RS7 Cylinder 5 misfire

[mariokart]

I’m a stage 1 and last night at 125mph a Check Engine came up and read Cyl 5 misfire. I have seen others mention cyl 5. What causes this? What’s the remedy? Where in the motor is cyl 5?


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[allenzhang215]

I'm assuming the car was warmed up completely. Did you re-gap the spark plug to APR recommended size?

[mariokart]

I'm assuming the car was warmed up completely. Did you re-gap the spark plug to APR recommended size?

It was warm, I had been driving for 1/2 hour.
Do you know the gapping?


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[allenzhang215]

It was warm, I had been driving for 1/2 hour.
Do you know the gapping?


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APR recommends a spark plug gap of .024" +/- .002" for best results.

I had Cyl 5 misfire twice since I have the tune installed. One time just like you, when the car was warmed up, doing 90 on the highway.
The shop told me to re-gap the spark plug or running 91 map since it's freezing in michigan.

[mariokart]

APR recommends a spark plug gap of .024" +/- .002" for best results.

I had Cyl 5 misfire twice since I have the tune installed. One time just like you, when the car was warmed up, doing 90 on the highway.
The shop told me to re-gap the spark plug or running 91 map since it's freezing in michigan.

Good to know. It was cold that night. Do you think it’s worth it to use a colder plug?


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[allenzhang215]

Good to know. It was cold that night. Do you think it’s worth it to use a colder plug?


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I will say the OEM one is good enough. Just re-gap them if yours are still new. Or get a new sets and re-gap.

I also been told by the shop that they had customer had this issue on stage 1, after installing downpipes and went stage 2, no misfire anymore, since it took much more air compare to stock car.

[3rdBNCC]

I have tested the colder plugs (NGK) and went slower in the 1/4 mile. The OEM plugs gapped at 0.24 is more than adequate for these cars.

Edit: If you are going to go in and re-gap, might as well change them and especially if you have been running race fuel.

[mariokart]

I have tested the colder plugs (NGK) and went slower in the 1/4 mile. The OEM plugs gapped at 0.24 is more than adequate for these cars.

Edit: If you are going to go in and re-gap, might as well change them and especially if you have been running race fuel.

What are the model of the OEM plugs?


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[allenzhang215]

What are the model of the OEM plugs?


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Just give you a quick update. I have the shop ordered a new set of OEM plugs, gapped to APR recommended size. Picked up the car today, the outside temperature was 0 degree, got the car warmed up to temp. 93 MAP, beat the car hard for half hour, not a single misfire.
I guess my OEM plug size was too large.

[mariokart]

Just give you a quick update. I have the shop ordered a new set of OEM plugs, gapped to APR recommended size. Picked up the car today, the outside temperature was 0 degree, got the car warmed up to temp. 93 MAP, beat the car hard for half hour, not a single misfire.
I guess my OEM plug size was too large.

Great info, do you know the model number and gap sizing apr suggest?


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[OlyS6]

Great info, do you know the model number and gap sizing apr suggest?


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APR has been recommending Denso Iridium IKH24 plugs gapped to 0.024 to 0.026". They come with this gapping out of the box. They are one heat range colder than stock (and correspond to NGK heat range 8).

[allenzhang215]

Great info, do you know the model number and gap sizing apr suggest?


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I just have the shop ordered the OEM plug and gap them properly. The OEM part number is 079905626M

[Dasquade]

Maybe bit offtopic, but just keep in mind those recommanded Denso plugs aren't long-life plugs. Maybe good and cheaper ones, but don't forget they do need to be changed earlier (been reading of wearing out plugs and damaging the engine). That is why i want for the OEM 'M' plugs.

[allenzhang215]

Maybe bit offtopic, but just keep in mind those recommanded Denso plugs aren't long-life plugs. Maybe good and cheaper ones, but don't forget they do need to be changed earlier (been reading of wearing out plugs and damaging the engine). That is why i want for the OEM 'M' plugs.

Good point, the labor is about 250-300 for the plug change.

[mariokart]

Good point, the labor is about 250-300 for the plug change.

