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Do you see evidence of any black smoke when the car is running rough?

Has it got worse as it's got colder?

How long does this condition last?

It's about the same as when it first played up some weeks back. It's hesitant and intermittently misfires for the first mile then starts to smooth out and is normal when warm.

I have warranty so whatever comes the max cost will be the excess.

It's just getting it to be faulty enough to show codes or risk the dealer going 'seems fine to us' because there aren't codes.

It's just had a full service including plugs so it's not those (provided they really did change them).

And no, no smoke of any kind.

So to help my in my diagnosis can someone with a 35i/s start their car, let the revs settle to around 600r at idle as normal and then try and hold the throttle at 1000 or 1500 rpm (no higher).

I can only stabilise revs at 2000rpm or higher. Lower than that results in the idle bouncing up and down if I try to hold idle around 1000 rpm.

This will help me understand if the rev bounce is normal at light throttle when stationary or if it's a symptom of whatever is wrong.

Here is what I mean. For some reason I've also acquired a nice loud whine this morning from the engine, I'll consider that coincidence for now as it could be belts with it being stood a while.

So in this video I press the throttle a tiny amount and hold it there with my foot wedged against the footwell wall. I can't keep the revs stable until they're well over 2000rpm and I've no point of reference to indicate if this is right or wrong.

It just sounds and feels wrong.

https://youtu.be/SJsdVjejGjg

Chances are that its going to be an injector.

I would get it in for diag check as a smooth running test can be done and this can determine which injector is faulty... On the N54 batches of 3 injectors should be swapped due to indexing.

What happens is the injector starts to drip fuel onto the top of the piston,effectively flooding the cylinder until it can be got rid of through combustion.

What you DONT want to happen is the injector to stick fully open and fill the cylinder,upon start this hydraulics the piston and will bend the rod. Sounds drastic but it does happen,and it aint rare..


I wouldnt wait....

Maniac wrote: ↑Sat Sep 16, 2017 12:54 pm Here is what I mean. For some reason I've also acquired a nice loud whine this morning from the engine, I'll consider that coincidence for now as it could be belts with it being stood a while.

So in this video I press the throttle a tiny amount and hold it there with my foot wedged against the footwell wall. I can't keep the revs stable until they're well over 2000rpm and I've no point of reference to indicate if this is right or wrong.

It just sounds and feels wrong.

https://youtu.be/SJsdVjejGjg

Just uploading now!

dario wrote: ↑Sat Sep 16, 2017 3:37 pm

Maniac wrote: ↑Sat Sep 16, 2017 12:54 pm Here is what I mean. For some reason I've also acquired a nice loud whine this morning from the engine, I'll consider that coincidence for now as it could be belts with it being stood a while.

So in this video I press the throttle a tiny amount and hold it there with my foot wedged against the footwell wall. I can't keep the revs stable until they're well over 2000rpm and I've no point of reference to indicate if this is right or wrong.

It just sounds and feels wrong.

https://youtu.be/SJsdVjejGjg

Just uploading now!

here is mine (35i)



Sorry about the de-mister

Thanks for that. So I saw a little bounce in revs when you held it at 1000 but it seemed to settle. Mine doesn't, it continues to bounce up and down despite holding the pedal at a fixed position.

Looks like this is an easy way to point at a fault.

Maniac wrote: ↑Sat Sep 16, 2017 3:57 pm Thanks for that. So I saw a little bounce in revs when you held it at 1000 but it seemed to settle. Mine doesn't, it continues to bounce up and down despite holding the pedal at a fixed position.

Looks like this is an easy way to point at a fault.

Have you got any damage to any air hoses (vacuum system) this was a typical symptom in my past of cars with air leaks on the inlet manifold.

one way of finding a leak is to use brake cleaner (be careful) if the engine speed increases in an area when sprayed than its sucking in to the manifold at that point.

just a thought.

Hi Manic,

on a different point what code reader are you using and is it any good.

I need to clear my airbag light on my 5 series GT F07 and the dealers want £30 with is a good price IMHO, but i'd like to put this toward a reader/ fault clearing device as with my Z4 and F07 and my daughter cars, adding another £40-50 might be a better idea as then i'll be able to read and clear faults on all cars (i think)

cheers

Nothing im aware of. It's only an issue when cold.

It's warmed up now and revs can be held at 1000 with ease.

When cold I get that bounce as per my video.

I guess as has been suggested I'm going to have to take it in and take a chance they can find it easily.

Maniac wrote: ↑Sat Sep 16, 2017 4:26 pm Nothing im aware of. It's only an issue when cold.

It's warmed up now and revs can be held at 1000 with ease.

When cold I get that bounce as per my video.

I guess as has been suggested I'm going to have to take it in and take a chance they can find it easily.

Any answer to my code reader question?

I borrowed a friends adaptor from work and it found nothing.