2013 Audi A4, Intermittent misfire that has occurred since I bought the car, info?

[Popperoni]

Hello All,

I was finally able to get my hands on a VCDS cable, after recently replacing a leaking fuel injector on cylinder 3 I figured I would run some tests to make sure I did it right and everything was good. After doing some logging, I noticed that every 3-5 minutes at idle, the car will misfire. It is typically cylinder 1 or 2 when it happens at idle. It never happens enough to trigger a CEL or anything, the only way I am able to tell is by the slight vibration the car makes. This has been ongoing since the night I bought the car. I never knew what that slight half-second vibration was until now, being that the data shows it. When the engine is cold and in low gears, cylinder 4 will once in a great while misfire, I can't even feel it, the logging software captured it.

For some reason, I cannot upload my text documents so I will just paste the text in here. I cut down most of the unimportant stuff, I know I have a brake malfunction and radio malfunction (just a Sirius XM controller), but I find it hard to believe that those could be an issue regarding this, I'll save that for a different post.

Sunday,18,April,2021,12:43:44:46821
VCDS -- Windows Based VAG/VAS Emulator Running on Windows 10 x64
VCDS Version: 21.3.0.0 (x64)  HEX-V2 CB: 0.4543.4
Data version: 20210226 DS325.0
www.Ross-Tech.com


VIN: WAUFFAFL3DN039297   License Plate:
Mileage: 129450km-80436mi   Repair Order:



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Chassis Type: FL-AU48 (8R0)
Scan: 01 02 03 05 08 09 15 16 17 19 2E 36 42 44 46 47 52 53 56 62
          72 77

VIN: WAUFFAFL3DN039297   Mileage: 129450km-80436miles

01-Engine -- Status: OK 0000
02-Auto Trans -- Status: OK 0000
03-ABS Brakes -- Status: Malfunction 0010
04-Steering Angle -- Status: OK 0000
05-Acc/Start Auth. -- Status: OK 0000
08-Auto HVAC -- Status: OK 0000
09-Cent. Elect. -- Status: OK 0000
15-Airbags -- Status: OK 0000
16-Steering wheel -- Status: OK 0000
17-Instruments -- Status: OK 0000
19-CAN Gateway -- Status: OK 0000
2E-Media Player 3 -- Status: OK 0000
36-Seat Mem. Drvr -- Status: OK 0000
42-Door Elect, Driver -- Status: OK 0000
44-Steering Assist -- Status: OK 0000
46-Central Conv. -- Status: OK 0000
47-Sound System -- Status: OK 0000
52-Door Elect, Pass. -- Status: OK 0000
53-Parking Brake -- Status: Malfunction 0010
56-Radio -- Status: Malfunction 0010
62-Door, Rear Left -- Status: OK 0000
72-Door, Rear Right -- Status: OK 0000
77-Telephone -- Status: OK 0000
-------------------------------------------------------------------------------
Address 01: Engine (DET-CPMA)       Labels:. 06H-907-115-CDN.clb
   Part No SW: 8K5 907 115 F    HW: 8K2 907 115 L
   Component: 2.0l R4/4V TF H09 0008 
   Revision: ECH09---   
   Coding: 4A2A0013242600062000
   Shop #: WSC 29043 001 1048576
   ASAM Dataset: EV_ECM20TFS0118K5907115F 001009
   ROD: EV_ECM20TFS0118K5907115F.rod
   VCID: 35372B00C5CA18F36C5-8060

No fault code found.
Readiness: 0000 0000

And here is a snippet of the engine misfires.

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                Address 01: Engine  (8K5 907 115 F)

11:47:23
  IDE00021   Engine RPM 759 /min
  IDE00075   Vehicle speed 0 km/h
  IDE00090-ENG57549   selected gear-Bits 0-7 0
  IDE00100   Engine torque 26.5 Nm
  IDE01975   Numb.of misfir.: cylinder 1 5111
  IDE01976   Numb.of misfir.: cylinder 2 5913
  IDE01977   Numb.of misfir.: cylinder 3 3518
  IDE01978   Numb.of misfir.: cylinder 4 1457

I am also attaching the log file, via google docs. I highlighted the misfire points.

https://drive.google.com/file/d/1ail...ew?usp=sharing

So, I have two questions.

1, Is it common to have this many misfires on an engine with 80k miles? Am I being overzealous?

2, This has been ongoing since I bought the car when I am driving the car at highway speeds, up to 6k RPM, not a peep from the cylinders. It seems only apparent when the engine is either cold or at low RPM. (see google sheets to see what I mean), do you have any idea what could be causing this?

I always figured that if an engine is misfiring, do not drive it. So the number of misfires from the log kinda scare me, as I have owned this car for 6 months and have been driving it regularly. I am ruling out fuel injectors and spark plugs, as I just changed all of that 250-300 miles ago, and the power and fuel economy is perfectly within spec. The car literally drives fine, had I not logged on VCDS I would have had no idea that the engine was misfiring.

Thank you, I really appreciate it.

 

[Uwe]

Hi and welcome.

Occasional misfires at low load with a cold engine are considered acceptable. I think the counters you're looking at are an ever increasing total. It's possible they would be cleared when you clear faults, but I'm not certain about that.

I think you should look at IDE01775 - IDE01778, which are "Misfires per 1000" revolutions for each of the cylinders.

I would also look at the fuel trims:
IDE00597-ENG167462 -- Long term adaptation of mixture formation bank 1
IDE00604-ENG167462 -- Short term adaptation of mixture formation bank 1

-Uwe-

 

[Popperoni]

Thank you for the reply, I was using the "Misfires per 1000", it shows it on that google sheets attachment, it's really helpful for knowing exactly when the misfire happens. I however did not know about the fuel trims, if that data is showing odd numbers, what would that point to? a fuel pump? Sorry, I am pretty much a newbie when it comes to car mechanics, this car is the first car I have ever worked on hah...

