need a hand on a 2004 8.1L spark knock
#21
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a few more things . i did all the tests he ask on the fuel injector and they test ok . 12.7 oms when hot to 13.oms each when hot . not hot all test 12.7 so there are showing the same when cold
unplugged each fuel injector 1 at a time then snap WOT and still get the sound but with the lower HP its alot lower
found 2 used MAF sensors at a junk yard today tryed them and both saying the same numbers as the old 1 so that test did not help
BUT some thing stands out to me .. when pulling the old MAF out it has dust on it again and i cleaned it days ago . some how i am getting air into the system before the MAF sensor but before the air filter
i have to make sure there is not new air getting in form behind the MAF . i used starting fluid and LP every where on the motor to look for bad air getting in
i did not say this before but it does sound like the motor is having a hard time pulling air in but i pulled every thing apart and cleaned every thing when i had it off the motor
fuel trim at 1500 RPM show 0 but both LTFT but go - on driver side to 6 to 7 and passenger side 4 to 5 . its pulling the fuel back at idle and making it run sick some
O guy at stop cant look at RV tell all most a week from now
unplugged each fuel injector 1 at a time then snap WOT and still get the sound but with the lower HP its alot lower
found 2 used MAF sensors at a junk yard today tryed them and both saying the same numbers as the old 1 so that test did not help
BUT some thing stands out to me .. when pulling the old MAF out it has dust on it again and i cleaned it days ago . some how i am getting air into the system before the MAF sensor but before the air filter
i have to make sure there is not new air getting in form behind the MAF . i used starting fluid and LP every where on the motor to look for bad air getting in
i did not say this before but it does sound like the motor is having a hard time pulling air in but i pulled every thing apart and cleaned every thing when i had it off the motor
fuel trim at 1500 RPM show 0 but both LTFT but go - on driver side to 6 to 7 and passenger side 4 to 5 . its pulling the fuel back at idle and making it run sick some
O guy at stop cant look at RV tell all most a week from now
#22
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ok for the FUN of it i pulled muffler and used a cam to look inside it and up the pipes and every thing looks good
pulled ALL fuel injector left fuel line on and rolled over the motor to see them all working . that look good with none dripping fuel out the ends when letting it set
then moved them again to see if LTFT moved over to the other bank and they stayed the same
when they where out i could see right in to the intake valves and used my cam again to take a good look at them and all looks good
moved coils 1 by 1 why motor was running to see if LTFT would move with it and it did not so i am just about as sure as i can be that all coils are good
put RMP tester on wires at end next to spark plug and numbers holding the same and not jumping around
this is really starting to get me down
pulled ALL fuel injector left fuel line on and rolled over the motor to see them all working . that look good with none dripping fuel out the ends when letting it set
then moved them again to see if LTFT moved over to the other bank and they stayed the same
when they where out i could see right in to the intake valves and used my cam again to take a good look at them and all looks good
moved coils 1 by 1 why motor was running to see if LTFT would move with it and it did not so i am just about as sure as i can be that all coils are good
put RMP tester on wires at end next to spark plug and numbers holding the same and not jumping around
this is really starting to get me down
#23
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True Car Nut
I get what the PCM guy is saying. Sounds like he'* got his head in the right place for your load. That having been said, we're running out of other things that I can think of, and you've been through more of that engine than many ever would.
The spark plugs are gapped .060", right?
The spark plugs are gapped .060", right?
#24
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yeah the PCM guy has his own website and been doing it for years but with that being said i am thinking of trying a new PCM from him just so i have a back up
my friend was off this weekend so we still tried hard to find any thing wrong .
if i make a miss the LTFT go high but when we pulled the muffler and ran the motor we could hear a some times miss is still on the driver side
i dont know if the miss is just the PCM cutting fuel to stay at idle to keep RPM low
i just dont have the tools i would need to do more testing so if the guy at the shop has a opening this week i well take the RV there
i am thinking i well make a new video of what its doing and what i have to do to get the sound
i have a new part coming in today its a long shot but its some thing that needs fixed any ways
my friend was off this weekend so we still tried hard to find any thing wrong .
if i make a miss the LTFT go high but when we pulled the muffler and ran the motor we could hear a some times miss is still on the driver side
i dont know if the miss is just the PCM cutting fuel to stay at idle to keep RPM low
i just dont have the tools i would need to do more testing so if the guy at the shop has a opening this week i well take the RV there
i am thinking i well make a new video of what its doing and what i have to do to get the sound
i have a new part coming in today its a long shot but its some thing that needs fixed any ways
#25
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so stopped by the repair shop today to make sure the guy still wanted to look at the RV tomorrow . hes like sure just drop it off . his seem to forget i live in it and if i bring it to him i would have to set with it or in his office till he was done . guess that did not fly well with him . and setting in his drive way fro a hole day or walking home in the FL sun did not set well with me so i am going to have to find a way to do this my self i guess .
