desertfox65

I checked my idle RPM it seems to be the same irrespective of the fact whether the air conditioning is on or off. I tried to find BMW spec for idle rpm in the manual and on TIS. There is no mention of nominal specs under these condition.

Can someone advise if there is an issue. BMW recently replaced my compressor.

thanks....

5FOUR5

Ideal idle rpm after warmup should be 750

desertfox65

Is it the same with the aircon on ??

Krozi

I know on my 545i the idle with AC on was 500rpm. With AC on, it was about 800rpm.

Persian_535i

kind of random but since we're on the topic of AC, is there an option on IDrive to not have my AC turn on automatically when I start the car up?

5FOUR5

With the compressor energized and cycling at idle, there is more parasitic loss, however the loss is minimal on a progressive linear scale. Are you concerns related to the loss of horsepower, or are they more related to the operation of the compressor?

desertfox65

no I am not concerned with loss of HP. It seems that with aircon on in idling ( at traffic lights or stationary) there are vibrations on the steering wheel.It seems the rpm remains consistent at 700=/- 10 rpm. In my experience with my old E46 with M54 engine it used to be higher once the aircon is running. I am not sure why in the n52K engine it does not increase with the air conditioning running.

desertfox65

[quote name='Persian_535i' date='16 April 2010 - 10:46 AM' timestamp='1271385978' post='1153835']
kind of random but since we're on the topic of AC, is there an option on IDrive to not have my AC turn on automatically when I start the car up?
[/quote
no you cannot. you can, however press the start button twice before pressing hte brake paddle. THe car will be fully on and you can switch air con off before depressing the brakes to start the engine...

5FOUR5

The vibrations from your steering wheel could be the result of motor mounts going bad. In regards to the variances in rpm, they are all ecu related. Differnces in rpm during ac operation is just the way the ecu compensates for any given conditions. The m54 and the n52k are two different motors, i6 vs v8 therefore are running under different parameters. In continuation, our only true answers may lay within the stringent emissions stanards set upon manufacturers. This is clarly the case evev within the bmw family. We all see bmw taking the performance level away from employing more cylinders in favor of turbo charging technology, its all emissions related...

In the honda world, I've built turbo charged b20 vtecs in excess of 420 horses, and to the owners surprise, with proper tuning, the vehicle gained +12 mpg. Same goes for my j35 frankenstiens THEY GET 42 MPG!!??? its all in the ecu tuning, unfortunately, manufacturers have to consider emmissions standards now.