Rough running

[sledge-hammer]

Hey folks, E30 M40B18 running rough only when up to operating temperature, then gets progressively worse, pulls well on the road with no power loss but splutters and hesitates when pulling away from a stop and idles rough, you can here it popping at the exhaust and missing slightly even with revs brought up though.

Replaced spark plugs, ht leads, coil, fuel filter, put injector cleaner through system

Checked/cleaned air mass, filter, temp sensor, ecu live data & codes, emissions, distributor & rotor arm. And checked thoroughly for air leaks.

Really struggling here, any help is massively appreciated and I'll owe whoever solves it several beverages

Cheers, Sledge

[DaniTD]

Welcome to the shitty gets-worse-as-it-warms idle of the M40. Been 5 years trying to fix that, and I'm not the only one. Waiting for my oscilloscope to arrive to check ignition... Seems like this idle problem is a common fault of the M40. Mine at idle doesn't have a constant purr on the exhaust, seems like it increases and decreases flow with no variation of the idle speed (checked with DIS). Maybe some pop here and there every 10 seconds if he likes...

[sledge-hammer]

Cheers for the reply, you'd think it was the ICV but I don't know about yours but mine still hiccups slightly even with the revs brought up, don't notice it on the road though