Close

Results 1 to 20 of 20
  1. #1
    Join Date
    Aug 2018
    Posts
    41
    Rep Points
    49.0
    Mentioned
    1 Post(s)
    Rep Power
    0


    Yes Reputation No

    Weird boost issue with MHD stage 2+ (log inside)

    Hi everyone,

    I'm experiencing something odd and i don't know if this normal for the MHD OTS S2+.
    Everytime i floor it below or at 3000 (where boost comes on), my boost fluctuates a tiny bit and then settles at 4k rpm.
    Not enough to really annoy me, but just enough to feel in the seat of the pants dyno.
    Here is a log:

    https://datazap.me/u/dutchman/09-01-...=0&data=3-4-21
    https://datazap.me/u/dutchman/09-01-...=1&data=3-4-21

    You can see boost fluctuates from 3-4k and smooths out in the higher rpm's.
    If i downshift (to 4000+), there is no fluctuation and it's just very smooth.
    I noticed this with stage 1 to stage 2+, so i'm thinking boost control from the OTS map or something hardware related?
    I also have some throttle closures, but i'm not sure the 2 are related..

    It's almost as if the turbo's want to spool harder than the map asks it to Click here to enlarge
    If you look at the WGDC, you can see tries to adjust constantly around 3k rpm.
    AFAIK the turbo's are stock and my setup is pretty much FBO on pump gas:
    MHD stage 2+ (95RON) + catless DP's, VRSF CP, FMIC and DCI's.

    Can i have someones opinion on this?
    Thank you!

  2. #2
    Join Date
    Jan 2018
    Posts
    9
    Rep Points
    38.0
    Mentioned
    0 Post(s)
    Rep Power
    0


    Yes Reputation No
    You have high timing corrections only in low rpm, that's weird because it's not in high rpm, so not really fuel related as your map is correct for 95 RON. If the last time you changed spark plugs was more then 10000 km ago you should replace them first. Maybe also scan for codes with the MHD app. Also you say your FBO with intercooler but you IAT's rise very quickly.

  3. #3
    Join Date
    Aug 2018
    Posts
    41
    Rep Points
    49.0
    Mentioned
    1 Post(s)
    Rep Power
    0



    Yes Reputation No
    Yes i put 98RON in the car while the map is S2+ 95RON, so octane-wise it should be fine.
    Coils were replaced 6k mls ago and plugs were replaced 2k mls ago (one step colder).
    I have no fault codes in Carly, MHD or ProTool.
    My IAT's rise to 32ļC in a long 5th gear pull, so my speed is around 250 km/h at that time (on a private road, obviously).
    So temps are not too bad, i think?
    I have the VRSF 7" FMIC mounted, so should be sufficient.

    I have the RB external PCV with 2 catch cans (high & low side), so intake caking should be reduced to a minimum.
    However there could be some dirt in the intake left from the 60k mls driven by the previous owner..

  4. #4
    Join Date
    Jan 2010
    Location
    SoCal
    Posts
    137,710
    Rep Points
    41,019.0
    Mentioned
    2418 Post(s)
    Rep Power
    411


    Yes Reputation No
    Click here to enlarge Originally Posted by DutchBMW Click here to enlarge
    Yes i put 98RON in the car while the map is S2+ 95RON, so octane-wise it should be fine.
    Coils were replaced 6k mls ago and plugs were replaced 2k mls ago (one step colder).
    I have no fault codes in Carly, MHD or ProTool.
    My IAT's rise to 32ļC in a long 5th gear pull, so my speed is around 250 km/h at that time (on a private road, obviously).
    So temps are not too bad, i think?
    I have the VRSF 7" FMIC mounted, so should be sufficient.

    I have the RB external PCV with 2 catch cans (high & low side), so intake caking should be reduced to a minimum.
    However there could be some dirt in the intake left from the 60k mls driven by the previous owner..
    @DutchBMW figure it out?

  5. #5
    Join Date
    Aug 2018
    Posts
    41
    Rep Points
    49.0
    Mentioned
    1 Post(s)
    Rep Power
    0



    1 out of 1 members liked this post. Yes Reputation No
    Sadly... no.
    It drives fine, but still does this boost fluctuation thing.
    Done a smoke test test, but no leaks found.
    I (sort of) accepted this as being normal with an OTS map and i may require a custom map...
    But for real, i still have no clear answer for it.

  6. #6
    Join Date
    Jan 2010
    Location
    SoCal
    Posts
    137,710
    Rep Points
    41,019.0
    Mentioned
    2418 Post(s)
    Rep Power
    411


    Yes Reputation No
    Click here to enlarge Originally Posted by DutchBMW Click here to enlarge
    I (sort of) accepted this as being normal with an OTS map and i may require a custom map...
    And when on the stock map everything is fine?

