[AdventureNoodle]

Hey everyone, I have an N55 M2 and I am running full E85 (Dorch Stage 2) and in the process of getting a custom tune done for my car. I was at a car show and banged the rev limiter cause the crowd wanted to see it and then I got the following codes in the attached image. The car idled really rough and I was like "alright I effed the engine up and I'm going to need a new one".

I shut the car down, ran the diagnostics using BM3 and cleared the codes, prayed, and restarted it and it fired up and has been idling with no problem so far. Did a 3rd gear pull WOT and car seems fine. Code hasn't come back.

Should I be worried about this? Did my car just freak out at me because I banged it off the limiter for a few seconds? Any feedback (positive or negative) would be greatly appreciated.

[-Eidos]

Originally Posted by AdventureNoodle

Should I be worried about this? Did my car just freak out at me because I banged it off the limiter for a few seconds? Any feedback (positive or negative) would be greatly appreciated.

If all you did was bang the rev limiter and the codes no longer show up then you're *probably* fine. Best would be to consult your tuner and they should be able to tell you if there are any issues from your logs.

[AdventureNoodle]

Originally Posted by -Eidos

If all you did was bang the rev limiter and the codes no longer show up then you're *probably* fine. Best would be to consult your tuner and they should be able to tell you if there are any issues from your logs.

Yup! Looks like I'm waiting till Monday

[AdventureNoodle]

Originally Posted by AdventureNoodle

Yup! Looks like I'm waiting till Monday

Also based on what I can tell. The logs are good. No serious (out of the normal) timing pulls from cylinder 2 on WOT. I went ahead and ordered new plugs and coils, and I'll make sure I order new injectors if I have to.

Once again, just waiting on the tuner hahah

[F87source]

Originally Posted by AdventureNoodle

Also based on what I can tell. The logs are good. No serious (out of the normal) timing pulls from cylinder 2 on WOT. I went ahead and ordered new plugs and coils, and I'll make sure I order new injectors if I have to.

Once again, just waiting on the tuner hahah

Smart call replacing the plugs after a super knock event.

Super knock is really really bad, but if you were doing it while neutral just revving it that should be less detrimental because there was no load on the engine and likely you wouldn't be making huge boost - especially without antilag. Again like others have said just talk to a tuner about it, the car should never have super knock under any circumstance so yeah have your tuner address it.

[AdventureNoodle]

Originally Posted by F87source

Smart call replacing the plugs after a super knock event.

Super knock is really really bad, but if you were doing it while neutral just revving it that should be less detrimental because there was no load on the engine and likely you wouldn't be making huge boost - especially without antilag. Again like others have said just talk to a tuner about it, the car should never have super knock under any circumstance so yeah have your tuner address it.

Thank you, yeah I'm trying to be as safe and smart about this as possible. I want to get a look at the plugs and make sure there was no piston to plug contact during that event. Thankfully the rods are forged in the M2's N55 so hopefully nothing bent there. Car still feels fast thankfully - hit 175 in Mexico later that night when the car didn't throw another super knock code after I cleared and restarted it. Still hasn't thrown a code, but I switched to a much lower boost tune just to be safe. Stage 2 OTS multimap with BM3 instead of the custom tune, at least till we can determine what happened with the super knock

[F87source]

Originally Posted by AdventureNoodle

Thank you, yeah I'm trying to be as safe and smart about this as possible. I want to get a look at the plugs and make sure there was no piston to plug contact during that event. Thankfully the rods are forged in the M2's N55 so hopefully nothing bent there. Car still feels fast thankfully - hit 175 in Mexico later that night when the car didn't throw another super knock code after I cleared and restarted it. Still hasn't thrown a code, but I switched to a much lower boost tune just to be safe. Stage 2 OTS multimap with BM3 instead of the custom tune, at least till we can determine what happened with the super knock

The piston will never hit the spark plug under any circumstance, even if you over rev the car or money shift. The only way it can do so is if the plug was over threaded and some how went too deep - but the head would be absolutely screwed if this was the case, or if the piston snapped off the end of the rod and went shooting out of the engine, or if the rod cap blew off allowing the whole assembly to shoot up. Otherwise there's no way the piston can ever contact the spark plug, valve to piston yes if you money shift but never piston to spark plug unless something went horribly wrong.


Next super knock could damage the spark plug tips (electrode, ceramic etc) which is why you'd swap them out. Not for plug to piston contact which would never happen. Also you'd likely never bend the rod even if you hit the valves or the spark plug, the rod is so much stronger than the valves or the spark plug those would bend first along with denting your pistons. Also Super knock is a huge knock event which could crack pistons and bend rods due to the huge cylinder pressures that occur due to the preignition happening so far before TDC that the combustion gas expansion combined with the compression due to the piston moving up creates astronomical amounts of pressure. This pressure will possibly bend rods and crack pistons not any form of contact. So the best way to check for piston damage is a leak down test and maybe a bore scope visual inspection, rod damage will be harder to check for.


But again I don't think anything too major occured if you were only revving it.

[AdventureNoodle]

Originally Posted by F87source

The piston will never hit the spark plug under any circumstance, even if you over rev the car or money shift. The only way it can do so is if the plug was over threaded and some how went too deep - but the head would be absolutely screwed if this was the case, or if the piston snapped off the end of the rod and went shooting out of the engine, or if the rod cap blew off allowing the whole assembly to shoot up. Otherwise there's no way the piston can ever contact the spark plug, valve to piston yes if you money shift but never piston to spark plug unless something went horribly wrong.


