Misfire at 2000rpm

[JohnLC]

Hello, my 20 year old 3 series estate (E91) has 93,000 miles on the clock. There are no codes detected at a BMW specialist's garage but there is a slight but noticeable stutter on acceleration. It happens when the engine reaches 2000 rpm in all gears. The vanos solenoids have been replaced, a new fuel pump fitted, new ignition coils and spark plugs. All the injectors have been cleaned and tested. A smoke test for leaks has been done-none discovered. Can anyone think of any other checks that can be done without breaking the bank?

[Greydog]

Hi John

Welcome to the Forum

I would check very carefully the loom to the coil packs and the Injectors. I have seen a misfire fault on a Volvo T5 and a BMW 335i neither car logged fault codes. Both cars would start and run smoothly and show no fault or misfire even when revs were raised, but if the car was under load the symptoms were there. The T5 it was injector harness with cracked insulation and the BMW failed insulation on the loom to the Coil Packs 

Hope this helps 

Dave

 

[JohnLC]

35 minutes ago, Greydog said:

Hi John

Welcome to the Forum

I would check very carefully the loom to the coil packs and the Injectors. I have seen a misfire fault on a Volvo T5 and a BMW 335i neither car logged fault codes. Both cars would start and run smoothly and show no fault or misfire even when revs were raised, but if the car was under load the symptoms were there. The T5 it was injector harness with cracked insulation and the BMW failed insulation on the loom to the Coil Packs 

Hope this helps 

Dave

 

Thank you, Dave, this is just the sort of advice that I'm after and you have summed up the symptom perfectly. I've just been into Halliwell Jones (BMW North Wales) and they're looking for £156 per hour for a diagnosis! So any advice is welcome.