spagolli94

The other night, I noticed intermittent sputtering/lurching/hesitation when gently accelerating at 35 mph in 3rd or 4th gear, didn't think much of it as it was very minor and went away as quickly as it showed up. But the next day, bigger issues began…

• Driving on long highway trip, going about 75mph steady.
• EPC and ESP lights came on, power was cut way down (flooring it does nothing)
• Pulled over, shut car off for a couple minutes
• When I started it again, warning lights turned off, car ran fine for 50 miles
• Then the EPC and ESP lights came on again, this time along with the check engine light, power was cut again
• I drove 50 miles like this, struggling to make it up hills, max speed was 75mph
• Stopped for gas, shut car off for a few minutes
• Started car again, check engine light was on, but EPC and ESP lights had gone off, power was back to normal
• Drove 100 miles like this, got home, let car sit overnight
• Started car in the morning, all lights were off, car was running fine.

Researched online, found possible issues for RS4's with identical symptoms
Intake Runner failure? (stuck flap or valve)
Intake Runner Sensor?
Mass Airflow Sensor?
O2 Sensor?
Throttle Body?
Accelerator Pedal Module?
Wiring Harness?

Has anybody else on this forum had similar issues? Going to call the dealer first thing in the morning...

fluevog

Could be any of the following you mentioned, other factors could be a vacuum leak, clogged fuel injectors ( run a bottle of Chevon Techron) or carbon buildup like this:

http://forums.quattroworld.com/rs4b7/msgs/52391.phtml

spagolli94

Thanks, I'll add those things for the list of stuff for the dealer to check out.

Winterrunner

YEah either Vacuum leak of Carbon buoldup are my two guesses....

silverRS4

Intake manifold flap implausible signal caused by faulty sensor and/or high levels of carbon buildup and/or vacuum leak.

spagolli94

I gave them a list of possible causes. They seemed offended by "junk you find on the internet." They said, we'll worry about fixing your car, not everybody elses. Okay, fine. So they plugged it in and ran the codes. It came back with something like "exceeded maximum torque limit" (or similar). They asked if I had been pushing it hard. Occasionally I do, after all this is an RS4 we're talking about. But at the time the warning lights popped up, I had been cruising at 75 or so for at least two hours.

Anyway, the lights were all off this morning and the car is running fine. They said it was a "sporadic error", cleared/reset the computer and to bring it back if it happens again. They said if it happens when I'm far from home on the highway (like it did the other day), I can simply get off the first exit, turn the car off and start it again to clear the EPC light and get full power back.

I did speak directly with the mechanic about carbon buildup. He said if it was related to that (or any other mechanical issue), you're car wouldn't be running fine right now. He said some RS4s do have carbon buildup, but typically it's very obvious when they do because they run like crap. On the way home from the dealer, I punched it a few times and I have to say my car is running very strong - smooth and powerful. No signs of anything wrong whatsoever.

So at this point, my car is running fine and I basically have my fingers crossed that it won't happen again. I almost wish they were able to find something concrete and fix it, for peace of mind.

slrkappa@yahoo.com

My 2016 A3 just did this tonight. I pulled over after hours of solid driving, restarted the car and everything has been good since.