My car is going nuts
 

I’ve had similiar trouble on the 08 4.8i before and checked the wiring harness, tested another thorttle body, chnaged the gas paddle and it ended up being the battery. However now the battery is holding charge fine. Here are the nuts symptoms: Car started going into limp mode but no errors, simply i mashed the paddle and the car would not accelerate, had to turn it on/off and it would be a while till the car went into limp mode, still no errors. This sometiems did and sometimes didn’t happen. These days it went in limp mode and i got the 4x4 malfunction and various warnings, cruise control malfunction etc. Today the really nuts behavior re-accured: the car started bucking forward, without me giving it gas, it stalled, the rpms kept going up and down and i could barely drive it. Left it sit and the car started back up no issues, last time i checked here are the codes: 2CF8 throttle potentiometer, 2CF9 throttle potentiometer 2, 2CFA throttle potentiometer 3, 2D32 differential pressure sensor plausibilty error. These come up when the engine malfunction light comes up. It probably had more codes but they got erased as the car has been from shop to shop and they’ve got no clues including the BMW dealer. They’re advising i try changing the throttle body. Any ideas ?


Here is a video of it going into limp mode without any warning, and after a turn off/on: https://youtu.be/DLWsDDoCulg

Just a guess but it might be the DME unit (the brains of the engine--controls every calculation in the engine). I had mine replaced luckily in April 2016 (there is an 8 year warranty on them from BMW). The failure rate on those is really, really low though--like 1 car in 300 they go bad.

Thanks for the suggestion. I would not doubt that this isn't the 1 in the 300, i will have to check. Do you know where the DME is located? Why did you have yours replaced?

I'm not sure where it's located. My car shut down on the freeway and threw up a bunch of codes--that's all I remember specifically.

Same issues in the past changed a used throttle body on eBay 20$ gas pedal and throttle body harness easy check xoutpost for diy

Really? You had THE SAME THREE CODES?????

1 in 300? That's a recall

Try one in 10,000

id be hard pressed to suggest he chase after DME issues .

OP, how do you know the battery is good? 'Holding a charge' is not a great test. If the car did the same things before, and that was a bad battery, it would seem easy to rule out a battery. Like 200 euros easy...

Just changed the throttle body again yesterday, same issue however it did not go erratic, but that happens only sometimes after going into limp mode and the car kept throwing the same errors. The harness they're calming is not the issue, but i'll have to check that again.

Well the first time the battery voltage would drop to 9 volts when starting the car. Why i'm sort of ruling the battery out is because it's been changed about a month ago and the issue was gone after that. I find that very strange that the same errors went away for over an entire month, and i drove the car everyday. :dunno:

9V sounds a bit low but don't forget your starter motor draws *a lot* of current, which will lead to a temporary voltage drop.

I didn't say it was the DME--it was a suggestion as he said so many codes came up he didn't have them all written down. The 1 in 300 DMEs is all BMW model DMEs not just X5--per the dealer that had to replace it.