[eeyang92]

Hey all,

Before I go running off to buy a set of upgraded coils (most likely the B58 coils + nesys mounting kit), I'm wondering if anyone is familiar with what would cause what is shown in the log? https://www.bootmod3.net/log?id=62a7...729b049521b434

Mod List:

- Upgraded CP, BP, 200 Cell DP, MST Inlet, 5" Intercooler
- Dorch Stage 2 HPFP
- 3.5 bar TMAP (although I feel like maybe I got sent the wrong one because there seems to be a large delta between boost pre-throttle and the MAP sensor after the turbo spools up lol, P/N checks out though)
- Pure Stage 2 Turbo /w VR11 BOV
- BM3 Stage 2+ E30 OTS Map with flex fuel (running E46 in the log)
- New N55 coils and 1-step colder NGK spark plugs gapped to ~0.023" (as recommended by bootmod3)

Right about 6500 RPM in the 3rd gear run you can see the RPM start fluctuating wildly and the car feels like it almost hits a soft limiter - I assume this is a some sort of misfire and/or the flame being blown out by my E46 mix (no codes, though)? I'm guessing this may be remedied by gapping even smaller, but I hear that can lead to rough idling and less efficient combustion, so that is not my preferred route.

HPFP looks good so I don't think it could be fueling related - would the LPFP not being able to keep up also result in this issue even if HPFP is holding pressure?

I had another run with E32 which didn't seem to have the stumbling at 6500+ RPM: https://www.bootmod3.net/log?id=62a9...90c60d16821337

However, I'm not sure if it's a 1-to-1 comparison since the octane is much lower (due to less E, plus bad CA gas) and IATs ~10 degrees hotter so the car pulled much more timing which may have prevented the engine from reaching the same levels as in the first log.

Perhaps the most efficient way would be to try gapping to around 0.02" and see how that affects the car and see if it resolves the issue at the top end?

Sorry for the long winded post, but if anyone has any ideas and has run into this before, any input would be greatly appreciated!

TIA!

[designatedposter]

the log you posted doesn't show any issues.

1. if you changed the tmap sensor, did you ensure you made the change in tune configuration and flash? looking at your log, it is common in bm3 tunes to overshoot boost target at spool, then the throttle plate is used to correct. the tmap will show a higher boost (pre throttle plate) vs the map which is post throttle plate. so overall, the tmap behavior in your log is normal for this tune.
2. the title of your log is multimap stage 2+, not per your description of stage 2+ e30..
3. your spark plug gap is off by a decimal point... are you sure you are at .0023" and not .023"? stock gap is ~.031"

[eeyang92]

Originally Posted by designatedposter

the log you posted doesn't show any issues.

1. if you changed the tmap sensor, did you ensure you made the change in tune configuration and flash? looking at your log, it is common in bm3 tunes to overshoot boost target at spool, then the throttle plate is used to correct. the tmap will show a higher boost (pre throttle plate) vs the map which is post throttle plate. so overall, the tmap behavior in your log is normal for this tune.
2. the title of your log is multimap stage 2+, not per your description of stage 2+ e30..
3. your spark plug gap is off by a decimal point... are you sure you are at .0023" and not .023"? stock gap is ~.031"

Hey! Thanks for the response.

1. Yes, it is set to 3.5 bar - and I'm glad to hear it's fairly normal to overshoot at spool. So in general, MAP is the more relevant value to be looking at and not the pre-throttle boost?
2. Ah sorry, yes my mistake - to clarify it is indeed the multimap stage 2+ on the E30 map (map 1) with flex fuel enabled
3. Indeed it should be 0.023" - that's what I get for posting at 3am my time

Regarding the issue of the top end of the first log I posted (https://www.bootmod3.net/log?id=62a7...729b049521b434) - I think I can see the engine pretty much sputtering 6500+ RPM, and I can definitely feel the engine stop pulling (at which point I got off the throttle since I don't want to cause damage).

[designatedposter]

Originally Posted by eeyang92

Hey! Thanks for the response.

