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View Full Version : Misfires Don't Want to Go Away!


bigbseehagen
06-30-2014, 09:32 AM
Ok, so I have a B6 S4 that I purchased. All of a sudden it started to have a rough idle one day and the CEL started flashing. So I ran the codes and got misfires. So I changed the plugs to NGK Iridium plugs, changed all of the coils, changed the pcv valve, changed the valve cover gaskets and painted them, swapped injectors around, changed the oil to lubromoly, and there is still misfires on cylinders 1 and 3. When I changed the plugs before I changed the coils too I tested it to see what was happening. There were now misfires on 1,2,3,5,7. Then I changed the coils and now only 1,3. Can someone help me out? I took to an audi shop not the dealership and they could not find the issue either. It has a loud start up rattle as well. The weird thing is that it runs fantastic above 1,000 RPM with no performance loss. Once it is warmed up and has been run for about 20 minutes, when you come to a stop in gear it starts to misfire. if you put it in neutral then it can prevent it at times. So I have no idea what to do. I do not want to take it to the dealership and waist 150.00 just to be told they don't know or have them give me a guess.

http://www.audizine.com/gallery/data/500/medium/S454.jpg
http://www.audizine.com/gallery/data/500/medium/S4_Engine_Bay.jpg
Furly
07-02-2014, 09:21 AM
I have a similar issue and it ended up being my head gasket leaking coolant into the cylinder and causing misfiring.

New plugs and coil packs fixed it for a week. Then it came back. Pulling my head this week.
bigbseehagen
07-02-2014, 09:24 AM
How did you diagnose it?
bigbseehagen
07-02-2014, 09:24 AM
I have a similar issue and it ended up being my head gasket leaking coolant into the cylinder and causing misfiring.

New plugs and coil packs fixed it for a week. Then it came back. Pulling my head this week.

How did you diagnose it?
Furly
07-02-2014, 01:20 PM
You can do a cylinder leak down test. And a compression test. Those two will tell you if you are leaking into the cylinder and if you have compression issues (which b6 s4 is known for).
Also if your timing chain components are bad you could have skipped a tooth, this also causes misfiring. I would start with cylinder leak down test and compression test first and go from there.
Furly
07-16-2014, 06:33 PM
You ever get this sorted? The rattle at start up is usually the timing chain rattling due to broken guides and components.