fouling plugs need help
Le Mans Master
Joined: Nov 2005
Posts: 6,993
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Throwing a ECM at it is silly till you get it on a scanner do see what's going on (Injector duty cycle, watch the O2's working, etc). I would also check compression in that cylinder vs. one that's not fouling. One cylinder fouling after you've swapped plugs/wires/injectors probably means valvetrain or compression issues.
Thread Starter
Burning Brakes
Joined: Dec 2006
Posts: 1,005
Likes: 90
From: FT. LAUDERDALE FL
i had it on the scanner no codes, o2 is fine, and what makes me think its something to do with the pcm sending a signal to the injector is because if we clean the plug, the car runs like a beast from 700rmp to 6800 no missing or anything, for a while then just starts missing again out of nowhere. and its always the same cylinder, we moved the coil, the plug, the wire, and the injector to a different cylinder and the problem stayed in #1
Throwing a ECM at it is silly till you get it on a scanner do see what's going on (Injector duty cycle, watch the O2's working, etc). I would also check compression in that cylinder vs. one that's not fouling. One cylinder fouling after you've swapped plugs/wires/injectors probably means valvetrain or compression issues.
Le Mans Master
Joined: Nov 2005
Posts: 6,993
Likes: 25
i had it on the scanner no codes, o2 is fine, and what makes me think its something to do with the pcm sending a signal to the injector is because if we clean the plug, the car runs like a beast from 700rmp to 6800 no missing or anything, for a while then just starts missing again out of nowhere. and its always the same cylinder, we moved the coil, the plug, the wire, and the injector to a different cylinder and the problem stayed in #1
Low compression would explain this, not allowing all the fuel to burn till it fouls the plug. If it's gas fouling there is either too much fuel entering or NOT being burned. I assume it's fuel fouled not oil.
Last edited by dougbfresh; Jan 7, 2010 at 04:12 PM.
Thread Starter
Burning Brakes
Joined: Dec 2006
Posts: 1,005
Likes: 90
From: FT. LAUDERDALE FL
checked the compression, its the same as the other cylinders, no loss of compression in the #1 cylinder,
Scanner I was referring to allows you to graph sensor input/output and computer in/out to see what the computer sees. Normal OBD readers and the DIC will not give you all this info. It's something not under computer control causing your problem. Do you ever get P0301 codes when the miss finally happens?
Low compression would explain this, not allowing all the fuel to burn till it fouls the plug. If it's gas fouling there is either too much fuel entering or NOT being burned. I assume it's fuel fouled not oil.
Low compression would explain this, not allowing all the fuel to burn till it fouls the plug. If it's gas fouling there is either too much fuel entering or NOT being burned. I assume it's fuel fouled not oil.
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Burning Brakes
Joined: Dec 2006
Posts: 1,005
Likes: 90
From: FT. LAUDERDALE FL
just went for a ride, after a few blocks it starts to miss, also it only does it under load, not if i just bring the rpms up in the shop, the problem occurs at lower rpm between 2-4k and part throttle, no problems at full throttle
Thread Starter
Burning Brakes
Joined: Dec 2006
Posts: 1,005
Likes: 90
From: FT. LAUDERDALE FL
if it was a drivetrain issue wouldnt it be there all the time, like i said when we clean the plug or put the new one in, the car runs perfect all the way up to 6800rpm no miss, nothing if i had a broken spring or something would it run that good with a clean or new plug?
Le Mans Master
Joined: Nov 2005
Posts: 6,993
Likes: 25
If a valve is not working right it could cause the problem. You issue is not with the computer. Whatever it is is not computer controlled or monitored. Sinice your not getting any P030x codes, the computer does not believe you have a miss. If you had a better scanner you can see the misfires per cylinder.
Thread Starter
Burning Brakes
Joined: Dec 2006
Posts: 1,005
Likes: 90
From: FT. LAUDERDALE FL
If a valve is not working right it could cause the problem. You issue is not with the computer. Whatever it is is not computer controlled or monitored. Sinice your not getting any P030x codes, the computer does not believe you have a miss. If you had a better scanner you can see the misfires per cylinder.
as far as i know we are using a better scaner its a snap on scaner its my mechanic friends and when we hook it up and go for a ride it shows how many misfires are in the #1 cylinder, in each cycle, when it happens we get 100-200 misfires in that cycle, and in a 5 min ride we may get 1100 or so misfires in the #1 cylinder,
also went for another ride and when misfire happens the engin light flashes my friend said that means its reading a misfire, but still no pcm codes in history, i dont understand it, we are just thinking that maybe since there are injector modules in the computer maybe one is not working right, and it is sending the wrong signal to the injector, it doesnt know its not working right so no code
Last edited by eric04; Jan 8, 2010 at 02:22 PM.
Le Mans Master
Joined: Nov 2005
Posts: 6,993
Likes: 25
as far as i know we are using a better scaner its a snap on scaner its my mechanic friends and when we hook it up and go for a ride it shows how many misfires are in the #1 cylinder, in each cycle, when it happens we get 100-200 misfires in that cycle, and in a 5 min ride we may get 1100 or so misfires in the #1 cylinder,
also went for another ride and when misfire happens the engin light flashes my friend said that means its reading a misfire, but still no pcm codes in history, i dont understand it, we are just thinking that maybe since there are injector modules in the computer maybe one is not working right, and it is sending the wrong signal to the injector, it doesnt know its not working right so no code
also went for another ride and when misfire happens the engin light flashes my friend said that means its reading a misfire, but still no pcm codes in history, i dont understand it, we are just thinking that maybe since there are injector modules in the computer maybe one is not working right, and it is sending the wrong signal to the injector, it doesnt know its not working right so no code
Did you swap coils on that cylinder too?
Thread Starter
Burning Brakes
Joined: Dec 2006
Posts: 1,005
Likes: 90
From: FT. LAUDERDALE FL
i just went out and checked the DIC codes again, and no codes at all, yes we changed the coil, the plug wire, the plug and injector to a different cylinder but the problem stayed in cylinder #1
Thread Starter
Burning Brakes
Joined: Dec 2006
Posts: 1,005
Likes: 90
From: FT. LAUDERDALE FL
