[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?

 

[darkhorse737]

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?

:gulp
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]

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]

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]

glad you found the problem

Regards

 

[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?

 

[darkhorse737]

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 ;-)