# Backfire under full throttle then EPC light -2016 GTI



## Mike24VR6 (Mar 21, 2014)

So I was driving last week and I was merging onto a highway and I took 2nd gear and stepped on it hit about 4000 rpms in full boost and car backfired and stuttered/hesitated a little bit then I grabbed 3rd gear at about 3000 rpms and then I stepped on it about 90% throttle and my car backfired maybe 5 times in 1 second. All of a sudden the EPC light started flashing and I immediately pulled over turned the car off for about a minute and turned it back on EPC light was off. Ever since then if im ever going wide open throttle I always back off the throttle when it starts backfiring so it doesn't come on again. 

I'm thinking of buying an OBDEleven and an android tablet and monitor as it happens maybe I'll be able to pull a code or something from the EPC light since the check engine light doesn't come on. Weird things have been going on with my MK7 since the day I've bought it. It's not the first time the EPC light came on. It happened when the car was bone stock at about 1200 miles and I brought it to a dealer a little bit after and they said it's probably "just a glitch". I'm starting to think it's much more than "just a glitch". I've never been able to take the car up to redline because of it. I'm at a loss of options.


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## _Riddle (Oct 16, 2015)

Take it to the dealer and replicate the issue with a technician in the car. It's under warranty, they should fix it. If they give you push back, escalate the issue to VWoA.


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## PowerslavePA (Dec 9, 2014)

There are two main causes for backfires, besides a bad valve spring....

One, means an exhaust valve was open at detonation. This is a 
timing issue. These engines use VVT, which will advance or retard based
on what the knock sensors "hear."

The more towards WOT you go, the more the timing wants to advance, unless
knock is detected, then it will retard the timing. 

Two, the fuel was not detonated, and it went out the exhaust stroke and detonated
in the hot exhaust. This could be a coil pack or plug issue, one or some cannot keep up
with the RPMs.

If you are due for a plug change, may as well just do it, and coil packs if you can,
and get that out of the way. If it happens after, then it's a timing issue, but can
be a weak exhaust valve spring, at high RPMs, it doesn't close all the way at
those times.

There are a lot of potential causes...


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## Mike24VR6 (Mar 21, 2014)

Well at 14,000 miles neither should be a problem. I’m going to swap the ignition coil to another cylinder then see if the misfire moves and if that doesn’t change, I’ll be changing the spark plug in cylinder 2(where the problem is) to a different cylinder and if that doesn’t work. I’ll take it to a dealership. 

On another note, My brother is constantly warning me about taking my gti to the dealership. He thinks they will make the problem worse or another problem will come out of the blue. Although I’ve heard things about dealers messing up bad with cars, I think he might be overdramatic. Like the takata airbag thing, my mom has a honda crv and its one of the many recalled vehicles for the airbag and he’s refusing to let her go get the airbag swapped because he thinks they’re going to mess with it in some way. What do you guys think about this?


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## PowerslavePA (Dec 9, 2014)

The mechanics at the VW dealers, for the most part, are NOT actually familiar or experts with 
the product. They're just SAE certified technicians that can read a service manual...

If your warranty is still in tact, I would not bother doing anything except taking it to the dealer. 
I would not even mess with it, because if you DO, they can say YOU caused the problem, and
they have done it, to ME! Mine was even more simpler. Two of my tail lights were damaged,
and I showed them, and they told me that they would find me replacements. After 4 months?
I went in, and wanted them, they said I damaged them putting LEDs in them. They were
total jag-offs. So, if they'll blame you for breaking your tails by putting LEDs in, imagine what
they would tell you if you did that work, and they can see it. They will blame you for the
the problem.

The issue was nothing major either, just some plastic that can be removed, one
was off, and the driver side outer tail, the rubber seal on the right side is on a
plastic piece that can come off, was broken. There is another plastic piece on the
trunk lid tails, like a plastic cap that comes off, one was missing; but I did it when
I put the LEDs in... They totally went back on their word, and blamed me for
the damages.


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## Mike24VR6 (Mar 21, 2014)

Interesting, it seems like they’ll blame anything/anyone to not work on our car.

On another note, I went to my old mechanic and he pulled a few codes and one of them was the cylinder 2 misfire code, the other one was a “hide cylinder” code (excessive misfire). There was also a P0441 code, in which he says I should take it to the dealer because it’ll cost me a lot in the long run along with the misfire code and that it’ll give me a problem when inspection time comes around. He says New Jersey inspection will find the code and won’t pass the car. By the way, that is the “Evap Emission Control System Incorrect Purge Flow” code.

So that being said, I went to the dealership right after the lady there says “for the P0441 code, it might’ve been a loose gas cap or an N80 valve.” I also told them about the misfire code and explained the whole backfire-EPC light situation she said “it could be that the software of the ECM is outdated and it just needs an update. But we can’t say anything for sure until we look at it.” She asked me if I had any mods and I said “intake”. But I have a bov, turbo muffler delete and a straight pipe as well. 

When I told them that I had my mechanic scan the car and pulled the codes they were somewhat shocked. In the corner of my eye, I saw the lady give another employee (who might’ve been a service tech) “the look”. 
Ya know...... The “This-guy-definitely-has-tuner-fast&furious-boyracer-mods. Lets-void-the-****-out-of-his warranty-and-blame-the-misfire-on-his-intake” look. I felt like I was in an interrogation scene and I unknowingly spilt self-incriminating evidence to the detectives. But these weren’t detectives, they were service consultants.

So anyway, appointments made for Monday. Today is the only day in my life I will say I can’t wait until Monday. I guess it feels good not having to pay out of pocket for this. Damn diagnostics without warranty was $125. 











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## Mike24VR6 (Mar 21, 2014)

I just got a call from the dealer and they said that “its a sporadic misfire” so its not always on. 

Get ready for this...... 

The tech is blaming my intake.

So I explained to them that it happened when the car was bone stock at 1200 miles. They said they’ll take it for a test drive later today. I told em I will go in there and recreate the issue with the tech on a test drive tomorrow. I will keep you guys posted.


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## Mike24VR6 (Mar 21, 2014)

I just went to the dealer and talked to the service tech and he said he’s going to swap the coils and if that doesn’t work he said he’s calling VW of America and he’s sending them datalogs of the car also to make sure it isnt tuned, but I didnt tune it. Apparently they might put a red flag on my car saying its modified so it’ll void my warranty. Im 99% sure its the ignition coil. They wanted my stock airbox back to see if it was the intake so I brought it back to them. Lets see what happens next


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## Mike24VR6 (Mar 21, 2014)

They just called and said there indeed was a faulty ignition coil. Im going to pick up the car now. I will update you guys if theres a charge or fee


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## Mike24VR6 (Mar 21, 2014)

They just called and said there indeed was a faulty ignition coil. Im going to pick up the car now. I will update you guys if theres a charge or fee


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## Mike24VR6 (Mar 21, 2014)

Ignition coil was at fault. It was free and they gave me a complementary car wash as well. Case closed.


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