2007 S8 misfires cylinder 9 and 10
08-03-2020, 10:09 AM
#1
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2007 S8 misfires cylinder 9 and 10
I have significant misfires with flashing check engine, very rough idle and smell of gas in exhaust. In addition to misfire codes for 9 and 10, I have following codes. I swapped out coils from other cylinders and misfires stay with 9 and 10, so at first check does not appear to be a bad coil.
Problem came on suddenly while cruising on the freeway. Other ideas to troubleshoot? I am at 86k miles.
Other codes:
Fuel Rail/system pressure P0087 008 too low
Fuel Rail / system pressure P0087 002 too low intermittent
Fuel pressure sensor (G247) P119A - 002 - Malfunction
Check coding of ECUs on Powertrain data bus P1647 -001 Intermittent
Problem came on suddenly while cruising on the freeway. Other ideas to troubleshoot? I am at 86k miles.
Other codes:
Fuel Rail/system pressure P0087 008 too low
Fuel Rail / system pressure P0087 002 too low intermittent
Fuel pressure sensor (G247) P119A - 002 - Malfunction
Check coding of ECUs on Powertrain data bus P1647 -001 Intermittent
08-03-2020, 10:27 AM
#2
AudiWorld Wiseguy
Those error codes suggest failed high pressure fuel pumps. Does it rev/run ok whilst unloaded?
Have you run some fuel injector cleaner through it recently?
Could also be coked up inlet ports, or some bad injectors, although less likely given the fuel rail low pressure error codes.
Have you run some fuel injector cleaner through it recently?
Could also be coked up inlet ports, or some bad injectors, although less likely given the fuel rail low pressure error codes.
08-03-2020, 10:32 AM
#3
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What do you mean while unloaded? While on the free way when the check engine first started flashing, it did not seem too bad in terms of how it was running. Only thing I noticed is when I would accelerate there would be some minor hesitation/vibration. Once I got off freeway and came to a stop idling is when things seemed much worse.
No on fuel injector cleaning. Have not done that in ages. I usually opp for an "Italian tune up" and drive it hard to clear the pipes after my wife runs it around town taking my daughter to play dates and what not.
No on fuel injector cleaning. Have not done that in ages. I usually opp for an "Italian tune up" and drive it hard to clear the pipes after my wife runs it around town taking my daughter to play dates and what not.
08-03-2020, 01:45 PM
#5
Had a similar issue, 4-5 and 9-10 misfires, ran liqui moly injector cleaner , holding revs between 2-3k for a bit and cleaned it right out. Thats what worked for me, must've had blockages in high pressure pumps/injectors.
08-03-2020, 05:23 PM
#6
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Did you have dead cylinders or sporadic misfires? Mine are being flooded with fuel and constantly misfiring.
08-03-2020, 08:17 PM
#7
I had pretty steady misfires, even at idle as well as max fuel trims caused by a post maf vacuum leak. The vacuum leak caused my motor to run very rich, which combined with the blockage led to my issues.
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08-03-2020, 08:18 PM
#8
AudiWorld Wiseguy
As you have VCDS, check the fuel rail pressure after engine shutdown. It shouldn’t drop, or at most very slowly.
Again a strong dosing of injector cleaner is the first fix to try.
08-08-2020, 05:01 AM
#9
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If those cylinders are flooding and not firing at all, then coupled with low fuel rail pressure suggests it could be a couple of stuck open injectors.
As you have VCDS, check the fuel rail pressure after engine shutdown. It shouldn’t drop, or at most very slowly.
Again a strong dosing of injector cleaner is the first fix to try.
As you have VCDS, check the fuel rail pressure after engine shutdown. It shouldn’t drop, or at most very slowly.
Again a strong dosing of injector cleaner is the first fix to try.
car is headed to Redline Speed Worx in NJ Monday. Will keep this thread updated.
08-12-2020, 03:05 AM
#10
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Diagnosis was injectors, they said the cylinders were totally flooded with fuel yet I was getting spark. Everything else checked out. Flaps on manifold in good shape. Decided to have all 10 injectors replaces, carbon cleaning and oil filter housing seal replaced. Work is getting done now.