2002 Ford F-150 Cylinder 5 Misfire

Tiny
TJ41181
  • MEMBER
  • 2002 FORD F-150
  • V8
  • 2WD
  • AUTOMATIC
  • 75,000 MILES
It has been diagnosed that cylinder 5 has a PSI of only 80. What is the normal PSI? It has been recommended that the engine be rebuilt. Is this the correct diagnosis or is there an alternative? We have changed all spark plugs and coils with boots. The truck runs very good but the check engine light still comes on.
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Saturday, December 29th, 2007 AT 9:05 PM

9 Replies

Tiny
BLACKOP555
  • MECHANIC
  • 10,371 POSTS
Should be no more then 25% less then the highest cylinder, there is no set compression for one clinder.
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Saturday, December 29th, 2007 AT 10:06 PM
Tiny
TUBASOUSA
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  • 5 POSTS
Go to autozone or somewhere like that and have them scan the code and put that code here on the site so I can see it. You shouldn't have to rebuild your engine at only 75k miles. A normal rebuild should be done at well over three time that amount. This is most definitely a bad diagnosis. Try to listen for any leaks or hisses coming from the area where the head meets the block. If you can hear a hissing sound coming from this area. Then you may have a blown head gasket. Also try feeling near this area to see if you can feel air leaking out. A blown head gasket will not require a rebuild, but only a removal of the head. The check engine light may be coming on due to some other unrelated problem but im not sure untill I can see the code. Please post it on here, thank you.
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Monday, December 31st, 2007 AT 12:50 AM
Tiny
TJ41181
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The codes shown on the printout are P0316 and P0305. Thank you for your help.
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Wednesday, January 2nd, 2008 AT 4:39 PM
Tiny
BLACKOP555
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P0305 is a cylinder five missfire. And P0316 is engine missfire detected on start up, this comes from the P0305 missfire more then likely.

I would suggest spark plugs, spark plug wires, (distributor cap and rotor if equipped on vehicle) Otherwise, check the coils/coil packs

if this is not the problem check the compression on the cylinder and if that is up to specs you should have your fuel injector checked out.
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Wednesday, January 2nd, 2008 AT 7:40 PM
Tiny
TJ41181
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Thanks to all of you who have responded. When the check engine light first came on the truck was missing and running very rough. I changed all the spark plugs, replaced all the boots on the coils, replaced the entire coil on cylinder 5 and the fuel filter. The truck runs great now, no missing. However, the check engine light continues to come on and the codes previously stated continue to show as the reason. It is very hard to understand what could be wrong when it runs so well. If you have any other suggestions I would greatly appreciate it. Thanks again for your help. :)
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Thursday, January 3rd, 2008 AT 7:59 AM
Tiny
BLACKOP555
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You may have a faulty computer, did you try resetting the code? I wouldnt worry about the computer, if it runs good then thers nothing to worry about.
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Thursday, January 3rd, 2008 AT 12:24 PM
Tiny
TJ41181
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How do you reset the computer? I unplug the battery and the light goes off but after driving the truck for some miles, the light comes back on. Are you saying that the computer is keeping these codes stored?
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Thursday, January 3rd, 2008 AT 2:41 PM
Tiny
BLACKOP555
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Remove the negative battery cable for 1 minutes, the computer is what stores the codes, and if it keeps missreading a cylinder5 missfire when there isnt one then it probably has a faulty sensor.
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Thursday, January 3rd, 2008 AT 6:43 PM
Tiny
TJ41181
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Thank you for all your help.
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Thursday, January 3rd, 2008 AT 8:37 PM

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