Darth Sidious

here is the little story that made my heart drop to the pit of my stomach.

friday morning i was on my was to work(~35mi trip) about half way i noticed the engine felt like it was hesitating, more like cutting out, then catching back up with it self to stay at 65mph. the speed never dropped or went over what the cruise was set at. i thought something was seriously wrong at this point and i wouldn't be making it to work and so on and so forth. well i happened to be near a gas station and pulled off the highway and up next to a pump. as i was pulling off the highway the CEL (which has been on and off since summer, figuring it maybe something to do with the turbos on their way out fouling the o2's) started to blink. so i knew i needed to pull over asap and shut the car off.

after going over a small check list of what it might be i came up with the engine wasn't getting enough fuel, i had just under 1/4 tank and it was down about 5degree or so the night before and the car is parked outside all night. so i put a few gallons in and waited a couple minutes and started it. i noticed an extra large cloud of smoke from the exhaust on the start up and thought "oh great there goes one or both of the turbos" so i popped the hood to see if i could hear anything that i haven't heard before and whatnot. nothing louder or new.

so i let it warm up a little more and and decided i had to get to work, if i could make it there i could probably take a company car home in the worst case scenario. car drove fine after having a little sip of 93 and warming up, CEL was still on but didn't start blinking at all the final 12-15mi of the trip.

well i was able to get it home but was still worried why the CEL was on and why the car was acting up in the morning. so luckly there is a fellow dubber/audi guy with vag com that lives about 5 blocks away. got in touch with him and went and scanned my car and came up with this:


12 Faults Found:
16805 - Warm Up Catalyst; Bank 1: Efficiency Below Threshold
P0421 - 35-10 - - - Intermittent
17539 - Oxygen (Lambda) Sensor; B2 S1: Internal Resistance too High
P1131 - 35-10 - - - Intermittent
17521 - Oxygen (Lambda) Sensor; B1 S1: Internal Resistance too High
P1113 - 35-10 - - - Intermittent
16538 - Oxygen (Lambda) Sensor B2 S1: No Activity
P0154 - 35-10 - - - Intermittent
16518 - Oxygen (Lambda) Sensor B1 S1: No Activity
P0134 - 35-10 - - - Intermittent
16684 - Random/Multiple Cylinder Misfire Detected
P0300 - 35-10 - - - Intermittent
16688 - Cylinder 4: Misfire Detected
P0304 - 35-10 - - - Intermittent
16690 - Cylinder 6: Misfire Detected
P0306 - 35-10 - - - Intermittent
16689 - Cylinder 5: Misfire Detected
P0305 - 35-10 - - - Intermittent
16685 - Cylinder 1: Misfire Detected
P0301 - 35-10 - - - Intermittent
16687 - Cylinder 3: Misfire Detected
P0303 - 35-10 - - - Intermittent
16686 - Cylinder 2: Misfire Detected
P0302 - 35-10 - - - Intermittent
Readiness: 0000 0000



we didn't have time to go and get any logs.

couple questions.

would the o2 fault codes be causing the misfires?
which o2 are those? are there 4 or 2 on our cars?
what blocks do i want to log when i can get in touch with a vag and have the time?
could the misfires be bad coils along with bad o2?

i cleared the faults friday night and have drove abour 30mi since then and the car has gotten up to temp and the CEL has no come back yet.

if you guys could share your wisdom with me so i can get smarter with troubleshooting and logging and get the S4 back up and running properly.

TIA
Tim

S4ptld

I'm not sure. Someone else will know though. Misfires could be faulty EGT sensors but more likely has to do with bad O2's. I'd start by replacing all.

Darth Sidious

but from the codes i pulled i figured i'd go ahead and replace all 4 and instead of replacing cats i'd just gut them and get the cel eliminator for it.

that seems like it would be a more penny effective approach.

i'm still searching for which blocks to log if possible. and maybe some other good ones to do to, like req boots vs. act. boost and what nots.

TIA again
Tim