad gas cap.
P0171 is bank one lean condition. Bank one on Fords is the passenger side. Check for any vacuum leaks ect... Also, it is a good idea to clean the MAF. You need to take out your air cleaner and you will see the MAF element in there. Don't touch it!! CRC make some good MAF cleaner. Get it at your local auto parts store.
None of these issues would be caused by a bad gas cap.
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