Newbie with question
 

Hi all, I have a late 96 318ti (M44) that has an idle issue. I have done alot of searching on this site and others and have found some good info. But im trying to establish if the slightly rough idle is something I just have to get used to. Im more used to 6cyl BMWs and the old M10 4cyls.

Story goes like this, picked it up and noticed a misfire type issue at idle. Replaced plugs, no better. Replaced cyclone valve, some improvement, no longer shaking, just a little rough. Took it to a specialist who ran diagnostics and told me pre cat lambda was faulty so at a cost of £145 it was replaced, however the idle is the same. The rev counter stays still, but the idle feels rough and there is a popping sort of noise at the tailpipe. My specialist says their 318is Coupe loan car does a similar thing and says not to worry. Im not worried it will break or anything, its just not very BMW ish.

So far I have cleaned the ICV, replaced the Cyclone valve and the hose that goes to it, changed the plugs and had 1 lambda replaced. There are no fault codes at all now. Any ideas? Thanks!

The 318ti's are known for a slight roughness to their idle.

Perhaps your fuel injectors need to be cleaned?

Just to chime in and let you know I have a similar issue. Sounds like a slight misfire at idle. I haven't been able to track it down yet, and am not sure if it's supposed to be considered normal, but I'm doubtful. I've replaced wires, coils, injectors, plugs, vacuum hose to the injectors, O2 sensors. I'm planning on taking out the DISA valve next, and I think the CAT may be a little wonky. The exhaust is a little noisy when the engine is cold. The engine seems to run fine otherwise.

I just dont want to get into the situation of throwing new parts on the car, ive not had to do it on any of my other BMWs to cure faults! As you say though, the car runs perfectly otherwise.