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need a hand on a 2004 8.1L spark knock

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Old 09-26-2018, 09:32 PM
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i got the suv out of Medina NY . payed 2300$ for it . it had 30K miles on it and was not even 2 year old . sold it around 5 yeas latter for 5K with 80K miles on it . yes that'* not your stander front end . had to stand out in my line of work so it was on TV many times
i have so many pics of every step when fixing this truck . youtube was not a thing back then
Old 09-27-2018, 01:46 AM
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That'* cool
Old 09-29-2018, 10:43 PM
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so got the motor running but it was very late here so i just ran the motor for 30 mins for brake in . got every thing up to temp . have some small stuff to work on . well take it for a test drive latter to see if the sound is still there
going to play with it some more in the driveway to make sure the motor is ready for the road . as you can see its a big tow bill . O and the tool i order i had to cut the end off it but it worked grate so i am going to make a post here just for that to save others money
Old 09-30-2018, 12:18 AM
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Cool, looking forward to it.

Good luck on the test drive!
Old 09-30-2018, 11:48 AM
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my oil psi is 10 psi higher and this has made a oil leak on a cooler line so i cant test drive
i still have a very bad intermittent miss with no code . i unpluged each coil pack 1 at a time and cant find it
there was a not so bad intermittent miss before but now its all most a real full time miss
fuel trim is better but still -5 on LTFT on both sides and goes -2 if i pull the oil dipstick why running

i cant get the motor to make the tapping sound and ran it for 30 mins again playing with load / no load but i am not ready to call this a win just yet
i want to find this miss and take it on a 30 mile drive with no sound before i call this a win

oil psi is alot better . cold 60 at all times and when hot 20 at idle so thats 10 psi better at idle
Old 09-30-2018, 01:50 PM
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Good news on the oil pressure.

Is the miss only at idle?
Old 09-30-2018, 07:28 PM
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no the miss seems to be at all rpms but if i put it in gear and let idle or 1200 or so rpm under load you can really tell its there

i still think i have 1 of 5 things

wiring from PCM to fuel injector or coil pack
fuel injector cutting out when hot .. think this 1 more as that wire that was to ground before .
fuel injector or coil driver in PCM going out or not sending the right apms
or 1 of the coil wires is bad that i put back on
lagging O2 sensor but again not sure what to look for when seeing the swing on how fast from .01 to .09 i should see but i do have 1 that seems to lag alot more then the other
i think i need to get a Auto Scope to see what every thing is doing to find this . and giving i am not 100% sure what stopped the knocking sound i must make sure if what made it
happen in the first place is not still there . the scope is 200$ and would take a month in shipping time


i never did a crank relearn procedure on this motor as i never know if i needed too . after looking at all most every yoututbe video there is its starting to make me think i need it
so that maybe why the motor rolls over a few more times when starting
Old 09-30-2018, 10:25 PM
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Originally Posted by terry735001
i never did a crank relearn procedure on this motor as i never know if i needed too . after looking at all most every yoututbe video there is its starting to make me think i need it
so that maybe why the motor rolls over a few more times when starting
I'd ask the guy that programmed your PCM about this one. It might need to relearn or might not be able to or somewhere in the middle.
Old 10-03-2018, 12:20 PM
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so i order a low cost scope and it well be a month before it gets here
i well use it to help find the miss

i got the oil line fixed and did some more testing and the sound is gone ... the more i run it the better the fuel trims look -4 on driver side and -3 on passenger side on LTFT at idle . both go to 0 at 1200 rpm so that looks really
so i cant tell if the miss is fuel or spark

no matter what i do or unplug i cant find it on the old ways of doing things .
the exhaust is still really hot and smells rich/funny but not as bad as before but i think the miss is spark
its like i have a coil firing every 2ed time like fire miss fire miss . its really funny and this miss maybe what hurt my motor in the first place

whats going on has to be some thing you dont see every day and so i have some tests i well do when the tool gets here
Old 10-03-2018, 01:26 PM
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Cool, let us know what happens!


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