2024 MT MHD Stg 2+ Strange Intermittent Boost Issues. Limp Mode?

[razorlab]

Yep, mine is completely limited to 650nm, doesn't hit full boost till 5k

Some of that is HPFP management strategy too.

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[ColonelAdama]

Some of that is HPFP management strategy too.

Makes sense but still had the limiter on 93 OTS as well, no where near HPFP capacity

 

[razorlab]

Makes sense but still had the limiter on 93 OTS as well, no where near HPFP capacity

Yea, just to be clear, the limiter is separate from HPFP management.

 

[ColonelAdama]

Shoutout David Shoup for pointing out the likely method to resolve this -

Two key points in the calibration:

• Open loop fueling mid-shift is changed to closed-loop for MT cars
  • smooths out hpfp demand as torque requests jump up and down mid shift.
  • prevents knock (from being lean) getting into next gear, even if single gear pull has great timing
    
• much less (almost 0) WGDC during "blow off valve" mode lol
  • Avoids keeping WGDC at 100 the entire time I'm off the pedal, causing boost spike into next gear
  • 
• Softening the clutch protection limiter should help a little too (if the clutch can handle it)

Also recommended monitoring hpfp angle and IDC.

Now just need to find these tables he was talking about and get more familiar with it.

TLDR: OTS maps suck for MT cars as everyone suspected

 

[razorlab]

Shoutout David Shoup for pointing out the likely method to resolve this -

Two key points in the calibration:

• Open loop fueling mid-shift is changed to closed-loop for MT cars
  • smooths out hpfp demand as torque requests jump up and down mid shift.
  • prevents knock getting into next gear, even if single gear pull has great timing
    
• much less (almost 0) WGDC during "blow off valve" mode lol
  • Avoids keeping WGDC at 100 the entire time I'm off the pedal, causing boost spike into next gear
  • 
• Softening the clutch protection limiter should help a little too (if the clutch can handle it)

Now just need to find these tables he was talking about and get more familiar with it.

TLDR: OTS maps suck for MT cars as everyone suspected

Man, you need something that has better data rate while logging. Are you just logging a ton of items and/or a slow device?

WGDC during Blow Off table is "BMWtchout_pct_WgBlwOff_T"

You might want to mess around with P-gain limitation during shifts. "BMWtchctr_ti_ToutPpLim_C"

 

[ColonelAdama]

Man, you need something that has better data rate while logging. Are you just logging a ton of items and/or a slow device?

WGDC during Blow Off table is "BMWtchout_pct_WgBlwOff_T"

Its possible that I am logging more than I need to. I added links so you can see what parameters. Should be just standard parameters with a few I thought would be useful in addition.

Device is Galaxy S24 so plenty of computing power.

Thanks for the table!

 

[razorlab]

Its possible that I am logging more than I need to. I added links so you can see what parameters. Should be just standard parameters with a few I thought would be useful in addition.

Device is Galaxy S24 so plenty of computing power.

Thanks for the table!

Def something going on. What obd2 dongle?

For reference, here is a MT custom tune log (WIP), with about the same amount of logging items as you.

 

[ColonelAdama]

Def something going on. What obd2 dongle?

For reference, here is a MT custom tune log (WIP), with about the same amount of logging items as you.

Maybe because it was starting in 2nd. Here is a full 3rd gear sweep which would be better comparison to what you sent:
https://datazap.me/u/coloneladama/log-1768230024?log=0&data=3-4-6-17-20-21-22-23-24-25

Dongle is the newest red MHD universal wifi one

 

[razorlab]

Maybe because it was starting in 2nd. Here is a full 3rd gear sweep which would be better comparison to what you sent:
https://datazap.me/u/coloneladama/log-1768230024?log=0&data=3-4-6-17-20-21-22-23-24-25

Dongle is the newest red MHD universal wifi one

Ah, I didn't even notice the lower gear in your log.

 

[ColonelAdama]

Ah, I didn't even notice the lower gear in your log.

Do you happen to know the table name for the open vs closed looped fueling mid shift?

I think this ultimately is the cause of the 262144 limp mode this thread is about. Car is basically knocking on the shift since it is at 18+ afr and 15+ lbs boost.

 

[razorlab]

Do you happen to know the table name for the open vs closed looped fueling mid shift?

I think this ultimately is the cause of the 262144 limp mode this thread is about. Car is basically knocking on the shift since it is at 18+ afr and 15+ lbs boost.

I think that is more the OTS than anything. Properly tuned they don't do that. Not sure what table he was referring too, although I might be changing it and just calling it something different.

 

[RacerJohnny]

Just curious - if custom tune can resolve this, has the issue between OTS and MT cars been relayed back to MHD/Pureboost? Maybe it’s just wishful thinking but I’d think/hope they’d either put some disclaimer that OTS maps are AT only, and/or that Pureboost would be capable of tweaking the OTS maps to eliminate the boost spikes during shifting specific for the MT cars.

I know custom is always better, but it seemed here that people respected the MHD OTS maps so that was a selling point for me short-term (saving the custom tune $$$ for when upgrading turbo next).

 

[BMWAF]

Just curious - if custom tune can resolve this, has the issue between OTS and MT cars been relayed back to MHD/Pureboost? Maybe it’s just wishful thinking but I’d think/hope they’d either put some disclaimer that OTS maps are AT only, and/or that Pureboost would be capable of tweaking the OTS maps to eliminate the boost spikes during shifting specific for the MT cars.

I know custom is always better, but it seemed here that people respected the MHD OTS maps so that was a selling point for me short-term (saving the custom tune $$$ for when upgrading turbo next).

Might be worth reaching out.

 

[swrdply400mrelay]

Not sure how this works, but couldn’t someone tweak the OTS map and make it available for people to download as a map?

 

[itzTang]

Not sure how this works, but couldn’t someone tweak the OTS map and make it available for people to download as a map?

Called getting a tuner

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