Wow, are those labor quotes dealer labor pricing. I’m guessing it will only take me 2 hours to change 8 plugs


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[ehofmann]

Can confirm that the NGK M plugs are gapped to 0.024 out of the box. I just checked all of mine.


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[Cris_OO7]

Any update on your misfire on cylinder 5.. I started having same issue intermittently..


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[AnesRS7]

I stated to get this.. got it randomly twice in 1 day..


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[HeelBuff]

I donated my car to science three months ago in order for APR to solve this. I believe it will be solved soon.

[cobrario]

I donated my car to science three months ago in order for APR to solve this. I believe it will be solved soon.

have you heard any updates yet? I've been talking to the guy that made the turbos being used on your car - he's made some pretty impressive numbers on the dyno at less than what he feels is max boost.

[HeelBuff]

have you heard any updates yet? I've been talking to the guy that made the turbos being used on your car - he's made some pretty impressive numbers on the dyno at less than what he feels is max boost.

Yes, but the stuff I care about hasn’t even been touched yet. They’ve been using stocker turbos and lots of instrumentation on my car to dial in the cyl #5 misfire. My posture with them changed yesterday from laid back to profound sense of urgency. They’ve had my car 2 months longer than agreed upon. I hit the ceiling when I learned they have neither tackled installing my turbos (which I paid for in early December at their behest) nor tackled fixing AMAX.

Most of the time I catch way more flies with honey than I do with vinegar. Sometimes people mistake me for a chump but I can be a nasty motherfvcker. I’m not there yet but my antennae are fully extended and I’m mustering a fury worse than a scorned woman.

[cobrario]

Yes, but the stuff I care about hasn’t even been touched yet. They’ve been using stocker turbos and lots of instrumentation on my car to dial in the cyl #5 misfire. My posture with them changed yesterday from laid back to profound sense of urgency. They’ve had my car 2 months longer than agreed upon. I hit the ceiling when I learned they have neither tackled installing my turbos (which I paid for in early December at their behest) nor tackled fixing AMAX.

Most of the time I catch way more flies with honey than I do with vinegar. Sometimes people mistake me for a chump but I can be a nasty motherfvcker. I’m not there yet but my antennae are fully extended and I’m mustering a fury worse than a scorned woman.

bummer that it's gotten to that point- I hate to say but this is a tune I've heard before- namely from Don, he can tell the story better than I can and it's prob better done off-line- you may have already heard it.

[AnesRS7]

I donated my car to science three months ago in order for APR to solve this. I believe it will be solved soon.

My Brotha!


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[mariokart]

I replaced all my plugs with Denso one step colder and a new coil for Cylinder 5. The problem is still happening. Any suggestions?


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[Cris_OO7]

Any updates solving this ?


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[Aadel@E1motorsports]

I believe we are going to see an update on this in the coming week or so. I was standing over @heelbuff ‘s car when I was told this on Saturday. The update will roll out to all RS7 and S8 software.

[mavpsire]

I believe we are going to see an update on this in the coming week or so. I was standing over @heelbuff ‘s car when I was told this on Saturday. The update will roll out to all RS7 and S8 software.

Bump - any more feedback on this update from APR?

[mariokart]

Bump - any more feedback on this update from APR?

My cylinder 5 misfire went away when I added the Miltek resonator and changed the Miltek h-pipe to my own X pipe. The exhaust sound is much smoother and has a tuned sound. I believe the track exhaust and downpipes was making the knock sensors freak out and pull ignition and fuel.
Check for vibration or loud noises


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[mavpsire]

My cylinder 5 misfire went away when I added the Miltek resonator and changed the Miltek h-pipe to my own X pipe. The exhaust sound is much smoother and has a tuned sound. I believe the track exhaust and downpipes was making the knock sensors freak out and pull ignition and fuel.
Check for vibration or loud noises.


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I was just posting in your other thread as I came across it during a search. I had the exact same thing happen two days ago...I noticed I got the flashing CEL/Cyl 5 misfire just I hit a bump that caused the car to unsettle and also shift not-so-smoothly at the same time.

