Idle problem when braking/down shifting

[CTCRM]

Can anyone help me? I Have just bought an 2001 auto X5 4.4i sport with 68,000miles on the clock. I have noticed when braking from around 40mph to stand still at a red light that the car revs seem to drop just a tad below the 500rpm white line, causing the car to vibrate/shiver for a split second. The car doesn't have to be stopped for it to do this, it also does this when down shifting on moderate braking, at low speeds 25-15mph, again their is a slight vibration/shiver.

If i let the car slow down by itself, (without braking) the car doesn't vibrate/shiver

The car is not displaying any warning lights and the engine feels very smooth when drving normaly.

The car is about to go to BMW service for its oil change at the end of this month.

The car was plugged into a computer and no faults found, the Idle was increased by 50+rpm, but this has not helped

I think the gearbox may be holding onto the gears for a tad to long when down shifting.

Does any1 know if this may be cured by a software update, or is it some sort of sensor not working????

Thank you

[CTCRM]

[Wagner]

That's right, we're all boycotting you

Now backing off your tude, here is part of your problem. Probably something to do with your idle sensor on the motor, this is why it sounds less when the AC is on. When the AC is on the RPMs are increase by about 200, which makes up your difference as smooths out the idle. You'll need to take it to a dealer and have it diagnosed. As it is an older model, it could be multiple things.

[Sudesh]

I cant say exactlly what it is but the reason it idles better when Aircon is on is because Aircon drives the revs up!
Seeing as you just purchased the X, I would have the air/intake filter changed, do the spark plugs and to be on the safe side have BMW do an oil and gearbox filter change when it goes in for service as there have been quite a few recent reports on the gearbox giving up.
The airfilter you can do yourself and its cheap. The plugs are reasonably cheap and easy to do also [depending on your DIY skills]

[CTCRM]

Hey thank you for the reply, I have up dated my thread and taken out the air con bit as car still does it with air con on now, idle was increased by BMW specialist by 50rpm, but car still has the same problem. Please can you read my updated post again and see if their is anything I am missing to check.

Cheers

[Wagner]

Sounds like something to do with idle control to me.

[Sudesh]

Check your engine fan blades to make sure they are all in good condition and not cracked or broken anywhere. Also I would still do the plugs, air filter and gear box oil and filter change.