E46 3.18i Noisy at start - no power neither!

Post Sun Jun 27, 2010 9:59 am

Hi All,

I have a 2000 Auto E46 3.18i...

I've never owned one before and my only other experience with BMWs was my e30.

At start up after a night parked up, no matter the weather the engine is LOUD. It sounds like a pile of poo... As far as im aware its the secondary compressor running but Is it supposed to be loud? Do other 3.18 owners get the same? It last for a couple of minutes then turns off but its so loud for that time. It just doesn't scream BMW if you know what i mean!

My next question is: During that time period i cant pull off as there'll be no power ready...it's like it has to charge. Surely the car should be able to go once running?? When i press the accelerator there is NO immediate pick up until the car is warm and even then its not as i would expect, there's always a little hesitation. The car doesn't stall, it just doesn't go when my foot goes down. Before i start forking out on expensive diagnostics do you guys have any idea why this would happen?

Any help would be much appreciated!

Jason

Post Sun Jun 27, 2010 11:30 am

I've got a 2001 318ci - different engine I think as yours will be an 8v M43 not the 16V valvetronic.

The compressor on mine when you switch the automatic air-con on is very loud and also gives the car a slight shudder when its stationary. Once the climate control has worked its magic its fine.

The second point could be the infamous M43 throttle body sticking. I had something similar on my old E36 316i - the disc gradually creates a groove in the throttle body and sticks. Sanding it down and smoothing it out usually does the trick. Don't know if the E46 set-up is the same.

Is it misfiring at all? My old 316i had a very lumpy start up and no power until you gave it a few revs. This cleared the misfire but was a sign of the head gasket about to let go. Very common on the M43 and tends to occur between 95-100K.

Post Mon Jun 28, 2010 8:24 pm

Get it scanned. Air mass meter is a VERY common cause of flat spots and poor response on these, amongst other things.

Post Mon Jun 28, 2010 9:12 pm

i think it will be your AFM, try get one from the scrappys and it give ago.

The EML wont show AFM, it will show something like Lambda bank 1 running lean, or something like that

Post Tue Jun 29, 2010 4:56 pm

Thanks for all the help Lads! - RE the afm i was told that you can unplug it and drive the car, in which case if the problem persists then its not the afm. I have done that and the problem is still there.

How do i check the engine type?

I will check the throttle body - thanks for that

No - it's not misfiring at all?

Looks like im going to have to fork out and get it scanned

Post Tue Jun 29, 2010 5:08 pm

Jay07 wrote:How do i check the engine type?

M43 is an 115'ish bhp 8v lump and more "traditional" looking (looks similar to a M42/M44). The later 143bhp 16v valvetronic is a typical more modern BMW engine - made from chocolate and hidden under horrid plastic!

Post Tue Jun 29, 2010 10:31 pm

Mine must be an M43 in that case because i'm definitely missing the chocolate!

Post Wed Jun 30, 2010 1:21 am

Jay07 wrote:Thanks for all the help Lads! - RE the afm i was told that you can unplug it and drive the car, in which case if the problem persists then its not the afm. I have done that and the problem is still there.

How do i check the engine type?

I will check the throttle body - thanks for that

No - it's not misfiring at all?

Looks like im going to have to fork out and get it scanned

You cant realy run the car with the AFM disconnected, as this will still give you a default value, and cause the car to run rough. If your car was running sweet and you disconnected it, it would start hunting. .

From what you say i personally think its the AFM