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Stroker1 Stroker1 is offline
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Car: 2007 e92 335i
Default 2cf6, 2cf7 hard fault. limp mode - 06-09-2019, 03:19 AM

Had a sudden, permanent issue a few weeks ago with my 07 335i. Mods include jb4 with race back end flash, comp IC, CP, WMI, 200k miles.

Stopped in a turn lane in Atlanta which was experiencing an unusually early first heat wave of the year, the dreaded limp mode logo came up on the I-drive and the dme drove to open loop.

Reading codes showed 2cf6, "throttle valve pot 1, plausibility with regard to air mass ". Car continued to operate with a very non linear throttle response and of course no boost.

Limp mode cleared when ignition cycled, but returned a couple seconds after car started. Read fault again, this time 2cf7 "throttle valve pot 2 plausibility with regard to air mass".

I reset adaptations with no effect. Fault was hard and permanent.

I logged the start cycle and upon examination, the log showed the throttle and pedal reporting position as normal.

Based on that, I replaced the in manifold MAP sensor, thinking the since the throttle position was reporting, the throttle body must be ok

When replacing the MAP sensor did not fix the issue, the other likely component, the throttle body was replaced. I again reset adaptations.

Replacement of the throttle body resulted in a good repair and car returned to normal operation.

The in manifold MAP sensor can be checked by checking voltage across the signal output and ground of the MAP sensor when the car is running, I found approximately 3vdc with engine off ignition on, app 1 vdc at idle, and 3+vdc as I blipped the throttle. I could not check this under boost, but I think it safe to assume that as manifold pressure rose above atmospheric, the voltage rises toward 5vdc. 5 vdc is the source voltage.

Not sure if a shout out to FCP is allowed on this forum, but I found the VDO branded throttle body there for less than half the price of the BMW branded unit. I think it safe to assume the units are identical and VDO is the OEM.

Checking the variable outputs on the throttle body yields no result, as the outputs are derived from a hall effect position sensor which yields no results without a voltage source. The throttle body motor will show a resistance of approximately 6 ohms.

I am submitting this as I have benefited numerous times by searching this forum for information. A search of these fault codes shows up many times with no permanent solution. My situation was somewhat unusual, in that the fault was hard, recurring and permanent. There are several similar issues noted in threads where the issue is intermittent and not hard faulted. This makes my situation easier to diagnose and resolve. But since my resolution was positive I thought someone may benefit from my experience.
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Dave @ BMS/Fuel-It!'s Avatar
Dave @ BMS/Fuel-It! Dave @ BMS/Fuel-It! is offline
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Default 06-10-2019, 08:56 AM

Thanks for sharing bro!

Glad it worked out



http://www.fuel-it.biz/

e92 AT 335xi 2.0
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