$1K obd2 scanner here i come... and in the end still may not know what i am looking at
any ways did a 20mile test drive with it today and the sound is still there just the same as in the 1 video .
and again only makes the sound when under load at low RPM . no other time or RPM or gear
its about 400$ to reman the top end and install new cam so i may just do that as the sound has not moved and i dont have much else to try
$1K obd2 scanner here i come... and in the end still may not know what i am looking at
any ways did a 20mile test drive with it today and the sound is still there just the same as in the 1 video .
and again only makes the sound when under load at low RPM . no other time or RPM or gear
its about 400$ to reman the top end and install new cam so i may just do that as the sound has not moved and i dont have much else to try
#26
Senior Member
True Car Nut
so stopped by the repair shop today to make sure the guy still wanted to look at the RV tomorrow . hes like sure just drop it off . his seem to forget i live in it and if i bring it to him i would have to set with it or in his office till he was done . guess that did not fly well with him . and setting in his drive way fro a hole day or walking home in the FL sun did not set well with me so i am going to have to find a way to do this my self i guess .
$1K obd2 scanner here i come... and in the end still may not know what i am looking at
any ways did a 20mile test drive with it today and the sound is still there just the same as in the 1 video .
and again only makes the sound when under load at low RPM . no other time or RPM or gear
its about 400$ to reman the top end and install new cam so i may just do that as the sound has not moved and i dont have much else to try
$1K obd2 scanner here i come... and in the end still may not know what i am looking at
any ways did a 20mile test drive with it today and the sound is still there just the same as in the 1 video .
and again only makes the sound when under load at low RPM . no other time or RPM or gear
its about 400$ to reman the top end and install new cam so i may just do that as the sound has not moved and i dont have much else to try
#27
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I 100% under stand the feeling on the ECM
i only have so much money left to try to find whats wrong . really its 1 last shot before i have to set for monthssss to save up to try again
i think the chance is higher of now the sound is in the motor then a ecm
i know the sound does sound like a spark knock but its not moving and its staying in the same spot
for the fun of it i dropped the trans today to make sure there was no crack in the flywheel . it all looks good
with the trans out of the way i can install a new cam. lefters .chain. and just redo the top end .
i know i had a good look at the cam when i had the intake off but thats all it was is a look
i feel some thing is just starting to get out of spec so its maybe some thing that just cant stand out by looking at it
so over the next few days i am just going to pull EVERY thing apart and 100% make sure its not the motor
why i am in there i well try to find why my fuel trims keep going low as it maybe a gasket that has a vacuum leak inside the motor as i have no vacuum leak out side or a crack in the block or some thing not so god
it is driving me nuts to have to take apart a motor thats running so good and sounds good with lots of power . but as soon as i try low end power it taps .
i well keep you up to date tho
i only have so much money left to try to find whats wrong . really its 1 last shot before i have to set for monthssss to save up to try again
i think the chance is higher of now the sound is in the motor then a ecm
i know the sound does sound like a spark knock but its not moving and its staying in the same spot
for the fun of it i dropped the trans today to make sure there was no crack in the flywheel . it all looks good
with the trans out of the way i can install a new cam. lefters .chain. and just redo the top end .
i know i had a good look at the cam when i had the intake off but thats all it was is a look
i feel some thing is just starting to get out of spec so its maybe some thing that just cant stand out by looking at it
so over the next few days i am just going to pull EVERY thing apart and 100% make sure its not the motor
why i am in there i well try to find why my fuel trims keep going low as it maybe a gasket that has a vacuum leak inside the motor as i have no vacuum leak out side or a crack in the block or some thing not so god
it is driving me nuts to have to take apart a motor thats running so good and sounds good with lots of power . but as soon as i try low end power it taps .
i well keep you up to date tho
#28
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True Car Nut
Cool, looking forward to finding out what fixes this.
#29
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so the FL weather let up to where we could work on it
now i have worked on many motors but when it comes to cylinder bore measurement and how much play should be in the piston i do not know what i am doing
but all the piston have alot of play in them . so much so i can see the rings . but i do not know when every thing is hot if this gape goes away
with it cold i can move all the pistons around and get them to make sound . there is no up and down play . all the play is side to side and the type of play you would see with piston slap
i may have found my -7% fuel trim as i found 2 exhaust manifold gasket leaks 1 on each side of the motor . they where in a way that i could have never found them but they where small
its night time now but i well see if i can take some pics latter
now i just have to keep taking it apart to get to the 280lbs so me and a friend to get it in the back of my car to take to the shop
now i have worked on many motors but when it comes to cylinder bore measurement and how much play should be in the piston i do not know what i am doing
but all the piston have alot of play in them . so much so i can see the rings . but i do not know when every thing is hot if this gape goes away
with it cold i can move all the pistons around and get them to make sound . there is no up and down play . all the play is side to side and the type of play you would see with piston slap
i may have found my -7% fuel trim as i found 2 exhaust manifold gasket leaks 1 on each side of the motor . they where in a way that i could have never found them but they where small
its night time now but i well see if i can take some pics latter
now i just have to keep taking it apart to get to the 280lbs so me and a friend to get it in the back of my car to take to the shop
#30
Senior Member
True Car Nut
Cold pistons will move a little. A little more on big pistons and a little more on engines that are going to have some extra stress for some reason. Like yours.