Has anyone else had their S4 shut off randomly?

[chi123]

I was driving yesterday and was sitting in traffic when I noticed my car running a little rough and my P3 gauge going up to -15 when it's usually -20. The RPM didn't change and was around 800 RPM. I started driving and was in second gear when I tried to accelerate but nothing. The RPM wouldn't go up or anything when pressing the gas pedal. I put the car in neutral and was coasting for a second or two when the engine just died. I pulled over and started it up again and it ran fine. No CELs or warnings. Any ideas what this could have been or anyone experienced this before? Car has 131K and GIAC stage 2 tune. Never had a CEL in the 50K miles I've owned this car.

[gfro1234]

Hmm maybe some kind of intermittent leak in a vacuum hose/valve?

[chi123]

Hmm maybe some kind of intermittent leak in a vacuum hose/valve?

That's what I'm wondering too but figuring out which hose is the tough part lol.

[PopTart]

Welcome to the Mechatronic Failure group

[chi123]

Welcome to the Mechatronic Failure group

Forgot to mention, but my car is manual.

[Bartlett]

Have you done any logging?

[hilmar2k]

Mine shuts off every time I hit the start button instead of releasing the parking brake. I do it like 25% if the time. Stupid muscle memory.

[Ch13f]

I had this happen. Same issue and situation. The first time it happened was just as your situation. I stopped and restarted with no cel, warnings, etc. I let it go but then it happened again weeks later. This time I checked for faults with VCDS. Turns out I had over voltage faults. I ended replacing the voltage regulator. The brushes were very worn down. No problems since. (DSG)

[JBalls]

I had similar happen a couple times while doing basic maneuvers like reverse parking - car would essentially shut down for no rhyme or reason. Got car scanned, and found the car has thrown over voltage codes. My alternator had gone wrong. Replaced it and so far so good.

[chi123]

I had similar happen a couple times while doing basic maneuvers like reverse parking - car would essentially shut down for no rhyme or reason. Got car scanned, and found the car has thrown over voltage codes. My alternator had gone wrong. Replaced it and so far so good.

Hmm, so that's two people with voltage issues. I'll do some logging and see then. I hope it's not the alternator, I just replaced it with an OEM one less than a year ago just for preventative maintenance since I was at 125K on the original alternator.

[JBalls]

Hmm, so that's two people with voltage issues. I'll do some logging and see then. I hope it's not the alternator, I just replaced it with an OEM one less than a year ago just for preventative maintenance since I was at 125K on the original alternator.

For what it’s worth, my car tech said it was the specifically voltage regulator that went bad, but we went ahead and swapped the alternator as my car is 2010 (im the second owner) and I looked as it as preventative move against future electrical issues.

[Wreckm]

Has been happening to me for awhile now. At red lights i will notice idle jump and all electric is shut down. No dash lights radio ect. I have not tried pulling any logs when it happens.

[chi123]

Well I scanned my car and there were codes stored. One code was P0507 and another was showing short/open circuit for MAP sensor. So I ordered all three MAP sensors and will see what happens once I replace them.

[Pawan2013]

same thing happened to me, needed a new voltage regulator

[Wreckm]

same thing happened to me, needed a new voltage regulator

You guys just replacing voltage regulator or replacing entire alternator?

[Ch13f]

I replaced just the voltage regulator.

[audis4culver]

Yes. Same thing on my 2011 s4. voltage reg as it overloads the battery. its happened three times and I am able to see the battery get overloaded. for me specifically it ONLY has ever happened when the outside air temps are above 90 in the summer here in Atlanta. never happened under 90. my gut tells me heat impacts the battery and its sending info to the reg vice versa. I have not replaced my reg yet.. since mine is pretty predictable - dont drive above 90 degrees. also, never happened prior to my stage 2 tune. this must also somehow add another level of complexity to the system?