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F-150 misfire

--weezl--

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Hey, my dad's got a 96 f-150, with a constant but varing intensity misfire that he's been harping on me to figure out.

it starting occasionally, and over the past month, has become constant, sometimes it is very minor, and can barely be noticed, other times the whole truck shakes violently.

the truck is a has a 5.0 5speed reg cab long box, it's been well maintained over it's 230,000 km (I think that's right) the exhaust pipe (before this, not sure about now) was SPOTLESS, and i mean like looked like galvanized steel inside, not a spec of carbon or any other contaminant. it was pinging rather bad for a while, getting worse, so a large tune up was done, plugs, wires, cap, rotor, was done about 2-3 months before this happened, new belt, new idler pulley, new shoes, pads, rotors, drums, and front bearings were done about 2 weeks before this (him and I did all the work) there is NO CEL, but don't have a code reader to check to make sure no codes. the truck is pretty much all stock, no major modifications.

so far I have had him check inside the cap, he said it was "a little crusty, but not bad" not sure exactly what he's meaning... he suspects compression issue, but goes on to mention "miss is the same cylinder, can be worse or better during a trip" which leads me to think electrical, not compression. neither of us has a compression gauge though, so we can't check at the moment. I had him check the resistance of his new plug wires, to make sure they are all good, they all came back between 6 and 8.5 ohms, which is a little larger of a distribution that I would have liked to see, but doubt that is the problem now.

any thoughts at all?
 


adsm08

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Could be an injector issue.
 

--weezl--

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it could be, I was thinking that for a while, and for some reason completely forgot...

might try running some seafoam through it...

does it sound like an injector issue if it goes from non existent to really bad in like a month though? keep in mind it wasn't just one day it did it bad, it was a steady progression over a month...
 

--weezl--

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so we threw some lucas injector cleaner into the tank, will see how that does, i think i'm going to get some seafoam anyways though...

I tried to read the codes on my autel scangauge type deal, but nothing came up, when I open the scan section of the thing it gives me a few options, DTC, FRZC, VIN, and another that gives me a few systems here and there, i forget what the letters are, vin comes up as vin, so i didn't check it, DTC and FRZC both say no codes found... not sure if there is a continuous memory like EEV-IV had, but like I said, no CEL...

I also disconnected the battery, pos and neg, and touched them together, just to make sure any codes are fully cleared. we also sprayed the MAF down with cleaner, maybe that was the issue? haven't taken it for a drive since though... we'll see
 

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