BMW 520 Auto Touring Power Loss - HELP! - BMW Forum

kolo · 08-17-2009, 01:34 PM

Hi,

I have a 2000 BMW 520i Auto Touring and have a problem! When driving on longer journeys on the motorway, usually about an hour into the journey the car seems to just loose power and just fails to accelerate. For example I will be driving at 70mph in cruise control and for no reason the car decelerates to between 40-50mph, bearing in mind the accelerator pedal being flat to the floor, the gears changing normally and the rev counter behaving normally. I normally pull off and switch the car off, wait a couple of minutes, switch it back on and it seems to solve the problem.

Any ideas of what it could be?

darkhorse737 · 08-17-2009, 02:41 PM

Quote:

Originally Posted by kolo

Hi,

I have a 2000 BMW 520i Auto Touring and have a problem! When driving on longer journeys on the motorway, usually about an hour into the journey the car seems to just loose power and just fails to accelerate. For example I will be driving at 70mph in cruise control and for no reason the car decelerates to between 40-50mph, bearing in mind the accelerator pedal being flat to the floor, the gears changing normally and the rev counter behaving normally. I normally pull off and switch the car off, wait a couple of minutes, switch it back on and it seems to solve the problem.

Any ideas of what it could be?

how about you try WITHOUT cruise control... do you have the same problems? :-)

No more problems: then cruise control circuit;
Still same problems: then possible faulty throttle electrics or intake leak

let us know ;-)

kolo · 08-17-2009, 03:04 PM

I have tried it without cruise control and it happened; bearing in mind that it is quite random when this happens - only really happens about 1 in every 3 long journeys.

Additionally, every time I start the car I need to let the engine run for approx 2 mins for the car to accelerate efficiently. If I try to drive before the 2 mins, the car struggles to accelerate (even with the accelerator pedal flat to the floor) but after 2 mins the car drives perfectly... both problems appear to be related.

kolo · 08-17-2009, 03:07 PM

When I got the car MOT'd, the mechanic mentioned that it might just be the transmission fluid needs topping up but the gear changes are fine?

darkhorse737 · 08-17-2009, 03:59 PM

glad you found the problem :-)

Regards

kolo · 08-17-2009, 05:18 PM

I still dont know what it could be? Could it be what you said.. intake leak or throttle electrics or just simply the transmission fluid - the gears seem to be fine though so im unsure of it being that?

darkhorse737 · 08-17-2009, 05:27 PM

Quote:

Originally Posted by kolo

I still dont know what it could be? Could it be what you said.. intake leak or throttle electrics or just simply the transmission fluid - the gears seem to be fine though so im unsure of it being that?

Your tech could be correct. More so if u see red oil dripping under your car.

Check tranny fluid(and make sure it is manufacturer spec A/T fluid). Low tranny fluid will can cause the symptoms you complain of :-)

easy things first, and hope everything will be fine.

Let us know ;-)