  7. #7
    Join Date
    Aug 2018
    Posts
    41
    Rep Points
    49.0
    Mentioned
    1 Post(s)
    Rep Power
    0



    Yes Reputation No
    It is, yes.
    I've read that the WGDC is capped with the stock map and it's derestricted on the OTS maps to ensure a quick and agressive spool.
    That's why i think it needs to be custom mapped to create an optimum WGDC maximum for my engine..

    I could be wrong though and maybe one of the wastegates is leaking a tiny bit, but then i expect it to run worse the higher the rpm's go (more work for the turbo's).
    It just runs perfect in the higher rpm's.

  8. #8
    Join Date
    Dec 2017
    Posts
    24
    Rep Points
    31.0
    Mentioned
    0 Post(s)
    Rep Power
    0


    Yes Reputation No
    Looks like load based tuning. So the car is having throttle closures when it meets or exceeds the requested load.

    Between your throttle closures and WGDC your boost is fluctuating after you have spooled. Near the top of the rpm range the throttle closures are not as severe so you don't notice the fluctuating boost.

    MHD keeps the older revisions in the catalog of tunes to use. You could try a different revision, log, and see if that revision fits your car better.
    2008 E92 BMW 335i 6MT
    DocRace 6266 | Boostbox | Mfactory Flywheel | Spec 3+ | VRSF Race Intercooler | Rewired Walbro 525

  9. #9
    Join Date
    Aug 2018
    Posts
    41
    Rep Points
    49.0
    Mentioned
    1 Post(s)
    Rep Power
    0



    Yes Reputation No
    Yes, i will try that, thank you!
    I'll report back with my findings.

  10. #10
    Join Date
    Mar 2019
    Posts
    3
    Rep Points
    6.0
    Mentioned
    0 Post(s)
    Rep Power
    0


    2 out of 2 members liked this post. Yes Reputation No
    Click here to enlarge Originally Posted by DutchBMW Click here to enlarge
    Yes i put 98RON in the car while the map is S2+ 95RON, so octane-wise it should be fine.
    Coils were replaced 6k mls ago and plugs were replaced 2k mls ago (one step colder).
    I have no fault codes in Carly, MHD or ProTool.
    My IAT's rise to 32ļC in a long 5th gear pull, so my speed is around 250 km/h at that time (on a private road, obviously).
    So temps are not too bad, i think?
    I have the VRSF 7" FMIC mounted, so should be sufficient.

    I have the RB external PCV with 2 catch cans (high & low side), so intake caking should be reduced to a minimum.
    However there could be some dirt in the intake left from the 60k mls driven by the previous owner..
    I take the end of this post to mean you haven't done a walnut blast? If not, i'd start with that.

  11. #11
    Join Date
    May 2011
    Posts
    796
    Rep Points
    454.8
    Mentioned
    4 Post(s)
    Rep Power
    5


    Yes Reputation No
    Click here to enlarge Originally Posted by type-dRew Click here to enlarge
    I take the end of this post to mean you haven't done a walnut blast? If not, i'd start with that.
    When tuning, the engine must be in pristine condition. Everything, or you will get bitten.

    Deferred maintenance is not an option.

  12. #12
    Join Date
    Aug 2018
    Posts
    41
    Rep Points
    49.0
    Mentioned
    1 Post(s)
    Rep Power
    0



    Yes Reputation No
    Yes, thank you for the replies, gentlemen.
    I already made an appointment for a walnut blast session, so will be done in 2 weeks.
    I had the intake off some time ago and the valve were black, but not really caked up like you see sometimes, so shouldn't be too much of a restriction, but we'll see what this does to the performance.
    Thanks again and i'll report back ;-)

  13. #13
    Join Date
    Apr 2019
    Posts
    3
    Rep Points
    2.0
    Mentioned
    0 Post(s)
    Rep Power
    0


    Yes Reputation No
    Your boost is within 1 psi of target which is acceptable
    Throttle closures happen when over boosting (which you were a bit mid rpm) or you have traction control activated, did you deactivate it when doing the log?
    Timing corrections look fine as there are none during the pull
    What is strange to me is your LTFT's should be at 0% during WOT, STFT are negative which is usually a sign of running rich.

  14. #14
    Join Date
    Aug 2018
    Posts
    41
    Rep Points
    49.0
    Mentioned
    1 Post(s)
    Rep Power
    0



    Yes Reputation No
    Yes, my thoughts exactly about the psi differential.
    Traction control was fully off, so no issues on that part.

