M42club.com - Home of the BMW E30/E36 318i/iS

DISCUSSION => Engine management => Topic started by: DC on March 28, 2013, 09:02:34 PM

Title: M40 AFM Compatible with M42?
Post by: DC on March 28, 2013, 09:02:34 PM

My M40 engine in my e30 suffered irreparable heat damage to the engine block so I decided to replace it with an M42 from another e30.
Unfortunately due to some miscommunication the engine dealer did not ship me the M42 Air Flow Meter (M42's are rare in Australia and he is in another state).
He's now offering to ship it for an additional fee, but I'm wondering if I can just use the AFM from my M40?

The M40 AFM looks (to me) identical to the M42 unit, but some research reveals that the M40 uses Motronic 1.3 while M42 uses Motronic 1.7.
The AFM's have different part numbers, but after an extensive search on the internet I can't find definite proof that they cannot be used interchangeably.

Can anyone help me clear this up?

Title: Re: M40 AFM Compatible with M42?
Post by: fabe on March 28, 2013, 09:22:33 PM

I think I have tried it, the M42 engine ran fine with the M40 AFM but then I didn't use it for long term...

Title: Re: M40 AFM Compatible with M42?
Post by: DC on March 29, 2013, 07:37:38 PM

Thanks for the reply. Some e30 owners in another forum have told me it's worked for them too so I'm going to take a wait and see approach and assume it will work.

Title: Re: M40 AFM Compatible with M42?
Post by: M42Power on June 11, 2013, 12:15:09 PM

Hey, if your m40 was a b18 then the afm is exactly the same. It even has the same part number. If it was a b16 then you're going to need another one.