Z4MC Intermittent Fault

[FarmerP]

Has anyone had a problem with their Z4MC where it doesn't pick up smoothly when you back off the throttle? It's very hard to describe and replicate but if you're cruising at 70mph and back off for a few seconds, then accelerate again, the car falters quite noticeably for a second or two and then clears itself and is fine. It is the only time it does it but it doesn't always do it either! I popped it into the dealer as I've still got a few weeks of warranty left and they couldn't find any fault codes. Does anyone have any suggestions?

[mmm-five]

Not had anything like that on mine, but then I'm rarely cruising at 70mph or backing off

Edited by mmm-five on Monday 4th May 18:43

[ian in lancs]

Not had that on my Z4MR. It doesn't run smoothly when cold but once warm its fine. The dealer says 'they [with that engine; M3, Z4M's] all do that sir' so I'm not bothered. I assume as you're doing 70 odd its warmed up.

The things it could be are ignition related; coil packs or spark plugs and these would create fault codes from unburnt fuel - lambda failure and a warning light or fuel flow / pressure related and I assume as its running fine otherwise it wont be that.

Probably nothing other than the response time of the engine from fuel/igniton off on the over-run to the fuel/ign on demand again.

[FarmerP]

Thanks Guys

I've booked into the stealers again because I'm not convinced everything is right with it. It was playing up doing 30mph the other day (I was in a 30 limit by the way!) and it's becoming more noticeable. I've tried different fuel too and that makes no difference, I was going to try some additive to see if that cures it. The bizarre thing is the way it runs perfectly smoothly the rest of the time and still goes like a rocket - pulling onto motorways is sooo much fun...! I'll keep you informed of progress - it's not booked in until the end of May though, and no chance of a courtesy car until June!