Modified A6 2014 drivability problems

[MikeBuono]

I need help. My Audi A6 2014 3.0T has stage 2 GIAC with single pulley and was installed in 2017 with 39,000 miles, now car has 71,000.
Recently I keep having stalling problems.
After parking and shut off it wouldn't restart, the next day started normally and ran fine. After scan they found no codes and no engine light. 3 weeks later same thing, ran rough then shut off and wouldn't restart , then next morning started normally but now engine light. Shop scanned an found PVC error, so replaced PVC oil separator and breather pipes and hose. 2 weeks later engine light comes on and scan found O2 sensor reading Bank 1 and 2 mixtures too rich, they replaced O2 sensors with Bosch and also MAP sensors. 3 weeks later cars starts running rough and stalls at traffic light and won't restart, next morning starts normal and runs fine with engine light on. I scan it and get Bank 1 and 2 mixtures too rich again. So I took it to Audi dealership and they claim using Bosch sensors and not Audi OEM is causing the problem. I'm not sure I believe that, but they reset and cleared engine light and car runs fine but I notice gas smell after turning off in my garage and see some black smoke from exhaust if accelerating hard from stop. I Still have same stalling issue as I did before spending 5,000.

[WideSuppie]

Either 2 problem. Cats or Fuel. Could be Fuel pump issues. HPFP if correct.

[halik008]

Either 2 problem. Cats or Fuel. Could be Fuel pump issues. HPFP if correct.

cats have nothing to do with AF ratio. Fuel/HPFP issues would cause lean not rich conditions.

[halik008]

I need help. My Audi A6 2014 3.0T has stage 2 GIAC with single pulley and was installed in 2017 with 39,000 miles, now car has 71,000.
Recently I keep having stalling problems.
After parking and shut off it wouldn't restart, the next day started normally and ran fine. After scan they found no codes and no engine light. 3 weeks later same thing, ran rough then shut off and wouldn't restart , then next morning started normally but now engine light. Shop scanned an found PVC error, so replaced PVC oil separator and breather pipes and hose. 2 weeks later engine light comes on and scan found O2 sensor reading Bank 1 and 2 mixtures too rich, they replaced O2 sensors with Bosch and also MAP sensors. 3 weeks later cars starts running rough and stalls at traffic light and won't restart, next morning starts normal and runs fine with engine light on. I scan it and get Bank 1 and 2 mixtures too rich again. So I took it to Audi dealership and they claim using Bosch sensors and not Audi OEM is causing the problem. I'm not sure I believe that, but they reset and cleared engine light and car runs fine but I notice gas smell after turning off in my garage and see some black smoke from exhaust if accelerating hard from stop. I Still have same stalling issue as I did before spending 5,000.

what do you mean wont restart? Cranks but will not fire up or?

[MikeBuono]

Yes cranks but won’t start, after a few hours start and runs normally. The stalling usually happens after driving more than 30 minutes

[Alabama]

Yes cranks but won’t start, after a few hours start and runs normally. The stalling usually happens after driving more than 30 minutes

Have you tried different gas station/fuel system cleaner (e.g., Redline SI-1 or equivalent)? Seems unlikely to work but cheap and easy enough to test.

[WatchMeSpend]

Sounds like it's running rich. Reminds me of my A4 when it got hot and thought it was cold because the ECT sensor wasn't working. It didn't stall, but you weren't going to start it when it was hot. Any chance to put it on an OBD while its running and watching it go sour? I'm thinking like with an HP Tuners connected to it you would see the parameters change as you drove before you had issues.

[f4m0u5]

have you checked you injectors?

i would check your fuel rail prssure right when you shut engine off, then wait 5 mins (without starting engine) and make sure it is higher and rising and did not drop.

if the fuel rail pressure dropped its a leaking fuel injector


BTW fuel injector will cause rich conditions, stalling and hard start problems

[A6sport]

Coolant temp sensor... the C7 does have one, right?

It's an old Audi fix for all symptoms OP described.

[MikeBuono]

Have you tried different gas station/fuel system cleaner (e.g., Redline SI-1 or equivalent)? Seems unlikely to work but cheap and easy enough to test.

Yes tried different gas stations and injector cleaning

[MikeBuono]

have you checked you injectors?

i would check your fuel rail prssure right when you shut engine off, then wait 5 mins (without starting engine) and make sure it is higher and rising and did not drop.

if the fuel rail pressure dropped its a leaking fuel injector


BTW fuel injector will cause rich conditions, stalling and hard start problems

It does feel like fuel issue. I notice decel popping in exhaust right before it runs rough and then stalls.
I heard O2 spacers might help.
But car ran great for 3 years without spacers after tune installation so it shouldn’t need them now.

[MikeBuono]

Coolant temp sensor... the C7 does have one, right?

It's an old Audi fix for all symptoms OP described.
I did have water pump and coolant sensor replaced last year.

[Audibellybutton]

I need help. My Audi A6 2014 3.0T has stage 2 GIAC with single pulley and was installed in 2017 with 39,000 miles, now car has 71,000.
Recently I keep having stalling problems.
After parking and shut off it wouldn't restart, the next day started normally and ran fine. After scan they found no codes and no engine light. 3 weeks later same thing, ran rough then shut off and wouldn't restart , then next morning started normally but now engine light. Shop scanned an found PVC error, so replaced PVC oil separator and breather pipes and hose. 2 weeks later engine light comes on and scan found O2 sensor reading Bank 1 and 2 mixtures too rich, they replaced O2 sensors with Bosch and also MAP sensors. 3 weeks later cars starts running rough and stalls at traffic light and won't restart, next morning starts normal and runs fine with engine light on. I scan it and get Bank 1 and 2 mixtures too rich again. So I took it to Audi dealership and they claim using Bosch sensors and not Audi OEM is causing the problem. I'm not sure I believe that, but they reset and cleared engine light and car runs fine but I notice gas smell after turning off in my garage and see some black smoke from exhaust if accelerating hard from stop. I Still have same stalling issue as I did before spending 5,000.