    Could the rich running be one of the following:
    - Dirty intake - less CFM - walnut blasting necessary?
    - O2 sensors maybe lazy or worn (80k miles on first set).

    I tried running the stock map BTW and the issue was gone.
    No fluttering or boost oscillation on the stock 8 psi (give or take).
    This makes me lean more into looking for a proper custom tune..

  15. #15
    Join Date
    Apr 2019
    Posts
    3
    Rep Points
    2.0
    Mentioned
    0 Post(s)
    Rep Power
    0


    1 out of 1 members liked this post. Yes Reputation No
    Custom tune will always be better as the tuner can tweak things specifically for your engine.
    You are correct, as your o2's age they get lazy and it can affect Fuel Trims.
    Just looking back at your logs again the STFT's never spike to -34 during the pull which is ok, if you get to -34 and stay there for a period of time then you have an issue. Still though the LTFT as far as I know should be at 0 during WOT.
    Have many kms on your car?
    I would get a walnut blast regardless if you have never had one before.
    Can you post a log at idle? Idle for 30 seconds then increase to 1500rpm for 30 seconds and increase to 2000rpm for 30 seconds.

  16. #16
    Join Date
    Aug 2018
    Posts
    41
    Rep Points
    49.0
    Mentioned
    1 Post(s)
    Rep Power
    0



    1 out of 1 members liked this post. Yes Reputation No
    Okay, i have an update guys!
    i did the walnut blast and although it made a difference in smoothness (idle, throttle response), there’s no difference in boost.
    Still boosts very agressively and still fluctuates a bit.
    MHD Stage 0, 1 & 2 maps have NO fluctuation and actually build boost very smooth.
    It’s the plus maps that don’t work very smooth and give me the slight fluctuation.

    I think my next logical step would be a custom tune.

  17. #17
    Join Date
    Mar 2019
    Posts
    3
    Rep Points
    6.0
    Mentioned
    0 Post(s)
    Rep Power
    0


    1 out of 1 members liked this post. Yes Reputation No
    Click here to enlarge Originally Posted by DutchBMW Click here to enlarge
    Okay, i have an update guys!
    i did the walnut blast and although it made a difference in smoothness (idle, throttle response), thereís no difference in boost.
    Still boosts very agressively and still fluctuates a bit.
    MHD Stage 0, 1 & 2 maps have NO fluctuation and actually build boost very smooth.
    Itís the plus maps that donít work very smooth and give me the slight fluctuation.

    I think my next logical step would be a custom tune.
    Did you try V7 maps? I'd describe my experience with the beta v8.0 maps as 'not smooth', im now using v7 and they fixed all my complaints and I like the part throttle stuff a lot more too.

  18. #18
    Join Date
    Aug 2018
    Posts
    41
    Rep Points
    49.0
    Mentioned
    1 Post(s)
    Rep Power
    0



    Yes Reputation No
    Oh wow, never tried that actually!
    I read so much good stuff about the V8 maps, that i never tried the V7 ones.
    I should have tried this alot earlier, but never thought about it.

    I’ll try it and report back ;-)

  19. #19
    Join Date
    Aug 2018
    Posts
    41
    Rep Points
    49.0
    Mentioned
    1 Post(s)
    Rep Power
    0



    1 out of 1 members liked this post. Yes Reputation No
    I tried the V7 maps and although it's a bit smoother, it's still pretty agressive and not supersmooth..

    I tried the RFP stage 2 OTS map and although boost is higher (17.5 psi instead of 16.5 psi i had before), it's supersmooth: No boost oscillation or fluctuation, no timing corrections and even more mid range torque.
    I think it has something to do with the WGDC limit, being lower on RFP's map.

    I think i can safely assume the tune was the culprit and a custom tune is probably the best step forward.
    You just can't expect perfection from an OTS map, i guess.

    Thanks everyone for the helpful replies :-)

  20. #20
    Join Date
    Jan 2010
    Location
    SoCal
    Posts
    137,710
    Rep Points
    41,019.0
    Mentioned
    2418 Post(s)
    Rep Power
    411


    Yes Reputation No
    Click here to enlarge Originally Posted by DutchBMW Click here to enlarge
    I tried the RFP stage 2 OTS map and although boost is higher (17.5 psi instead of 16.5 psi i had before), it's supersmooth: No boost oscillation or fluctuation, no timing corrections and even more mid range torque.
    I think it has something to do with the WGDC limit, being lower on RFP's map.
    Interesting...

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may post replies
  • You may not post attachments
  • You may not edit your posts
  •