Hello All....I need help...my ultimate driving experience is being ruined!
I have a 2007 650i convertable Auto with 65000 miles on the clock.
I am having a problem with this car and its split personality.
This car sometimes drives like a dream. The accelerator will nice and light and responsive, the car glides over bumps in the road and speed humps without so much as a ruffle, as if riding on air, the steering is light but responsive and the overall car feels light, crisp and responsive and a real pleasure to drive...then all of a sudden for no apparent reason it will start to drive like a dog, which is most of the time.....the accelerator will feel stiff and heavy and unresponsive, the actual acceleration of the car becomes diminished, unresponsive and underpowered. The car will go over bumps in the road and speed bumps as if the dampers have been turned off and the shock absorbers removed, the ride will be rough, the steering will feel heavy and labouring and car will just feel like a big lumbering lump.....then i might stop at a shop....turn it off..get back in and start it and it will drive like a dream again, for a time....but sure enough, it won't be long before she is back in dog mode, lumbering around the place and being totally unresponsive like a big wet fish.
Basically when i get in this car and start driving, i never know what car it's going to be....there are rough roads and speed bumps leaving my house, and everytime i leave i wonder whether i am going to glide over these things, or get thrown about and have to go over them considerably slower than i should have to. If i start the car and leave it to idle for 10 minutes or so, then drive it, it will always drive nicely to start with. If i get in and start it and drive off, i am not sure what behaviour i will get, it's usually the dog kind.
The car has been recalled to have a "battery lead checked", which i haven't done yet, but i am sure it isn't that causing the problem...although sometimes the way i would describe what happens when the car starts to drive correctly, is like someone suddenly turning on the electricity and the car comes to life...and i only need to barely touch the accelerator and she is responding like a jet...and the steering becomes light and responsive and the car becomes nimble and agile with a beautiful smooth ride and effortless acceleration, making light work of any bumps in the road, as if they are not there. This is how the car should drive!! But it is not often what i get from the car...
Also, when it is running like a dog, it seems to have a flat spot accelerating between 1000 and 1500 rpms when the car is in motion, not from a stand still. So imagine you are accelerating and reach maybe 30 mph, then you come off the accelerator and the revs drop as you are freewheeling, when you go back on the accelerator there will be a flat spot and the exhaust will make a rumbling sound for a second or so, then it will start to accelerate. This doesn't happen when the car is driving properly.
Please, has anyone experienced this before or have any idea what could be causing it? I know there is safe mode that these cars can go into, but there are no lights or signs of this...the only light on the dash is a seatbelt light, telling me there is a fault in the restraint system, which there isn't as the seatbelts work fine. I think this light is faulty.
I have been told my problem may be a crankshaft or crankcase sensor, mass air flow sensor, coil pack, throttle position sensor or crank case pvc valve.....I had someone put his computer on it a while back and no codes came up. Maybe i need a proper dealer to put it on thier computer and see if anything comes up.
Please, please, please...someone must know what is going on with this car.....it needs to be sorted.