1995 A6 Avant 2.8 misfire problem

bwright138 · 05-11-2012, 08:39 AM

Weird problem actually. Occasionally, for no obvious reason, the enginge will start running on only 4 or 5 cylinders, and all sorts of awful noises will come out of the tail pipe. But the issue is that it is intermittent, will last about 30 seconds, and then it runs fine.

I have a new timing belt within the last 20k miles, and when this problem first started occurring I replaced the plugs, wires, and ignition coil. I'm going to check vacuum lines this morning, and I've heard that the engine coolant temp sensor could also be a problem. Aside from this, I'm kind of lost. O2 sensor(s)? Fuel delivery problem? Thanks for your suggestions.

upallnight · 05-12-2012, 12:48 PM

Do you have a check engine light on? Did you try scanning for any DTC?

Prospeeder · 05-12-2012, 09:53 PM

There is a part number 4A0905351 on the fire wall passenger side.

The power output stage is an electronic switch that controls the ignition coil's discharge. So it could just have a bad spot on the portions controlling the missing cylinders

bwright138 · 05-19-2012, 11:39 AM

It was the crankshaft position sensor in case anyone else has this problem.

egp320i · 05-21-2012, 02:10 AM

BTDT, they last anywhere from 60-100K. When it goes motronics cannot understand the relationship and thus it goes into limp mode.

05-12-2012, 09:53 PM	#3
Prospeeder AudiWorld Senior Member Garage is empty, add now Join Date: Aug 2011 Posts: 862	There is a part number 4A0905351 on the fire wall passenger side. The power output stage is an electronic switch that controls the ignition coil's discharge. So it could just have a bad spot on the portions controlling the missing cylinders __________________ 1992 Audi 100 CS Quattro 1991 Audi 200 Turbo 1999 Audi A6 Avant 1998 Audi A4 quattro

05-21-2012, 02:10 AM	#5
egp320i AudiWorld Super User 1994 Audi 90 My Garage Join Date: Jan 2002 Location: E.Idaho Posts: 4,383	BTDT, they last anywhere from 60-100K. When it goes motronics cannot understand the relationship and thus it goes into limp mode. __________________

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05-12-2012, 12:48 PM	#2
upallnight AudiWorld Member Garage is empty, add now Join Date: Dec 2002 Posts: 141	Do you have a check engine light on? Did you try scanning for any DTC?

05-19-2012, 11:39 AM	#4
bwright138 AudiWorld Newcomer Garage is empty, add now Join Date: May 2012 Posts: 2	It was the crankshaft position sensor in case anyone else has this problem.