E36 - catalyst and idle question

Mon Mar 09, 2015 10:53 pm

Hi all,

I've recently picked up an e36 318is.

92 J plate with the M42 lump.

How can I tell if it has a cat? The online VIN decoder things don't come up with one.

It has a fluctuating idle, I suspect the AFM. It has a 0 280 202 134 fitted which I understand is the one without a CO pot for catalyst equipped vehicles. I think it should have 0 280 202 135 according to realoem.

Could an incorrect AFM cause idle issues? Anyone have a 135 for sale?

Cheers.

Tue Mar 10, 2015 7:14 pm

Hi Will, thanks for the suggestion.

I have sprayed plenty of carb cleaner about but no difference. I did notice the breather hose off the head is very soft though so I will replace this anyway.

When I undid the oil filler cap with the engine running the idle got worse, the dipstick didn't seem to make a difference although it is seated correctly and the seals seem intact.

Tue Mar 10, 2015 7:17 pm

the idle valve on my m44 caused loads of trouble, try cleaning it out with carb cleaner

Tue Mar 10, 2015 7:18 pm

the idle valve on my m44 caused loads of trouble, try cleaning it out with carb cleaner

Tue Mar 10, 2015 7:27 pm

If it has a lambda sensor, then it doesn't need an AFM with a CO pot. Conversely, if it doesn't have a lambda sensor then it does need an AFM with a CO pot, although with a bit of wiring rearrangement, you could fit a separate pot. somewhere else.
If it has a lambda sensor, there will be wires connecting to something that looks a bit like a spark plug, somewhere in the front half of the exhaust.