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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Powertrain and Drivetrain Discussions > N54 Turbo Engine / Drivetrain / Exhaust Modifications - 335i > Throttle closure issues



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      10-07-2015, 02:06 PM   #1
Jonjt
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Throttle closure issues

Hi All,
This is probably a question for folks like Shiv, Terry and others who have intimate knowledge of the DME and it's control algorithms.

Does anyone here know if the DME in our cars use throttle closures as a means to hit boost targets? As in, if Load Act is below target, would the DME close the throttle a bit, as a means to increase measured Manifold Air Pressure and therefore hit the Load Target?

Also, does anyone know how the DME calculates Mass Air Flow? I see it measures Pressure and Temperature but, it cant calculate mass flow from just those two variables, alone. Any idea?

Thanks
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      02-12-2016, 04:50 PM   #2
FamilyManTrackSedan
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Bump. I'd like to know this also.

My shaky understanding of tuning just to eliminate TCs flirts with these questions, but I also would like to know what the practical causes might be, how to diagnose innate issues with the car before tuning "around" easy fixes. So, how could the following CAUSE closures on an OTS stg1 tune, on an otherwise stock car:
  • not having a DCI
  • not having a FMIC
  • coils not causing legitimate misfires but maybe on their way out?
  • plugs, same as above?
  • etc...
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      02-12-2016, 09:24 PM   #3
NA55
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From what I have seen, throttle closures are usually due to actual load nearing or exceeding requested load.. I've also experienced this with boost ceiling as well.. Maybe some of the pro tuners can chime in with definite answers..

Last edited by NA55; 02-13-2016 at 12:09 AM.
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