shwndh

I've got a 03' 3.0 A4 and since I've gotten this car about 1.5 years ago, i've had an issue with random misfires at idle. You can't really tell that the car is misfiring at all - the only symptom is that the CEL will come on ocassionally. Here are the codes:

16684 Random/Multiple Cylinder Misfire Detected
16685 Cyl.1 Misfire Detected
16686 Cyl.2 Misfire Detected
16687 Cyl.3 Misfire Detected
16688 Cyl.4 Misfire Detected
16690 Cyl.6 Misfire Detected
19989 Cyl.5 Misfire Detected

And these are the only codes (besides my new intermitent immobilizer issue) I thought I had it fixed last year with several bottles of Techron, but they seem to still be there. Here is what I've done to solve:

1) All 6 coil packs replaced
2) New fuel pump (under recall) & filter
3) New plugs (installed by indy shop, NGK)
4) Air Filter(s)
5) Fixed Vac leak on front of motor (2)
6) Bunch of Techron

I would just watch them on the VAG as the accumulated to almost a hundred before resetting. But after all this, misfires were greatly reduced - they even went away completely after a while (so I though). Then, maybe a couple months later, I just realized that they were still there, it just wasn't enough to throw the CEL. Now they're getting back to the point where they throw the CEL again.

No one on the B6 boards seems to have this problem but me. Was wondering if anyone else with an A6 and the same motor has had similar problems. Worse is that I find out that my CAT(s) are ruined but I'm not trying to throw a bunch of cash into replacing parts just to have the same issue. I'm just going to start with some more bottles of Techron.

BTW I've always used at least 91 octane and full synthetic oil. The engine was very clean after checking the throttle body and valve covers.

JimmyC83

coolant temperature sensor malfunction? causing bad 02/fuel ratio?

shwndh

hard to change? This seems like a simple fix.

BTW, How would I test for this with VAG COM? I don't know how to really use this program to the full.

JimmyC83

no other related codes...that sucks i cant wait for this problem to hit too =(
we did it on gdawga4's car and should be on our cars by the spider hose at the top of back engine by the battery. its a PITA cause its under pressure from the coolant that flows over it, (have extra ready or distilled h20 in case it leaks) and its awkward being next to the frame to maneuver hands on the A4 mebbbee diff on our cars. maf sensor related maybe too ick this isnt going anywhere but in the direction of a check book...


i thought these people said 3.0's are bulletproof =P

GDawgA4

Do you have any hesitation when the car is cold when accelerating?

schnellmb

camshaft position sensor?

eCoastAudi

turned out to be a camshaft position sensor. They are only $30 each. You can disconnect them as well for a test and the engine will run.

DesmoTesta

Cyl 5 misfire, Dealer replaced all coilpacks as part of TSB

audikillsbmw

Luckily it was covered under CPO.<ul><li><a href="https://forums.audiworld.com/a6/msgs/750062.phtml">click</a></li></ul>

shwndh

None what-so-ever. Only the CEL and the small amount of mifires.