Also, are those totals for my cylinders an okay amount? Should I be concerned? Do all engines on average end up misfiring that much throughout their life? I know that's almost an impossible question to answer but you seem like you know your shit and have probably seen this before.

Thanks again, sir.

 

[Zenerdiode]

2, ...do you have any idea what could be causing this?

Carbon build-up on the back of the intake valves is a known problem on pretty much all Direct Injection gasoline engines, that will cause lumpy misfires at idle. So much so, VAG now use extra injectors in the ports to keep the valves clean.

 

[Uwe]

VAG now use extra injectors in the ports to keep the valves clean.

Only in some markets and NAR isn't one of them.

-Uwe-

 

[Jetta 97]

Carbon build-up on the back of the intake valves is a known problem on pretty much all Direct Injection gasoline engines, that will cause lumpy misfires at idle. So much so, VAG now use extra injectors in the ports to keep the valves clean.

Agree 100% with this .
It is Not VAG injector problem, it is people,Do not get me wrong on this , not saying anything to OP, just in general.

First this is This car MUST USE 93 Octane Fuel all the time, NOT USE 87 EVER.
Second thing is , it is TURBO Engine , So Drive it like turbo engine, Push it , not like Old Mk2 DIESEL .

 

[Popperoni]

Agree 100% with this .
It is Not VAG injector problem, it is people,Do not get me wrong on this , not saying anything to OP, just in general.

First this is This car MUST USE 93 Octane Fuel all the time, NOT USE 87 EVER.
Second thing is , it is TURBO Engine , So Drive it like turbo engine, Push it , not like Old Mk2 DIESEL .

Carbon build-up on the back of the intake valves is a known problem on pretty much all Direct Injection gasoline engines, that will cause lumpy misfires at idle. So much so, VAG now use extra injectors in the ports to keep the valves clean.

Thank you guys for the replies. Yeah, when I was replacing my fuel injectors I took a peek at the valves and they weren't too bad. I mean, they were black as all hell, but I did not see clumps of carbon, and being that I am so new at doing any kind of repairs on a car, (on top of never owning a DFI car in my life, coming from a 2002 malibu that required 0 maintenance, hah) I figured when it got near 100k miles I would take it into a shop to get a carbon cleaning, new transmission fluid, yadda yadda. But now after seeing these replies that is probably all it is, being the misfires are "type C" and are not affecting my use of the car in any way. I will probably schedule that to get done in the next week or two and post back if the problem persists.

Also, Jetta 97, is 91 octane okay to use? Where I live it's all I have, and Audi says it's the minimum recommended so I figured it would be alright. Also, does E85 cause more build-up? or less? I'm not going to use E85, but I am curious.

 

[Jetta 97]

Thank you guys for the replies. Yeah, when I was replacing my fuel injectors I took a peek at the valves and they weren't too bad. I mean, they were black as all hell, but I did not see clumps of carbon, and being that I am so new at doing any kind of repairs on a car, (on top of never owning a DFI car in my life, coming from a 2002 malibu that required 0 maintenance, hah) I figured when it got near 100k miles I would take it into a shop to get a carbon cleaning, new transmission fluid, yadda yadda. But now after seeing these replies that is probably all it is, being the misfires are "type C" and are not affecting my use of the car in any way. I will probably schedule that to get done in the next week or two and post back if the problem persists.

Also, Jetta 97, is 91 octane okay to use? Where I live it's all I have, and Audi says it's the minimum recommended so I figured it would be alright. Also, does E85 cause more build-up? or less? I'm not going to use E85, but I am curious.

Yes 91 is Ok as well. I really do not know about E85.

 

[PetrolDave]

Also, does E85 cause more build-up? or less? I'm not going to use E85, but I am curious.

Nt sure about the carbon build-up with E85 but it does need completely different engine mapping since the calorific value of E85 is so different from regular gasoline which requires significantly different injection timings and volumes. The automotive consultancy I used to work for did some E85 mapping work for cars sold in Brazil and we had a special E85 gas pump in the engineering yard.

BTW in Europe most gasoline is actually E5 and it is planned to make it E10 very soon.

 

[Uwe]

BTW in Europe most gasline is actually E5 and it is planned to make it E10 very soon.

US "gasoline" is almost universally E10. The US automakers did produce quite a few "flex fuel" vehicles that will run on anything from straight gasoline to E85, so E85 and Exx blends are available at some filling stations.

-Uwe-

 

[Popperoni]

Actually what's funny is nearly all of the stations around me also have 91 recreational fuel (0 ethonol) and late nights when nobody is around I will sometimes fill it with that, haha. Don't know if straight 91 hurts my engine but I don't see why it would. I just know it's not the most legal thing to do.

 

[Uwe]

Don't know if straight 91 hurts my engine but I don't see why it would. I just know it's not the most legal thing to do.

I don't see why it would hurt anything, or even why it would be illegal. Non-ethanol gasoline is more readily available in rural areas than urban or suburban, but it tends to be more expensive that E10 of the same octane. I use it when I can find it, provided it meets the octane spec of the vehicle I'm driving.

Some years ago, I filled our 2.8L 24V VR6 Eurovan with 93 octane ethanol-free. Toward the end of that tank, I checked the fuel trims, then re-filled with E10 and watched them in real-time. There was a noticeable (several percent) change in the trims going back to E10.

-Uwe-