Next super knock could damage the spark plug tips (electrode, ceramic etc) which is why you'd swap them out. Not for plug to piston contact which would never happen. Also you'd likely never bend the rod even if you hit the valves or the spark plug, the rod is so much stronger than the valves or the spark plug those would bend first along with denting your pistons. Also Super knock is a huge knock event which could crack pistons and bend rods due to the huge cylinder pressures that occur due to the preignition happening so far before TDC that the combustion gas expansion combined with the compression due to the piston moving up creates astronomical amounts of pressure. This pressure will possibly bend rods and crack pistons not any form of contact. So the best way to check for piston damage is a leak down test and maybe a bore scope visual inspection, rod damage will be harder to check for.


But again I don't think anything too major occured if you were only revving it.

Yeah maybe a leak down test is in order. Car sounds fine when I crank it and it idles perfectly. Probably going to do a scope + leak down test to see if any of the pistons are damaged. I'm trusting the rods will be okay. Fingers crossed for both!

Here is a WOT 3rd gear log I took after I cleared the super knock codes and they didn't come back. Think you could provide some insight before my tuner gets back to me on Monday?

https://www.bootmod3.net/log?id=61d9...0b434a91ee8dda

Based on the timing in this log, everything looked fine to me, so I did a high speed high load run to see if it would come back and it took it just fine:

https://www.bootmod3.net/log?id=61d9...90c630d62f94ff

FYI both were on around E75-E80 fuel

[AdventureNoodle]

Originally Posted by AdventureNoodle

Yeah maybe a leak down test is in order. Car sounds fine when I crank it and it idles perfectly. Probably going to do a scope + leak down test to see if any of the pistons are damaged. I'm trusting the rods will be okay. Fingers crossed for both!

Here is a WOT 3rd gear log I took after I cleared the super knock codes and they didn't come back. Think you could provide some insight before my tuner gets back to me on Monday?

https://www.bootmod3.net/log?id=61d9...0b434a91ee8dda

Based on the timing in this log, everything looked fine to me, so I did a high speed high load run to see if it would come back and it took it just fine:

https://www.bootmod3.net/log?id=61d9...90c630d62f94ff

FYI both were on around E75-E80 fuel

This is the log that threw the Super Knock Code:

https://www.bootmod3.net/log?id=61d8...90c630d62f94b3

This is the idle right after:

https://www.bootmod3.net/log?id=61d8...729b734798c054

This was idling after clearing the codes and restarting the engine:

https://www.bootmod3.net/log?id=61d8...90c632d97c4223

[ZM2]

After logs look ok to me, but you guys aren’t even pushing that hard yet (20.3psi, 8deg of timing). For example, we’re currently at 22.2psi & 16deg with the Stg 2+ E50 beta with no issues. Even the OTS 2+ Multimap runs more boost & timing than your log.

Hopefully it’s ok and you guys can keep pushing. I didn’t have a very good experience with Cary, and his maps didn’t run right on my car while at the very same time Halim’s Stg 2+ E30 beta maps ran perfect when we were working on those for the OTS back in summer 2020.

Once you’re happy with Cary’s map my suggestion is to hit a Dynojet and compare it to the BM3 Stg 2+ maps to see how the curves differ.

[AdventureNoodle]

Originally Posted by ZM2

After logs look ok to me, but you guys aren't even pushing that hard yet (20.3psi, 8deg of timing). For example, we're currently at 22.2psi & 16deg with the Stg 2+ E50 beta with no issues.

Hopefully it's ok and you guys can keep pushing. I didn't have a very good experience with Cary, and his maps didn't run right on my car while at the very same time Halim's Stg 2+ E30 beta maps ran perfect when we were working on those back in 2019.

Thank you so much. I am relieved to hear that. I was worried there might be some serious damage.

Yeah I'm just hoping it was a freak accident. Cary had tuned so many of my friends cars that are amazing so I trust him to make a safe tune.

The issue is why did this happen when the car wasn't even being pushed hard? Are my knock sensors just that out of whack? I have 0 knock right now on the Stage 2 Multimap and the code hasn't come back.

I should also add that I was running like E77 when this happened.

[ZM2]

Originally Posted by AdventureNoodle

Thank you so much. I am relieved to hear that. I was worried there might be some serious damage.

Yeah I'm just hoping it was a freak accident. Cary had tuned so many of my friends cars that are amazing so I trust him to make a safe tune.

The issue is why did this happen when the car wasn't even being pushed hard? Are my knock sensors just that out of whack? I have 0 knock right now on the Stage 2 Multimap and the code hasn't come back.

Doubtful it’s knock sensor related or you would be getting codes all the time.

Has to be tune related. I’ve never seen superknock from all my years of tuning with Halim, even with a ton of track time. Let us know how it goes!

[AdventureNoodle]

Originally Posted by ZM2

Doubtful it's knock sensor related or you would be getting codes all the time.

Has to be tune related. I've never seen superknock from all my years of tuning with Halim, even with a ton of track time. Let us know how it goes!

I'm just happy it was super knock in neutral and not when I was moving. That said, car was still making like 18psi when the code was thrown 😅

I will definitely keep you posted on how it goes!

[S333_YOV_F80_M3]

Hi mate i have same issue on mine did you manage to find out what it was ??

Thanks

[AdventureNoodle]

Originally Posted by S333_YOV_F80_M3

Hi mate i have same issue on mine did you manage to find out what it was ??

Thanks

I just stopped free revving it lol. If it happened to you under load, that’s a very bad thing and could mean engine trouble