Misfire, not plugs or coilpack that I can tell
11-29-2009, 11:05 AM
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Misfire, not plugs or coilpack that I can tell
2000 manual S4, no mods, 185K miles (so you have to expect something will go wrong).
I'm out driving and everything is running fine. I stop for about 30 minutes and when I start up it's obviously missing a cylinder, very consistent, not firing at all as far as I could tell. I limp home and decide to change the plugs, which it needed anyway.
After sitting for a week, I swap the plugs. It starts up and runs great, so I go run some errands. I stop for about 30 minutes again and when starting it up, it begins misfiring again, not quite so bad but definitely missing *every* time. I Drive it about and by the time I get home, it's fine, then begins misfiring in the drive way before I turn it off.
Summary:
- When it misses, it misses every revolution, very consistent vibration and the VAGCOM counts them.
- Seemingly it can go away and act normal.
- Old plugs seemed good, just very old. No gum, not fouled.
- I swapped around two coilpacks but still missing on the same cylinder.
- No smoke
- Oil is the right color, no coolant in it as far as I can tell
Any thoughts?
I'm out driving and everything is running fine. I stop for about 30 minutes and when I start up it's obviously missing a cylinder, very consistent, not firing at all as far as I could tell. I limp home and decide to change the plugs, which it needed anyway.
After sitting for a week, I swap the plugs. It starts up and runs great, so I go run some errands. I stop for about 30 minutes again and when starting it up, it begins misfiring again, not quite so bad but definitely missing *every* time. I Drive it about and by the time I get home, it's fine, then begins misfiring in the drive way before I turn it off.
Summary:
- When it misses, it misses every revolution, very consistent vibration and the VAGCOM counts them.
- Seemingly it can go away and act normal.
- Old plugs seemed good, just very old. No gum, not fouled.
- I swapped around two coilpacks but still missing on the same cylinder.
- No smoke
- Oil is the right color, no coolant in it as far as I can tell
Any thoughts?
11-29-2009, 11:56 AM
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2000 manual S4, no mods, 185K miles (so you have to expect something will go wrong).
I'm out driving and everything is running fine. I stop for about 30 minutes and when I start up it's obviously missing a cylinder, very consistent, not firing at all as far as I could tell. I limp home and decide to change the plugs, which it needed anyway.
After sitting for a week, I swap the plugs. It starts up and runs great, so I go run some errands. I stop for about 30 minutes again and when starting it up, it begins misfiring again, not quite so bad but definitely missing *every* time. I Drive it about and by the time I get home, it's fine, then begins misfiring in the drive way before I turn it off.
Summary:
- When it misses, it misses every revolution, very consistent vibration and the VAGCOM counts them.
- Seemingly it can go away and act normal.
- Old plugs seemed good, just very old. No gum, not fouled.
- I swapped around two coilpacks but still missing on the same cylinder.
- No smoke
- Oil is the right color, no coolant in it as far as I can tell
Any thoughts?
I'm out driving and everything is running fine. I stop for about 30 minutes and when I start up it's obviously missing a cylinder, very consistent, not firing at all as far as I could tell. I limp home and decide to change the plugs, which it needed anyway.
After sitting for a week, I swap the plugs. It starts up and runs great, so I go run some errands. I stop for about 30 minutes again and when starting it up, it begins misfiring again, not quite so bad but definitely missing *every* time. I Drive it about and by the time I get home, it's fine, then begins misfiring in the drive way before I turn it off.
Summary:
- When it misses, it misses every revolution, very consistent vibration and the VAGCOM counts them.
- Seemingly it can go away and act normal.
- Old plugs seemed good, just very old. No gum, not fouled.
- I swapped around two coilpacks but still missing on the same cylinder.
- No smoke
- Oil is the right color, no coolant in it as far as I can tell
Any thoughts?
Boost leak, bad tank of gas? You have VAGCOM so is it giving you any codes besides misfires?
11-30-2009, 09:27 AM
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I just started having the same problem.
