07 S8 Lean code and misfires
03-13-2020, 11:20 PM
#11
AudiWorld Member
Thread Starter
Wanted to provide an update, looks like the problems have been solved. The fuel trim issue ended up being a massive vacuum leak on the driver intake hose. The connection for the sound baffle had a crack on the bottom side, smoked the manifold with air intake tubes attached the second time and it came pouring out. Must say the sound damper /muffler thing is a useless stupid design. Patched up the leak while awaiting a new pipe and no more issues. Fuel trim holding steady at +5% on idle. Huge improvement over the maxed out +25 I had before.
Now for the misfires, believe it or not the fuel system cleaner worked. Used the liquimoly brand and let the car idle for about an hour, lightly held the revs up intermittently, then back to idle... Suddenly revs dropped to 2-300 then shot up to 2000 and hung there, light tap on the throttle , dropped to 640 and smoothed out beautifully. Mustve had a nasty clog somewhere in the system, still can't believe after all the diagnostics I went through the simple fix worked. The lesson for the next person is check for vacuum leaks everywhere and give the fuel system a nice clean. Car is driving great now, thank you all for the help.
Now for the misfires, believe it or not the fuel system cleaner worked. Used the liquimoly brand and let the car idle for about an hour, lightly held the revs up intermittently, then back to idle... Suddenly revs dropped to 2-300 then shot up to 2000 and hung there, light tap on the throttle , dropped to 640 and smoothed out beautifully. Mustve had a nasty clog somewhere in the system, still can't believe after all the diagnostics I went through the simple fix worked. The lesson for the next person is check for vacuum leaks everywhere and give the fuel system a nice clean. Car is driving great now, thank you all for the help.
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BASARAB (03-14-2020)
03-13-2020, 11:48 PM
#12
Wanted to provide an update, looks like the problems have been solved. The fuel trim issue ended up being a massive vacuum leak on the driver intake hose. The connection for the sound baffle had a crack on the bottom side, smoked the manifold with air intake tubes attached the second time and it came pouring out. Must say the sound damper /muffler thing is a useless stupid design. Patched up the leak while awaiting a new pipe and no more issues. Fuel trim holding steady at +5% on idle. Huge improvement over the maxed out +25 I had before.
Now for the misfires, believe it or not the fuel system cleaner worked. Used the liquimoly brand and let the car idle for about an hour, lightly held the revs up intermittently, then back to idle... Suddenly revs dropped to 2-300 then shot up to 2000 and hung there, light tap on the throttle , dropped to 640 and smoothed out beautifully. Mustve had a nasty clog somewhere in the system, still can't believe after all the diagnostics I went through the simple fix worked. The lesson for the next person is check for vacuum leaks everywhere and give the fuel system a nice clean. Car is driving great now, thank you all for the help.
Now for the misfires, believe it or not the fuel system cleaner worked. Used the liquimoly brand and let the car idle for about an hour, lightly held the revs up intermittently, then back to idle... Suddenly revs dropped to 2-300 then shot up to 2000 and hung there, light tap on the throttle , dropped to 640 and smoothed out beautifully. Mustve had a nasty clog somewhere in the system, still can't believe after all the diagnostics I went through the simple fix worked. The lesson for the next person is check for vacuum leaks everywhere and give the fuel system a nice clean. Car is driving great now, thank you all for the help.
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