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BMW M5 F90 (2018+) General Forums Engine, Exhaust, Drivetrain, Tuning Modifications    Rough Engine Start Up With Stage 2 BM3

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      08-15-2020, 09:49 PM   #1
ec_101
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Rough Engine Start Up With Stage 2 BM3

I currently have SSR castles primary downpipes w/ BM3 stage 2 91. I kept the stock secondary downpipes.

On BM3 configurations I have cold start set as OFF. When starting up the car the engine runs rough feels like it's about to stall, almost like it's out of gas. Once the car runs about 30-45 seconds it runs smooth.

Anyone else experience this with cold start shut off ? Should I have cold start set to on since I still have cats in my secondary downpipes ? Thanks for your input!
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      08-16-2020, 02:43 PM   #2
Higgs Boson
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I don't think the OTS tunes are properly tuned for a low RPM cold temp startup. All the cold start shut off does is a hard cut to RPM. There's more to it than that to do it properly.
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      08-16-2020, 07:58 PM   #3
PGF90
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Had the same issue ended up turning cold start back on.
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      08-17-2020, 01:21 PM   #4
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Had the same issue on 2 F90's. Solution is to turn Cold start ON.
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      08-17-2020, 02:22 PM   #5
GranitM5
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My tuner never asked me for the feature. Must have been a reason for that
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