I wouldnt be taking your car to the dealership if you do not have a warranty..

the bosch o2 sensors should be fine.

from what you describe my guesses would be

-hpfp
-cats

do you have vcds? you can test your hpfp and cats i believe. Besides that, like somebody mentioned it could be a leaking injector

also are you smelling raw fuel? its a much different smell than a rich exhaust. If you are smelling raw fuel that definitely is a problem and I would inspect the injectors and the O rings for the injectors, make sure they are good, and none are missing...

[paul-g]

pull the plugs they should tell you everything you need to know about fuel and how it's running, if they ALL look good then you know you eliminated a few things. then the job gets harder

[ANMS4]

Just sounds like a "hot" start issue= HPFP leaking

[MikeBuono]

Just sounds like a "hot" start issue= HPFP leaking
Sorry to ask, but what is HPFP

[MikeBuono]

I wouldnt be taking your car to the dealership if you do not have a warranty..

the bosch o2 sensors should be fine.

from what you describe my guesses would be

-hpfp
-cats

do you have vcds? you can test your hpfp and cats i believe. Besides that, like somebody mentioned it could be a leaking injector

also are you smelling raw fuel? its a much different smell than a rich exhaust. If you are smelling raw fuel that definitely is a problem and I would inspect the injectors and the O rings for the injectors, make sure they are good, and none are missing...

Car is out of warranty.
Smells like rich exhaust not fuel.
I’ll have them check cats.

[Audibellybutton]

Car is out of warranty.
Smells like rich exhaust not fuel.
I’ll have them check cats.

if your cats are blown. which is very possible, your car will run rich and smell rich too
that however would not cause any stalling issues.

that part sounds like hpfp which is the high pressure fuel pump. you may also want to pop off your oil cap and see if your oil smells like fuel

[MikeBuono]

if your cats are blown. which is very possible, your car will run rich and smell rich too
that however would not cause any stalling issues.

that part sounds like hpfp which is the high pressure fuel pump. you may also want to pop off your oil cap and see if your oil smells like fuel

Yes it does smell like gas when I pulled oil cap. Interesting thing too, is I just drove the car for first time in 2 days and feels very responsive but came up to make slow right turn and nothing happened for 1-2 seconds when I hit throttle.
Car usually doesn’t experience rough idle or stalling until after driving 20-30 minutes.

[WideSuppie]

HPFP - High Pressure Fuel Pump

[ANMS4]

Sorry to ask, but what is HPFP

High pressure fuel pump. They will "leak'" and cause a hot start issue. I had it when I had my A6 I replaced them with performance ones for Loba. I'll have the same issue on my S8 at some point,

[ANMS4]

Yes it does smell like gas when I pulled oil cap. Interesting thing too, is I just drove the car for first time in 2 days and feels very responsive but came up to make slow right turn and nothing happened for 1-2 seconds when I hit throttle.
Car usually doesn’t experience rough idle or stalling until after driving 20-30 minutes.

The HPFP are leaking.

[Audibellybutton]

If you are going to replace your HPFP and don't want to spend an arm and a leg. I recommend going to rockauto.com and getting a HPFP for your 2014 A6 the prices range from $237 to $380

since you are modified I actually recommend you getting a new hpfp and/or adding the IE HPFP upgrade Kit if budget allows. Its a big improvement and running Ethanol will pick you up some power and cylinder cooling benefits

https://performancebyie.com/products/ie-3-0t-hpfp-internal-upgrade-kit-fits-audi-s4-s5-a6-a7-sq5-q5-supercharged-engines?_pos=1&_sid=7f85d073a&_ss=r

but its not necessary, just an idea since you are going to have the pump out already. Over all the HPFP replacement job is not difficult at all. Especially if you are just swapping out the pump with a new one.

[MikeBuono]

I ordered new HPFP, but the one I got doesn’t match what I have. So in the process of getting it replaced. Apparently there was a TSB HPFP replacement before I purchased the car

[MikeBuono]

I ordered new HPFP, but the one I got doesn’t match what I have. So in the process of getting it replaced. Apparently there was a TSB HPFP replacement before I purchased the car
https://www.audizine.com/gallery/data/500/medium/B3124A9A-5483-4398-9F51-A0ACD9BE289E.jpeg

[Alabama]

I ordered new HPFP, but the one I got doesn’t match what I have.

Maybe it's Bosch and not OEM?!

[f4m0u5]

Thats definitely not the correct hpfp for the 3.0t, it should not have a valve or w.e that black thing is on the end

[MikeBuono]

I did get correct HPFP Hitachi installed and rough idle and stalling is gone.
But I still have Code P112700 Bank 1&2 mixture adaptation system to rich.

[WideSuppie]

I did get correct HPFP Hitachi installed and rough idle and stalling is gone.
But I still have Code P112700 Bank 1&2 mixture adaptation system to rich.

Good to know that HPFP was the culprit. Have you change the plugs?

[MikeBuono]

Good to know that HPFP was the culprit. Have you change the plugs?
I changed plugs and coils 10,000 miles ago