BMW M40 idle...

Post Tue Dec 07, 2021 4:17 pm

So, my E30 M40 last night stalling in traffic when idle. Then I start up engine again and idle is perfect. Also today, idle is perfect.

Sometimes idle is great for a long time than again, I have problem like last night. Start engine again and everything is normal.

ICV is clean, MAF boot is new, hoses under intake also new. Vacum hoses also. There is no vacum leak.

Is it possible that problem in ECU/Motronic in the term of age ? Which sometimes can make problem with idle ? Also MAF and ICV with purely mechanical problem which occasionally affects on idle.

Post Thu Dec 09, 2021 12:14 am

Just because your ICV is clean, doesn't mean it works. I'd try a new one. There are inexpensive aftermarket ones.

Post Thu Dec 09, 2021 6:29 pm

twright wrote: ↑
Thu Dec 09, 2021 12:14 am
Just because your ICV is clean, doesn't mean it works. I'd try a new one. There are inexpensive aftermarket ones.

I was thinking about that.

Idle last day and today was perfect. But just like I said in first post, suprise with stalling is posible...

Post Thu Mar 24, 2022 8:05 pm

I think that I solve this problem. Problem was insidiously vacum leak on brake booster hose. I put new hose in January and to this days, idle is fine.