I have a 02 s4, no mods, with about 83,000.
Out of nowhere it started missing, limped it home and ran a diagnostic test on it. Ran a p0303 code (missing in cylinder 2)
Started going about it the cheap way, I replaced all the spark plugs. And also switched the coil pack on cylinder 2 with the one in cylinder 3, hoping that if the problem continued that when i did another diagnostic test, it would miss in cylinder 3 and i would know that the coil pack is bad.
Put everything back together, started the car, and the car was still missing. Ran the car a little, ran the diagnostic and it still says im missing in cylinder 2.
Now im frustrated and dont know what to do next. Maybe the wire that connects to the coil pack is bad...
I have a 02 s4, no mods, with about 83,000.
Out of nowhere it started missing, limped it home and ran a diagnostic test on it. Ran a p0303 code (missing in cylinder 2)
Started going about it the cheap way, I replaced all the spark plugs. And also switched the coil pack on cylinder 2 with the one in cylinder 3, hoping that if the problem continued that when i did another diagnostic test, it would miss in cylinder 3 and i would know that the coil pack is bad.
Put everything back together, started the car, and the car was still missing. Ran the car a little, ran the diagnostic and it still says im missing in cylinder 2.
Now im frustrated and dont know what to do next. Maybe the wire that connects to the coil pack is bad...
11-30-2009, 11:47 AM
#5
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many many many times a boost leak is the cause of misfires and boost leaks are pretty common. You guys should check that first.
Maninhouse: the connections don't typically go bad but the coil packs themselves can fail. Easy way to test this is to take the cyl2 coil pack an put it on another cyl. If the misfire moves with the coilpack that's your answer. If not CHECK FOR BOOST LEAKS
Maninhouse: the connections don't typically go bad but the coil packs themselves can fail. Easy way to test this is to take the cyl2 coil pack an put it on another cyl. If the misfire moves with the coilpack that's your answer. If not CHECK FOR BOOST LEAKS
11-30-2009, 01:03 PM
#6
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I think it usually throws codes, but did you try swapping you ignition modules and see if the misfire moves? There are two of them on your air box. swap the wiring between them and give it a shot.
Hope that helps
Cheers
Massboykie
11-30-2009, 05:05 PM
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swapping coil packs didn't help. Code is P305 (Still Cyl #5)
Thanks guys, I will check for a boost leak (haven't done that ever, will look to the archives)
Anyway, I still can't get past that it is just Cyl #5 that is reported as missing and you can feel that it's very consistently missing. I did swap coils with another cyl.
VAGCOM reports:
16689 - Cylinder 5: Misfire Detected
P0305 - 35-00 - -
All other cyl's report zero misfires, where cyl #5 will just keep counting up. Before and after the swap.
Massboykie,
Thanks for the suggestion, I will look into the ignition modules, did not do that yet.
Anyway, I still can't get past that it is just Cyl #5 that is reported as missing and you can feel that it's very consistently missing. I did swap coils with another cyl.
VAGCOM reports:
16689 - Cylinder 5: Misfire Detected
P0305 - 35-00 - -
All other cyl's report zero misfires, where cyl #5 will just keep counting up. Before and after the swap.
Massboykie,
Thanks for the suggestion, I will look into the ignition modules, did not do that yet.
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11-30-2009, 05:40 PM
#8
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mainhousejake,
Any chance you have the manuals? I hate their search but after looking hard enough there are some trouble shooting guides. Items like checking for signal and short in the wiring. I'll let you know if I find anything...
TPL_S4
Any chance you have the manuals? I hate their search but after looking hard enough there are some trouble shooting guides. Items like checking for signal and short in the wiring. I'll let you know if I find anything...
TPL_S4
11-30-2009, 08:41 PM
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yeah, im going to check the wiring next. i also saw that it might be the fuel injector plug on that cylinder too.
ill also check the throttle body boot too, but i dont thinks that will be the case. def never hurts to check thou.
ill also check the throttle body boot too, but i dont thinks that will be the case. def never hurts to check thou.