EPC (Electronic Power Control) Light came on - APR Stage 2+ - Sputter/Shaking

[CapnToll]

Well here's another entry into the saga of my '14 S5 with APR Stage 2+. Car's been running amazing, especially in the colder weather.

However, today on the way home from work the EPC light came on, the car shook really violently (couldn't really tell if it was coming from the rear or the front) and started coughing. I pulled over, turned it off and back on - seemed to finally idle okay and I nursed it home with no other incidents, except the light is still on. Everything looks fine under the hood (intake connections all good, that one intake vacuum is on fine).

Not sure if the brake pad wear indicator can trip the EPC, but my brakes started to squeal a couple days ago (about 4000 miles on the car now). Also of note, I had floored the car through 2 gears about 30 seconds before the light went on and had also come to a slow squealing stop. Note the brake pad indicator light is NOT on.

After I restarted, the transmission seemed fine in 'D' and Manual paddle shift mode.

Car Manual says:
"The EPC warning/indicator light (Electronic Power Control) illuminates when you switch the ignition on as a function check."

"If this warning/indicator light illuminates while you are driving, then there is a malfunction in the engine electronics. Have the malfunction corrected as soon as possible by your authorized Audi dealer or qualified repair facility."

Has anybody heard of this?? Trying not to freak out.....I called APR - they said they'd need the code so I will have to take it down to my APR dealer which is about 30 miles away. I'm thinking I should maybe get it towed down there. More vacation days down the drain it looks like...

Ugh...

[SpfldS4]

Check your spark plugs first and ignition coil's. Maybe the cars running a little rich and fouled the plugs

[CapnToll]

Check your spark plugs first and ignition coil's. Maybe the cars running a little rich and fouled the plugs

Good idea - I know it runs severely rich on the tune. With all my performance testing it might have fouled them. Just not sure if I want to touch anything yet (APR might want things checked a certain way or in a certain order without me meddling if I get free troubleshooting from them and my dealer....same with the dealership if I have to go to them)....not that it would be very noticeable if I just pulled the plugs to look.

[Amorphic]

Where's swank when you need him. I'd love to see his response to this.

[CapnToll]

My buddy has a scanner so hopefully he can come by tonight and see if we can pull something.

[drob23]

Need vcds tool

[CapnToll]

Need vcds tool

I guess for anything other than CEL hey....or do you even need VCDS to pull an engine light code

[tgsweat]

Where's swank when you need him. I'd love to see his response to this.

+1 i swear these were my exact words after reading this

[drob23]

I guess for anything other than CEL hey....or do you even need VCDS to pull an engine light code

Vcds will give you detailed breakdown and allow you to clear codes. Not to mention log various signals internal to the ECM.

[CapnToll]

Vcds will give you detailed breakdown and allow you to clear codes. Not to mention log various signals internal to the ECM.

Right, but a standard scanner should at least be able to pull the code just to make sure it's nothing that's about to grenade the engine.

[chaos2984]

If its a misfire code P0301-306 then whatever cyl is misfiring just move the coil first to another cyl and see if the misfire moves if not swap the plugs and see if it moves. If it moves with either whatever you did then you need to replace whats bad that you moved. Also if the misfire doesn't move when you move the coil and plug then you have a serious issue with that cylinder.

But from what you said you weren't beating on it so i doubt its anything serious of engine internal problem. Probably going to be something bolt on to the engine.

[gendry]

+2.

Swank, if you are reading this from the fire filled pits the great lords have seen fit to cast you down into, please consider creating a new account. You can use the moniker "notwestwestorswank" and then nobody will suspect you being a second account of yourself or that westwest character who was cast down for rather less political reasons.

+1 i swear these were my exact words after reading this

[CapnToll]

If its a misfire code P0301-306 then whatever cyl is misfiring just move the coil first to another cyl and see if the misfire moves if not swap the plugs and see if it moves. If it moves with either whatever you did then you need to replace whats bad that you moved. Also if the misfire doesn't move when you move the coil and plug then you have a serious issue with that cylinder.

But from what you said you weren't beating on it so i doubt its anything serious of engine internal problem. Probably going to be something bolt on to the engine.

I'm newish to Audis now, but wouldn't a misfire show up in an actual Check Engine Light rather than the EPC? Or is it if things are screwy, various module indicators could show up?

Thanks for the troubleshooting tips. So far my APR dealer has been happy to do all the trouble shooting free of charge, so if that's still the case I'd be more than happy for them to chase a misfire rather than do it in my cold, poorly lit garage :p. I've had a Honda project for years, I've bent over a hood in dark cold places enough lol

[saxon]

codes first

flash to stock to see if its tune related

[CapnToll]

codes first

flash to stock to see if its tune related

Yes that's for sure if it's not an obvious issue. Also if it is fouled plugs causing a misfire it could end up being an intermittent problem. When the car starting shaking I thought maybe I had a destroyed tire which could be a similar feeling to a terrible misfire

[John@Roc-Euro]

Could be as simple as a bad coilpack. Any tune will bring that to light faster than the stock software. Misfire/multiple random misfire would be the expected codes.

