V6 (1994-2004) Mustangs Technical discussions on the 3.8L and 3.9L V6 torque monsters

bad vibration, misfiring

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Old 11-29-2012, 06:47 PM
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snooky012002
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Exclamation bad vibration, misfiring

ok so i have a 2000 stang 3. auto tranny, got on it real hard one day and had a bad vibration in motor ever since, have changed plugs, wires tried different coil pack, still know i help i do know that its not firing on all cylinders from pulling wires off coil, i lined tdc on #1 plug and the timing mark on the hb damper didnt line up with the mark beside crank shaft sensor not sure if it will havent been able to find timing marks anywere... i have ran sea foam in oil and fuel, cleaned maf throttle body.. any help would muh be appreciated im tired of racking my brain on this....
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Old 11-29-2012, 08:01 PM
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jthorn9
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You may have the early symptoms of a failing head gasket. You need to rum a compression check and see how things look.

These cars don't have timing marks, the timing is controlled by the ECU and not the crank like older cars.

It's also possible the timing chain may be bad and isn't properly aligned. This is a long shot possibility but I'd do the compression first and foremost.
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Old 11-29-2012, 09:31 PM
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snooky012002
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im doing one tomorrow for sure will post results
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Old 11-29-2012, 09:55 PM
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jthorn9
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Yeah, the key here is the problems started after getting hard on the car. Usually gaskets are the culpriate here, more specifically head gaskets. But timing chains aren't out of the question either but those are usually slow to cause issues.
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Old 11-30-2012, 10:00 AM
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snooky012002
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ok this is what ive got
driver side front to back
1:135 plug is dry
2:145 plug is dry
3:140 plug is dry

passenger
1:140 covered in gas
2:140 covered in gas, the end of plug was bent together where you gap it
3:135 covered in gas, plug was broke in half when i pulled it out

so im thinking injectors, i know the batter is bad ive had it tested but most days it starts so i havent changed it, ive read a bad battery will cause misfire cuz injectors aint working right... any clues
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Old 11-30-2012, 01:02 PM
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jthorn9
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That's odd to have broken plugs. It's plausible it could be the injectors but it could be something else causing it.
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Old 11-30-2012, 01:04 PM
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I was just thinking, if the plugs are coverd in gas that's a sign of failure to detonate. Replace all the plugs, wires, and ignition module. It's possible that any of of those could be causing the problem. The fuel injectors are very unlikely unless they're clogged and that would be causing a different problem.
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Old 11-30-2012, 01:29 PM
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Derf00
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Originally Posted by snooky012002
ok this is what ive got
driver side front to back
1:135 plug is dry
2:145 plug is dry
3:140 plug is dry

passenger
1:140 covered in gas
2:140 covered in gas, the end of plug was bent together where you gap it
3:135 covered in gas, plug was broke in half when i pulled it out

so im thinking injectors, i know the batter is bad ive had it tested but most days it starts so i havent changed it, ive read a bad battery will cause misfire cuz injectors aint working right... any clues
You mentioned some plugs weren't firing in your OP. Do the wet plugs coincide with cylinders not firing? I would think if you have that severe of a misfire that you would have a CEL on in the dash (unless it is burnt out).

Check the OBDII system for codes.
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Old 11-30-2012, 10:16 PM
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snooky012002
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so i pulled intake off today upper and lower cleaned them all real good clean injrctors they were dirty checked them to make sure there working, put it all back together started it, it shaked bad upon starting and smoothed out but there is still a vibration and when u rev it up u can feel it start in motor and followthroughthe car, i did drive it and its not as bad as it was.. now im leaking water from back of motor and getting water in oil pretty fast i didnt replace gaskets so doing that over weekend thinking i didnt tighten bolts to specs done it by feel nottorch wrench... oh i pulled all the plug wires off they are all firing now
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Old 11-30-2012, 10:18 PM
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@derf the light isnt burnt out there is code now but thats cuz i had maf unhooked thats why its been so hard cuz of there being no codes,,,,
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