Misfire started after using AC and shutting down...then cleared itself after 1/2 mile
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Good day fellow Audi enthusiasts!
I have a well running A4 and was performing my errands for the day. It was hot, so I fired up the A/C for the first time in a long time to enjoy some cold air and the engine seemed a bit more strained, as is expected. This was in local traffic mostly.
I pulled up, shut off the car and came back 1/2 hour later , restarted and all of a sudden, it felt like it was running on 3 cylinders. My fears were confirmed when check engine blinked on. I whipped out my star tester and read out p0304 "misfire on #4". It stayed misfiring for a while and through a few code resets and stops/starts and driving up and down the driveway.
I assembled my family and requisitioned a rescue car and we were in the process of limping it just "off idle" with the hazards on the 1/2 or maybe even 1/4 mile to the shop on the corner when it suddenly cleared out. I reset the codes. Didnt come back. Drove up and down a hill nearby. Didnt come back. Sent everyone home, drove around a bit. Still didnt come back.
Was this heat soak from the A/C? Was that just a coincidence? Clogged injector? Whats the usual culprit? Does the DI cassette do this thing when hot? I applied 2 bottles of fuel injector cleaner just to be safe.
Should I ignore and go on or is there some place I can poke around to verify what had happened?
I have a well running A4 and was performing my errands for the day. It was hot, so I fired up the A/C for the first time in a long time to enjoy some cold air and the engine seemed a bit more strained, as is expected. This was in local traffic mostly.
I pulled up, shut off the car and came back 1/2 hour later , restarted and all of a sudden, it felt like it was running on 3 cylinders. My fears were confirmed when check engine blinked on. I whipped out my star tester and read out p0304 "misfire on #4". It stayed misfiring for a while and through a few code resets and stops/starts and driving up and down the driveway.
I assembled my family and requisitioned a rescue car and we were in the process of limping it just "off idle" with the hazards on the 1/2 or maybe even 1/4 mile to the shop on the corner when it suddenly cleared out. I reset the codes. Didnt come back. Drove up and down a hill nearby. Didnt come back. Sent everyone home, drove around a bit. Still didnt come back.
Was this heat soak from the A/C? Was that just a coincidence? Clogged injector? Whats the usual culprit? Does the DI cassette do this thing when hot? I applied 2 bottles of fuel injector cleaner just to be safe.
Should I ignore and go on or is there some place I can poke around to verify what had happened?
Super Moderator
IMO before you freak out and start replacing stuff is a wait and see if it happens again, if it does what are the same factors that could of caused it to happen. If it doesn't come back then you're good to go!
My thinking exactly but my alternate thinking is.....if I use the AC again and it comes back and stays then I am out my daily commuter car =O
Misfires are bad. Clogged cats from the unignited mixture or just the engine shaking itself apart.
On my saab 9000, I know the failing Direct injection casette would act up when it was hot. The heat has to be the culprit, compounded by engine load from the AC. I've driven through the same conditions almost 2 weeks now without repeat incident.
Misfires are bad. Clogged cats from the unignited mixture or just the engine shaking itself apart.
On my saab 9000, I know the failing Direct injection casette would act up when it was hot. The heat has to be the culprit, compounded by engine load from the AC. I've driven through the same conditions almost 2 weeks now without repeat incident.