A common VW/Audi group thing.

[CapnToll]

Here's hoping it's simple.

[Jones2012s4]

Sounds like misfires and then disabling of the cylinders.

Restarting car resets it, EPC light will stay on.

Has happened to me before when testing meth spray, after a hard 3-4-5 pull the car suddenly felt like the motor was unbalanced, loss of power, and no go on the throttle.

I know why it happened to me though, question is, what caused yours.

[CapnToll]

Sounds like misfires and then disabling of the cylinders.

Restarting car resets it, EPC light will stay on.

Has happened to me before when testing meth spray, after a hard 3-4-5 pull the car suddenly felt like the motor was unbalanced, loss of power, and no go on the throttle.

I know why it happened to me though, question is, what caused yours.

Just started the car up - light is gone. Will drive her nice and easy to work tomorrow and see if it comes back. If it stays off I'll drive it a bit harder and see how she goes.

The only difference in the last few days is that the DA has dropped a couple thousand feet in the mornings and the car has been noticeably faster. I've kept the 93 tune strictly running 94 octane though so more power shouldn't be causing the engine to hiccup. DA was back up to 3500' when this happened though (also about 1 mile since a 90% gas tank fill from a few hours before).

[Intrepid One]

I know these lights coming on, especially after doing a tune freak us out..I think one key is to allow it to sit and perhaps reset itself..As a wise man once told me "Panic Slowly"...Hope everything stays ok for you..S

[Jones2012s4]

Just started the car up - light is gone. Will drive her nice and easy to work tomorrow and see if it comes back. If it stays off I'll drive it a bit harder and see how she goes.

The only difference in the last few days is that the DA has dropped a couple thousand feet in the mornings and the car has been noticeably faster. I've kept the 93 tune strictly running 94 octane though so more power shouldn't be causing the engine to hiccup. DA was back up to 3500' when this happened though (also about 1 mile since a 90% gas tank fill from a few hours before).

Possible that the light could clear itself, the fault will still be logged and can be read using VCDS. I cleared mine right away after stopping as luckily I had my laptop with me, maybe I cleared it before the light went off on its own.

[CapnToll]

Yes, I'll definitely get myself down to my APR dealer to log the code in memory. If the misfire was due to a fouled plug or plugs it could definitely creep up again. Perhaps a chunk of built-up carbon loosened and went through the combustion system causing a misfire and the car to freak out a little bit. I'll have to pull all the plugs - if they look anything more than what 6,000 km should look like I'll have to keep an eye on them regularly due to the richness of the tune (and how often I'm at WOT :p).

Everything seemed fine on the drive in to work this morning, so on the last off-ramp I gave her all she's got and it was nice and smooth in the crisp 25ºF air (DA finally dipped to just over 2000 feet).

[BoostEasy]

If you really only have 4k miles, I doubt it's your plugs but it could be any number of bad parts- or something transient. Were you flooring it before the oil temp was all the way up?

[CapnToll]

If you really only have 4k miles, I doubt it's your plugs but it could be any number of bad parts- or something transient. Were you flooring it before the oil temp was all the way up?

Nope, never drive it hard before temps are at normal operating levels. AFR is in the 10:1 range at WOT - so it's definitely rich. However, the burn seems to be pretty complete because I don't belch any black smoke. In comparison, two GIAC cars at the dyno who were running leaner than my car were blowing out a fair amount of black smoke.

[BoostEasy]

Nope, never drive it hard before temps are at normal operating levels. AFR is in the 10:1 range at WOT - so it's definitely rich. However, the burn seems to be pretty complete because I don't belch any black smoke. In comparison, two GIAC cars at the dyno who were running leaner than my car were blowing out a fair amount of black smoke.

You can only see water temp on the dash gauge and oil temp will lag it by quite a bit. Historically speaking, in 20-35'F cold weather it used to take my BMW 335 about a 10min drive to warm the oil to 180'F +. The JB4 I had on it wouldn't raise boost over stock until oil temp read via CAN bus was past about 160'F IIRC. In it's case, it was more to protect the turbo but also for the engine. It was noticeable once the OT hit 160'f as suddenly the car would wake right up and let you know the tune was rocking.

The thought is if you mashed it before the oil was fully warmed up, it could have possibly caused the cam adjusters to act a little strange. It's far fetched and more likely something else, just a thought I had.

[CapnToll]

Yea I've never tried to push the motor with the water temp gauge on the low side - I know in my G37, it would short shift like crazy until the water temp was up - not sure if it had a built-in safety like that for the oil temp. Yesterday my oil temp was most probably fine when I was driving as I had been driving for a while, parked at work for a short time, then drove it again for about 10 minutes. I think it was around 50ºF or so outside.

[SpfldS4]

What are you using to measure AFR? I think my Stage 2+ is running rich as well.

