Random Misfires below 1300 rpm. All Cylinders
#1
Random Misfires below 1300 rpm. All Cylinders
2004 Audi A4 1.8t tiptronic
In park, the engine flashes the CEL and runs rough. In drive but at a stop, it still runs rough as if there are small mis-fires occuring. I've seen it flash the CEL in drive at a stop but it hasn't done it since I changed the coil packs and the plugs. Above 1300 rpm, it drives normal. No known misfires underload. Fuel pressure seems normal (I can only tell by driving though)
Previous attempts to fix include:
-New MAF
-New Plugs
-New R coil packs
-New Bypass/diverter valve
-Vac leak check (PASSED)
-New Fuel filter
-Tried different fuel (shell brand)
-Did a Vag Com T.B.A.
Only codes thrown are the p0301-p0304 codes including random misfires code (p0300)
It's not throwing an o2 specific code or a TB code. ECU is not trimming fuel either. Its not a ICM because the car is too new.
My thoughts have been pointed towards a Cam Sensor but it's to my understanding that the cam sensor has it's own code. I'm too green to know what feeds the power to the coil packs otherwise, I would research the power source.
I would like to add... the random misfires started at higher elevations. The beggining stages were very week pulsing in the idle dropping. It took about 3 mos for it to get as bad as it is now. Before the idle pulsing issue started, I was dealing with a whining fuel pump. I changes the fuel filter and the whining went away. My next concern is that I damaged the fuel pump by letting the clogged/bad fuel filter go as long as I did. Perhaps the fuel pump is the cause of the misfiring below 1300rpm (idle range)
I NEED some serious help! Has anyone had these identical or closely related symptoms before?
In park, the engine flashes the CEL and runs rough. In drive but at a stop, it still runs rough as if there are small mis-fires occuring. I've seen it flash the CEL in drive at a stop but it hasn't done it since I changed the coil packs and the plugs. Above 1300 rpm, it drives normal. No known misfires underload. Fuel pressure seems normal (I can only tell by driving though)
Previous attempts to fix include:
-New MAF
-New Plugs
-New R coil packs
-New Bypass/diverter valve
-Vac leak check (PASSED)
-New Fuel filter
-Tried different fuel (shell brand)
-Did a Vag Com T.B.A.
Only codes thrown are the p0301-p0304 codes including random misfires code (p0300)
It's not throwing an o2 specific code or a TB code. ECU is not trimming fuel either. Its not a ICM because the car is too new.
My thoughts have been pointed towards a Cam Sensor but it's to my understanding that the cam sensor has it's own code. I'm too green to know what feeds the power to the coil packs otherwise, I would research the power source.
I would like to add... the random misfires started at higher elevations. The beggining stages were very week pulsing in the idle dropping. It took about 3 mos for it to get as bad as it is now. Before the idle pulsing issue started, I was dealing with a whining fuel pump. I changes the fuel filter and the whining went away. My next concern is that I damaged the fuel pump by letting the clogged/bad fuel filter go as long as I did. Perhaps the fuel pump is the cause of the misfiring below 1300rpm (idle range)
I NEED some serious help! Has anyone had these identical or closely related symptoms before?
Last edited by pos04audiA41.8; 12-22-2009 at 04:18 PM. Reason: Forgot additional information
#3
It's completely stock.
I researched another thread and this guy had what seemed to be the same problem as mine. He changed the Vac Check valve and was good as new. I would agree with this but I've had the car vac leak checked twice.
I researched another thread and this guy had what seemed to be the same problem as mine. He changed the Vac Check valve and was good as new. I would agree with this but I've had the car vac leak checked twice.
Last edited by pos04audiA41.8; 12-22-2009 at 09:08 PM.
#6
If you're sure that the car is Vac leak tested and the coil packs and spark plugs are new... then check the spark plug to be fouled by oil from a faulty head/valve cover gasket. It could also be the whole harness.
#7
I appreciate all of the comments posted... Some seam a little tedious and contradict tests already done and others are thougthful considerations. I'm beggining to realize how picky these cars can be...
At any rate, I look forward to testing some of these theories and I hope to bring good news. If anyone has any further comments they would like to post, please! By all means!
At any rate, I look forward to testing some of these theories and I hope to bring good news. If anyone has any further comments they would like to post, please! By all means!
#8
So if the TPS is jacked, I would likely have to replace the entire TB right? It's to my understanding that the 04' A4 1.8 has a more "disposable" style that doesn't permit much maintenance.
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