1. Yes, it is set to 3.5 bar - and I'm glad to hear it's fairly normal to overshoot at spool. So in general, MAP is the more relevant value to be looking at and not the pre-throttle boost?
2. Ah sorry, yes my mistake - to clarify it is indeed the multimap stage 2+ on the E30 map (map 1) with flex fuel enabled
3. Indeed it should be 0.023" - that's what I get for posting at 3am my time

Regarding the issue of the top end of the first log I posted (https://www.bootmod3.net/log?id=62a7...729b049521b434) - I think I can see the engine pretty much sputtering 6500+ RPM, and I can definitely feel the engine stop pulling (at which point I got off the throttle since I don't want to cause damage).

i must have looked at the wrong log. all my comments were for this log: https://www.bootmod3.net/log?id=62a9...90c60d16821337

[designatedposter]

after reviewing the right log, i can see the issue now. you have throttle closure to 75% at 6500rpm (adds to the sensation of misfire), but unknown what caused it. lambda is non typical after 5700 rpm. the load actual is also strange after 5700 rpm.

i'm inclined to agree this might be a fuel issue, however, gapping tighter is free and at one point when i was as tight as .018, my idle and mpg was fine.

[eeyang92]

Originally Posted by designatedposter

after reviewing the right log, i can see the issue now. you have throttle closure to 75% at 6500rpm (adds to the sensation of misfire), but unknown what caused it. lambda is non typical after 5700 rpm. the load actual is also strange after 5700 rpm.

i'm inclined to agree this might be a fuel issue, however, gapping tighter is free and at one point when i was as tight as .018, my idle and mpg was fine.

Hm, yeah now that you mention it, the AFR does seem to be on the "leaner" side compared to the other run, and it is all over the place.

Thanks for the suggestion, I'll try going down to 0.02" and then 0.018" if the issue still persists.

I haven't heard much of a need to upgrade the LPFP but perhaps it may be needed here (and maybe fix the low fuel pickup issue at the same time). Dorch Stage 2 should be good for ~550 WHP on E50 (taking a conservative average of their claims from their site: https://dorchengineering.com/product...-hpfp-upgrade/), and I'm pretty sure my car is not making anywhere near that, so I don't think I'll need to get their Lift Kit.

[ZM2]

Kinda similar issue here with a tuned PS2 setup. Maybe there’s some kind of limit in the OTS maps that you guys are hitting?

https://f30.bimmerpost.com/forums/sh....php?t=1922739

Worth an ask to PTF.

[eeyang92]

Originally Posted by ZM2

Kinda similar issue here with a tuned PS2 setup. Maybe there’s some kind of limit in the OTS maps that you guys are hitting?

https://f30.bimmerpost.com/forums/sh....php?t=1922739

Worth an ask to PTF.

Hey ZM2, thanks for that! Indeed it feels eerily similar to what motivman experienced - basically it feels like I hit a soft limiter, although my E limit was only around E40-45 (stock LPFP) @ 20 PSI on the top end. I think am going to order B58 coils + conversion kit to see if it's potentially the spark not being able to bridge the gap.

I also did get in contact with Halim and he pointed out similarly how the AFR was not normal, and it is potentially the coils/plugs. But if not, I will try the LPFP after that. I'm only targeting E50 at most so if I don't have to upgrade the LPFP that would be preferrable, but perhaps it may have to be the case.

[Nandohatesyou]

Originally Posted by eeyang92

Hey ZM2, thanks for that! Indeed it feels eerily similar to what motivman experienced - basically it feels like I hit a soft limiter, although my E limit was only around E40-45 (stock LPFP) @ 20 PSI on the top end. I think am going to order B58 coils + conversion kit to see if it's potentially the spark not being able to bridge the gap.

I also did get in contact with Halim and he pointed out similarly how the AFR was not normal, and it is potentially the coils/plugs. But if not, I will try the LPFP after that. I'm only targeting E50 at most so if I don't have to upgrade the LPFP that would be preferrable, but perhaps it may have to be the case.

Did you ever get this sorted out?

[eeyang92]

Originally Posted by Nandohatesyou

Did you ever get this sorted out?

Hey, yes I did! Solution was to swap to B58 coils (or decreasing the gap would probably accomplish the same thing, but not as optimal).

I'm running stock gap on B58 coils with E45-E50 mix without any stuttering now.