Splutter at startup

3

35isDreamer

Member
Hi
I've had my 35is about a year. 13 plate. Until last 2 weeks, it has started almost instantly the moment I press the start button and roars to life.

Last 2 weeks, when engine cold, it has sometimes taken one or two seconds to start and almost coughed as its started. Not the roaring to life. Within a couple more seconds, its fine.

Its going in soon for new brake pads anyway, but anyone got any experience of this?
 
I had exactly those symptoms last year.
They replaced the low pressure fuel pump and it's back to normal.

Wasn't easy to get them to fix it as it won't store any error codes. Had to really over exaggerate the symptoms.

It could also be injectors leaking fuel into the cylinders after the car has been turned off.
 
I've had two 35iS's where they are rough for the first mile or so ... but not bad on start up itself so I guess there is an issue. My issue with with the cold running map itself.
 
SO8 said:
I've had two 35iS's where they are rough for the first mile or so ... but not bad on start up itself so I guess there is an issue. My issue with with the cold running map itself.
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The N54 isn't the smoothest at idle.

I have increased my idle speed to 740rpm which helps quite a lot but you can still feel some uneven movement from time to time.
Plenty of people have tried to make the N54 idle smoothly but most just give up after spending a couple of grand.

My car has new spark plugs, injectors, 4 x O2 sensors, primary cats, LPFP and HPFP and it still rocks a little when the idle drops down low.

I'm tempted to just replace all the coils as that's the only part of the ignition system that is original to the car but spending £140 replacing something which might or might not smooth the idle out just seems wasteful.

People have also claimed that the PCV, vacuum lines and crankcase breather can be the root cause of idle roughness.

Given that rough idle is something that even new cars suffer from I think it's just a quirk of the engine. Very few people claim to have a truly smooth idle and I get the suspicion that they are just not observant enough to notice it :P
 
Thanks all.

It is intermittent - I'd say 70% of cold start ups. Its rough for a couple of seconds only, not an issue at idle that I can notice.

I'll see what the dealer says.
 
Update.

Dealer has found faults messages regarding fuel system. They have reset some elements of the system (not really sure what exactly) and will test over the next 24 hours. If issue still there, they will replace the high pressure fuel pump under warrantee tomorrow.
 
It sounded alright zooming up the hill the other morning Will! :)

Hope they get it sorted out for you! :thumbsup:
 
Thanks! I waved at you this morning in my courtesy red 1 series.

Note to self - never buy a small diesel 1 series. They are pap!
 
Haha! I missed the wave - apologies!
Will ensure I stay clear of any under powered diesels in the future - even if diesel is now cheaper than petrol!!
 
Oh no. Reseting the settings didn't fix the issue. And now a new high pressure pump hasn't fixed it.
So they have referred back to BMW for guidance.
The dealership is out of ideas.

Any clues to what they might suggest next?!
 
Stories like this worry me a little - 'techs' fumbling around in the proverbial dark! Has the LP been replaced too or just the HP? If that cured a similar issue for someone else it may work?
 
Scooba_Steve said:
Stories like this worry me a little - 'techs' fumbling around in the proverbial dark! Has the LP been replaced too or just the HP? If that cured a similar issue for someone else it may work?
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Worries me more than a little...

They have only replaced the HP so far.
 
Possibly,

Its unbelievable how the dealers approach a fault...

It would be easy to see if the fuel pressure was low on first start in the morning,and a smooth running test on the injectors would give a decent indication if an injector was sticking or being problematic..

Throwing things at the car with hope and little else is crazy..
 
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