My wife's '15 X1 (4 cylinder w/turbo, 65K miles) sometimes surges for like a half second sometimes right after she's backed out of the garage and started to drive away. It just happens one time - like the gas pedal was pressed down for just a half second or so. It never does it if the vehicles is warmed up, and it doesn't do it every time even when cold, just sometimes. The car is maintained pretty well, in fact it just had a major service around 2 months ago. Any thoughts on what could be causing this? Thanks a lot.
It could be anything, but often BMW has software updates to the engine computer (DME) that fixes minor behavior issues like that.
-Abel
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The first step in diagnosing a problem is to scan the engine computer (DME in BMWspeak) and the automatic transmission computer (EGS) for codes. The Service Engine Soon light is on only when an emissions related code is present. Find a reputable indie shop that specializes in bimmers at www.bimrs.org. A good indie shop will have the computer software to properly diagnose the issue and update the software, if needed.
When we get customers with this type of complaint and the technician can't find anything wrong with it, we put this in the notes on the repair order :
Note: **Be sure the vehicle is stopped completely and allow enough time for the transmission to completely finish shifting into the selected gear (about 1 full second) before releasing the brake pedal.**
If you shift from Reverse to Drive while still rolling even a little tiny bit, or if you let your foot off the brake before the trans is fully in gear, the RPMs can "surge" a little.
You didn't mention how much it's surging, though. The above usually results in a little 200-ish RPM "surge".
Not sure how much the surge is RPM-wise, but it's enough to make the car jump ahead for a second or so, like it suddenly got a little boost of power. This happens while going through the parking lot at prolly 5-7mph.
I've relayed your info to my wife and we'll see what happens, and will mention it to our tech next time we're in. We both appreciate everyone taking the time to help - thank you.
This is likely the car shifting from 1st to 2nd at low speed and low throttle input. You can test it someplace away from other vehicles by putting it in 1st gear in manual mode and driving at about 5mph with very little throttle input and shifting to 2nd, and see if that's the same feeling.
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