[CapnToll]

Tailpipe probe at the dyno

[Infra]

I've had this happen to me 3 times, always when the car is cold, in the morning, and I pull away immediately after starting up. Letting the car sit for a minute seems to prevent the problem. My dealer scanned codes and just saw a misfire, and wasn't real concerned. Seems to be a rather common thing.

[El Romano]

This happened to me a couple weeks ago, although I am just over 40k mi... definitely felt like a cylinder shut off. BMWs have done this for years, when a misfire is detected to prevent unburnt fuel from damaging the catalytic converters. Audi started recently, and is easily reset by cycling the ignition.

Well, I decided to check the spark plugs due to a P306 stored from this event. I was not surprised to see that all plugs were around .040 gapped, worn a bit, I would say from nearly 40k miles of being tuned along with many "spirited" driving sessions :D I replaced with NGK laser platinums gapped to .028 or thereabouts and hasn't happened again. Also I would have to say that the idle, especially when cold, is much much smoother. ..

Question: when you got tuned, did they replace or mess with your plugs at all?

Ad

[CapnToll]

No, my plugs weren't touched. I got tuned at about 1500 miles on the car so we weren't too concerned about restoring anything. My idle is a bit rough on the tune, so I might go that route whenever the plugs actually need replacement (nothing like the lopey idle from the big cams I have on my Honda, just feels like it pings a tad when it's just sitting).

It felt like a cylinder shut off because the engine balance was way off. I initially thought the rear diff turned into shrapnel because it was such a violent event and car was jerking like crazy for about 20-30 feet.

[dux ducis]

I just experienced the same thing and I recently got an APR Stage II tune. During a high rev shift from 1-2, right after the exhaust fart the EPC light came on. Needless to say I hobbled home with my tail between my legs.

Was this ever resolved? Trying my best to panic slowly.

[CapnToll]

Haven't seen this again since I restarted the car 1.5 years ago :)

[Swat413]

My EPC light came on with the warning, "Do not Exceed maximum engine speed of 4K RPMs". Brought it to the dealer and they said it was the oil pressure switch, which was fixed under warranty. I haven't driven the car yet to confirm.

[beckmaster]

had a similar problem, bank 4. For me it occurred the first time right after I finished a few track laps and switched the car from dynamic to comfort. Car started rattling like crazy. Shut off and restart and it went away. It repeated again the next day right after a several track sessions and going into comfort. Then a few days later after sitting in a parking lot after a minor spirited drive around town.

Answer: I was leaking coolant from a weld seam into cylinder 4. Audi had the part in stock and replaced it. Looking at pictures, cylinder 4 did not have a shred of carbon on it. it was as clean as the day I got it. The rest had some minor carbon deposits as expected. Going to the track again next month, wish me luck :)

[zachzdmme]

had a similar problem, bank 4. For me it occurred the first time right after I finished a few track laps and switched the car from dynamic to comfort. Car started rattling like crazy. Shut off and restart and it went away. It repeated again the next day right after a several track sessions and going into comfort. Then a few days later after sitting in a parking lot after a minor spirited drive around town.

Answer: I was leaking coolant from a weld seam into cylinder 4. Audi had the part in stock and replaced it. Looking at pictures, cylinder 4 did not have a shred of carbon on it. it was as clean as the day I got it. The rest had some minor carbon deposits as expected. Going to the track again next month, wish me luck :)

My car is a 2011 S4 with 105K miles and it's currently in the shop with similar symptoms. After a spirited drive the EPC light came on and engine started sputtering while attempting to accelerate. Check engine light flashes and car goes into limp mode limiting throttle.

The first diagnosis was my bank two manifold intake collapsed and my cylinder 6 has been misfiring, and I would need a new inter cooler. Also, he said my car had been leaking coolant (of absolutely no knowledge to me, never saw a light or the temp gauge fluctuate.) Apparently the coolant leaked into my exhaust furthering the damage. AFTER FIXING ALL THIS and changing the spark plugs car still has all the same problems. Drives normally at first, then under a heavy load it starts sputtering, and wants to shutoff and EPC light flashes.

Any ideas / suggestion guys???


Sent from my iPhone using Tapatalk

[S4'ed]

Sounds like your mechanic doesn't have a clue : "manifold intake collapsed" = BS, Leaking coolant "into"?? your exhaust????, and why do you need a new intercooler???

[CapnToll]

Happened again to me today shortly after I had fun in a corner where torque vectoring definitely was active.

Took two cycles of the ignition on/off for the light to go away and for the car to stop feeling like I was driving over train tracks. Hmm.

[Acejam]

This happened to me once after washing my car. I used my pressure washer and must've gotten some water into a crevice somewhere, resulting in water in my intake and/or near plugs. I simply restarted the car and the light went away, but it also ran rough.

Have you washed your car recently?

[CapnToll]

No I haven't. Light came back this evening along with the check engine light. The EPC light has since gone away but the check engine light doesn't seem to be going anywhere.


Sent from my iPad using Tapatalk