HELP. m40 idle problem (updated with video)

Post Sat Jun 10, 2006 12:18 am

Can anyone diagnose this idle problem?

from cold, after 1st start, the engine almost stalls, then runs up to about 900 then slows to almost stall again.

The ECU has a type 3 zone chip and the engine is apparently running a weak mixture.

Post Sat Jun 10, 2006 12:46 pm

i would say ICV...

m

Post Sat Jun 10, 2006 8:38 pm

i've had this problem with my old 316i more than likely the idle control valve also the pipe that runs into the valve at the bottom get old and brittle and leaks, a new pipe solved half the problem with mine and a second hand valve solved the other half

a bentley manual tells you how to check the valve

Post Mon Jul 10, 2006 11:07 pm

I have cleaned the ICV and TB with carb cleaner, as well as the inlet manifold.

Now the idle is WORSE

now it jumps between 2K and stall

im waiting for a plastic insert for the rocker cover, to see if that makes any difference.

Post Mon Jul 10, 2006 11:33 pm

i've got a cover bt ur bit far away m8 u cud av had it

Post Mon Jul 10, 2006 11:34 pm

TPS (Throttle position senser)

This will happen if you have adjusted the idle screw

Post Mon Jul 10, 2006 11:37 pm

jonbuoy wrote:TPS (Throttle position senser)

This will happen if you have adjusted the idle screw

nope, dont think its that. already tried 2 different TB's

Post Mon Jul 10, 2006 11:38 pm

essexboy wrote:i've got a cover bt ur bit far away m8 u cud av had it

thats okay. m-dtech is sending me one.

Post Mon Jul 10, 2006 11:39 pm

Have you tested if you can here the click that the throttle body make's whilst the engine is not running?

Post Mon Jul 10, 2006 11:40 pm

next step is to remove the zone chip and see if that fixes it. although the idle was fine when i first installed it.

Post Mon Jul 10, 2006 11:40 pm

jonbuoy wrote:Have you tested if you can here the click that the throttle body make's whilst the engine is not running?

1st thing i checked.

Post Wed Jul 12, 2006 12:29 pm

ANYONE ?

Video of tach when cold.

http://www.youtube.com/watch?v=3zTKmxBAfX8

Post Wed Jul 12, 2006 12:41 pm

smithy318i wrote:the engine is apparently running a weak mixture.

Seems like an air leak to me. Mine runs very weak on idle but not upon acceleration/cruising. I ran out of things to check after a while. changed sensors the lot. It could be that your AFM is not calibrated properly?

i would check air leaks firs though, the old wd40 trick

Post Wed Jul 12, 2006 12:49 pm

WD40 trick had no effect at all.

Post Thu Jul 13, 2006 12:40 am

You say you've cleaned the ICV, but have you changed it?
Only thing I've ever had that was anything like the video was caused by a dud ICV.

Post Thu Jul 13, 2006 12:46 am

Brianmoooore wrote:You say you've cleaned the ICV, but have you changed it?
Only thing I've ever had that was anything like the video was caused by a dud ICV.

i have replaced it with another one that i had off a breaker.

how can i test the ICV ? it seems to be working okay when i pass 12 volts through it.