Yesterday I made it a point to try a pull on a smooth surface and had no issues ugh - all this time I was convinced it was entirely a tune / operating temp issue.

[allenzhang215]

I was just posting in your other thread as I came across it during a search. I had the exact same thing happen two days ago...I noticed I got the flashing CEL/Cyl 5 misfire just I hit a bump that caused the car to unsettle.

Yesterday I made it a point to try a pull on a smooth surface and had no issues ugh - all this time I was convinced it was a tune / temperature issue.

There's still the issue that it actually registers as a Cyl 5 only vs other cyls.

It is definitely software related, otherwise APR won't work on a software update to resolve this, plus on the Enzo tune thread, the tuner pointed out there was something related to the tune as well.
On the hardware side, the the exhaust could be one of the causes.
I changed my spark plugs, the cyl 5 misfire was gone for 3 month, then it just came back. I will probably wait for the updates before touching the exhaust.
I was told by APR that they will finish validating stage 2 tune this week, and carry over to stage 1 next week.

[mavpsire]

It is definitely software related, otherwise APR won't work on a software update to resolve this, plus on the Enzo tune thread, the tuner pointed out there was something related to the tune as well.
On the hardware side, the the exhaust could be one of the causes.
I changed my spark plugs, the cyl 5 misfire was gone for 3 month, then it just came back. I will probably wait for the updates before touching the exhaust.
I was told by APR that they will finish validating stage 2 tune this week, and carry over to stage 1 next week.

Thanks Allen. Who is your contact at APR and how are you reaching them? You could PM me if you don't want to post it. My local APR rep isn't the best of help.

I've also done some logging and can see the (apparent) misfires happening even without the whole unsettling of the car. Perhaps the DPs just make it that much more louder in the engine bay causing the sensors to freak?

[allenzhang215]

Thanks Allen. Who is your contact at APR and how are you reaching them? You could PM me if you don't want to post it. My local APR rep isn't the best of help.

I've also done some logging and can see the (apparent) misfires happening even without the whole unsettling of the car. Perhaps the DPs just make it that much more louder in the engine bay causing the sensors to freak?

That's weird. My shop told me that, some customer who had who had misfire issue on stage 1, when they went to stage 2, the misfire was gone.

I just sent email directly to APR, got the response, no specific contact person

[IowaRS7]

The reality is misfires can happen for various reasons and its highly likely that not all cases are due to the same cause.

[Hofahome]

I was told by APR that they will finish validating stage 2 tune this week, and carry over to stage 1 next week.

So......two weeks lol?


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[Tuner1]

The Problem are the cars not the software....
We have another Tread already open here, when you put the Software over 750Nm you have the Misfires but take a look on the other Tread

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[allenzhang215]

The Problem are the cars not the software....
We have another Tread already open here, when you put the Software over 750Nm you have the Misfires but take a look on the other Tread

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Well, I read the other thread you posted. It could be a factor. Since on the Enzo thread, he mentioned that one guy brought car in for cylinder 5 misfire, the tuner found out the software issue, and adjusted, no misfire. I don't think it was below 750 Nm, should be way more than 750Nm

[Tuner1]

Well, I read the other thread you posted. It could be a factor. Since on the Enzo thread, he mentioned that one guy brought car in for cylinder 5 misfire, the tuner found out the software issue, and adjusted, no misfire. I don't think it was below 750 Nm, should be way more than 750Nm

Nice to hear, do you know what softwarenr you have?

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[allenzhang215]

Nice to hear, do you know what softwarenr you have?

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If you checked Enzo thread, it mentioned that APR stage 2.
I'm running APR stage 1

[Tuner1]

If you checked Enzo thread, it mentioned that APR stage 2.
I'm running APR stage 1

No i mean the Audi Software Nr....

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[Dasquade]

Maybe it is bit a combo....certain amount of Nm versus non-res/resonate type of exhaust. Not sure in what degree the (in this case milltek) resonate midpipe adds additional backpressure, same for driving with closed or open valves.