M40 owners only please.

[smithy318i]

Hello fellow 4 pot "wrongness" owners.

Im trying to sort a few anoying little problems out, but I dont know if my engine is running right or wrong.

Can you tell me what your idle speed is when cold, and does the idle speed pulsate ?

If you dont know what i mean, please watch this...



and

[Wookie]

My M40 idles at around 750 - 800rpm - but never "pulsates". Rpms jump between 750 and 800 rpms but have never pulsated as bad as yours Smithy!

[E30Mark]

My new acquisitions idle is rock solid @ 750rpm regardless of temp, with 185k on the clock!

[Jos]

850rpm ish at idle when warm 900 or so when cold

yes it pulses from time to time, normally about 50rpm or so. No idea why though but then again it doesn't bother me that much. No where near as much as that and its a very regular pulsing of about 2 second interval. 167k on the clock and running well (0.82% CO and 168ppm HC)

[stuartgallafant]

smithy, by pulsate, i assume you mean "hunting". at least thats what its called in the 'industry'

usually this is down to an air leak of some sort. being an M40, im thinking it could be either intake bellow has split, inlet manifold gaskets or some of the rubber piping around the ICV or anywhere for that matter

however, i have known a few AFM's to cause the same issues

HTH

[stitch-626]

the mummy wagon idles 900ish whan cold (this morning) does pulse abit but i know that i need to replace my afm,
when we first got the car the afm was well fooked so swaped it for a freeby and that solved it for a while. i'm gonna check all the pipes just in case might be an idea for you to do cos i had 3 afm's on the beast before i found out that it was one of the pipes (sods law)

[Gwynleym10]

My old SA m40 did that, it eventually died at traffic lights when it was really cold etc.

However the ICV that you sent me solved it.... Did you ever try that ICV on your car?

I no longer have the car so can't really help any more.

Have you made sure its all sparkley clean?

[smithy318i]

Its getting worse
Now it idles at about 500 and stalls repeatedly when cold.

It could be the rubber ring at the base of the TB at fault causing a leak.

ICV is clean (did it at the same time i did yours)

[318i1989]

my M40 1.8 does the same thing so it seems you're not alone. Mine hunts around between 600rpm and 800rpm at tick over and feels like it's going to stall think it may be AFM too

[jcjdavis1]

Hi my M40 sits at 900 when cold,700-800 when hot