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2Addicts | BMW 2-Series forum Technical Topics N55 (M235i) Engine, Transmission, Exhaust, Tuning Hotwire MAP sensor on stage 2 tune? Please advise!

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      07-28-2019, 10:43 AM   #1
bplewis78
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Hotwire MAP sensor on stage 2 tune? Please advise!

Hi,

This is my first post, so please forgive any poor protocol.

I have owned my 2014 M235i for about 9 months. I bought it with many modifications including BPM stage 2 tune, cat-less downpipe, AFE cold air intake, FM intercooler and charge pipes, clutch masters lightweight aluminum flywheel and FX350 clutch.

I suspected I'd be in for some surprises...

I just had to replace the (totally worn) clutch (went with something more modest). This was done while I was on vacation, so the cart sat for a couple weeks. One day after I started driving her again I threw a CEL, the car was idling roughly, stuttering and lurching, and is at about half the power output that she usually has (only putting out about 200 HP). It feels very much like the turbo isn't dumping.

I've been chasing OBD codes, and have replaced my MAF, and both MAP sensors. When replacing the MAPs I noticed that the signal wire from the charge pipe MAP is jumped to the signal cable of the intake manifold MAP sensor. The charge pipe MAP also has it's ground jumped to the engine bay ground. I have contacted both AFE and BPM and neither say that any sensor-jumping is required. The previous owner is also unresponsive.

When I disconnect these jumpers I receive the message: "Drivetrain Malfunction, drive moderately, maximum power output not possible", but the car just dies instantly. Any ideas why these sensors would be jumpered?

The car is currently throwing P00BD, and P0172 (I know these are only moderately helpful, not being bummer codes), and the turbo still doesn't seem to be boosting. I have plans to take it to a BMW specialist this week, but I'd still like to solve it myself, if practical.
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      07-28-2019, 09:04 PM   #2
XutvJet
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Search Google for "TMAP ground bypass". Chances are this car had a JB4 prior.
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      07-29-2019, 08:15 PM   #3
Poochie
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It sounds someone using a JB4 accidentally fried the original ground wire for the TPMS sensor and vehicle's direct ground as a substitute.

You might need to rewrite the entire ECU to fix this properly.
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