Misfire and check engine light blinking in truck
09-09-2010, 04:09 PM
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Misfire and check engine light blinking in truck
OK I have posted before and fixed a few problems. Now my 1996 Ford F-150 with a 4.9 300 straight 6 is throwing a misfire code and system to lean code. I just changed the spark plug on the fifth cylinder (the one that is misfiring). The old plug had a little bit of buildup of black stuff but it wasn't oil. SO I changed it and it was OK. I didn't reset the codes. I wanted it to reset itself. I got on the main road and punched it and got it to 60 then had to turn around. Once I started off again it gave me a little hard time getting up to speed and then I punched it and it got to 45-55 then the Check Engine Light Started To Blink. It was still on then it blinked about ten times then it stayed on again. Whats wrong with it now. It seems every time something is fixed it messes up again. I hope I didn't mess something up.
09-09-2010, 05:01 PM
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OK I have posted before and fixed a few problems. Now my 1996 Ford F-150 with a 4.9 300 straight 6 is throwing a misfire code and system to lean code. I just changed the spark plug on the fifth cylinder (the one that is misfiring). The old plug had a little bit of buildup of black stuff but it wasn't oil. SO I changed it and it was OK. I didn't reset the codes. I wanted it to reset itself. I got on the main road and punched it and got it to 60 then had to turn around. Once I started off again it gave me a little hard time getting up to speed and then I punched it and it got to 45-55 then the Check Engine Light Started To Blink. It was still on then it blinked about ten times then it stayed on again. Whats wrong with it now. It seems every time something is fixed it messes up again. I hope I didn't mess something up.
09-12-2010, 10:24 AM
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The wires are the oldest out of them all i just changed the caps rotor and spark plugs about a month ago. The spark plug I change had black gunk on it but it wasnt oil. The code still reads the same even after I changed the spark plug and it says system to lean bank one and system to lean bank 2 and misfire on cylinder 5
09-13-2010, 10:56 AM
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SO you think that the wiring to the fuel injector might be messed up and not the wiring to the plug. I can check but i believe its getting gas because the spark plug has gas on it.
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09-13-2010, 01:13 PM
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Baring wires, slop in the distributor shaft (out of tolerance), comes to mind. Or a weakened condition of the coil, with the #5 presenting the path of most resistance.
How many miles on the o2's? More than 60K, replace them especially if MPG is important it you.
If your engine is MAF, you have sequential fuel injection, providing individual injector modulation. Clean the MAF w/ MAF cleaner or Electronic contact cleaner. You don't have a CAI mod do you?
Last edited by ymeski56; 09-13-2010 at 03:23 PM.