I'm new to the M5 and I have an idle problem when the air conditioning is turned on , the idle will jump to 2,500rpm , when the air conditioning off the idle is 900-1000rpm. Some searching online indicates it could be a dirty or blocked ICV but where is it ?
I've searched all over the internet and can't find any photos or diagrams.
Pop off the airbox and air accumulator and you will see the sea of vacuum lines running around down there. While you are cleaning out the ICV, be sure to inspect those vacuum lines. They are often very worn and cracking.
I found this online which gives very clear step by step instructions for removing the intake plenum which maybe useful to other new owners (this is old hat to the veterans )
P.S. One of the things I don't like about working on BMWs so far is the endless plastic clips and tabs, some of which were designed by Mr Rubic I think (of Rubic's cube fame). They seem to have their own special techniques required to get them out without damage.
Blocked or dirty ICV would result in low idle speed. The flare with AC activation is more likely to be a low AC system pressure; the ECU is expecting an AC load to arrive when you turn it on. The ECU opens the ICV valve more (its allready open to control your base non-AC idle speed) to allow more air into the engine to offset the higher load due to AC. With low AC system pressure no additional AC load actually arrives and you get an engine flare.
When they filled the air conditioning on saturday they used 3 small cans of refrigerant , I didn't notice the system pressure , when I checked online later on Saturday night I noticed that a full charge should be in the range of 1.2 to 1.4kg. I think the cans of refrigerant would be half that.
The air conditioning belt is also suspect so that needs to be changed , I had a few belt squeals this morning.
The AC is blowing ice cubes when it's on , very cold.
I've been using the AC at cruise speeds and when the vehicle is moving as I can control the rpm when the M5 is in gear to normal levels. It's idling in traffic that's the problem.
I'm going to have to use the local BMW dealer , these local shops are a waste of time.
My local independant is good for this kind of thing... Weighs the stuff out and in.
Regarding low pressure/mass, I am pretty certain that the low pressure switch that protects the pump also stops the idle offset coming on. If you have cold air... Leave it alone.
When they filled the air conditioning on saturday they used 3 small cans of refrigerant , I didn't notice the system pressure , when I checked online later on Saturday night I noticed that a full charge should be in the range of 1.2 to 1.4kg. I think the cans of refrigerant would be half that.
The air conditioning belt is also suspect so that needs to be changed , I had a few belt squeals this morning.
The AC is blowing ice cubes when it's on , very cold.
I've been using the AC at cruise speeds and when the vehicle is moving as I can control the rpm when the M5 is in gear to normal levels. It's idling in traffic that's the problem.
I'm going to have to use the local BMW dealer , these local shops are a waste of time.
The M5 came out of a 4 day check up in the dealer , the air conditioning problem (2,000 to 2,500rpm at idle with air cond on) turned out to be the wrong size belt. It didn't make any noises for 7 weeks , it was only the last week that it started squealing , belt was too long and not the right profile , it was too wide and not seating into the pulley properly.
I now have fully functioning air cond which is great as today was a hot one , I had to turn the air cond right down this evening as it was too cold
Belt? Not sure i see how the belt would effect idle speed, the ac load isn't that great. I had the same problem with ac and idle speed and it was a bad throttle switch.
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