e65 745i misfire/lumpy idle when starting from cold

[Patrick Bateman]

Noticed the idle when first starting the car from cold can be a bit lumpy for a bit and when engaging reverse to get off the driveway there's quite a lot of vibration, very odd. When starting the car leaving work tonight the EML flashed and I got a warning to drive moderately due to an engine fault.

This message and the EML disappeared again almost as quickly as it had appeared and the car drove completely normal. This only seems to happen when starting the car from cold although even when the idle is steady and the car is up to temperature I'd say I still feel more vibration than I'd expect in such a car.

Whipped out the laptop with DIS and INPA and got the following-









There are also secondary air system faults for banks 1 and 2 although not sure if they'd be connected to this?

[Prinny]

Sounds very like my current issue. BM think it’s the coilpack on mine. You at least have a cylinder number to go at, I just had “bank 2”.

It’s the intermittent nature of it that gets me, I can start the car and drive 2 miles before it rears it’s head, but then sometimes, catching it ‘right’ and revving, it’ll go away & not come back at all that journey.

Bloody infuriating.

Mine’s now in the dealer getting 12x plugs (in theory due now anyway) and so while there, they’re going to find the pack in question (should be obvious from plug) and hopefully fix it for good.

Do you need to take the inlet manifolds off on the 745 to get at the coil-packs? If not, obvious 1st port of call to me...

Secondary air codes could be rubber fatigue somewhere in the breather / vacuum pipes?, easy enough to take them off 1 by 1 and rule it out as an option I suppose!

[eliot]

Does it sound like it’s blowing? Mine was leaking where the mid exhaust connects to the cat - the 6mm nuts had rusted away and it was leaking at the joint.
I was getting idle problems and some codes - which went away once i replaced the nuts and stopped the leak.

[helix402]

Swop coils for cyl 7 and 8 to other cylinders. See if the faults follow. Also you can activate the engine cooling fan via DIS to check if it works. Air faults are a lesser concern than the misfires.

[4340BB]

I would be confident to say coil pack. Just had exactly the same symptoms as you stated.
Instead of replacing one I just replaced the lot as my mechanic friend said that when one goes they will all tend to follow suit. If you catch my drift.
Did them all myself as its an easy job on a straight six. Wouldn't know so much about a V8 but I bet they are just as easy.

[Patrick Bateman]

Thanks for the suggestions, swapping the coil packs sounds like a sensible approach, just hope access to cylinder 8 isn't terrible.

Regarding the fan, e65Ross mentioned he had the same fault when he owned it and it's nothing too important unless you're in a hot environment in traffic. I'll give it a look at some point though.

[eliot]

It’s not too bad - you do need an e-torx e6 socket though from memory.
Pictures from that area when i did the valve stem seals:
http://www.mez.co.uk/page129.html

[Patrick Bateman]

Bloody torx sockets, the one thing my halfords socket set doesn't have.

[Prinny]

Feedback from the garage on mine. (woohoo, only been there 40days...)

Not coilpack, but plugs. One plug is distinctly ‘buggered’. I haven’t seen it yet (Monday), but they’re confident it’s now good.

New manifold gaskets too, (that’s the v12 design), more when I have it...

[Patrick Bateman]

Access looks a bit tight-



Might just give cylinder 7 a go and if the fault moves then worry about 8. Not sure if cold weather makes this worse as it was -6 this morning and the eml didn't disappear, I had to switch off and restart the car. It had been fine all weekend.

[Prinny]

Well if it makes you feel any better, I’m still in the same boat. Got to the garage around 10, and picked up the keys. Open the door & fire up.

EML light is on and idle is lumpy (obviously misfiring). Turn off, back into dealership...

I’m now not sure they’ve even done any analysis, just hoped for the best on the plug change (or did they even do one?) The car is displaying the exact same fault it went in with, in November.

Suffice it to say, there’d better be a good explanation forthcoming, and PDQ.

[Patrick Bateman]

Bit of a palava tonight. Oil pressure warning came on but has since disappeared, got the car back to the house on a flat bed to be on the safe side though.

Now that it's dry I've noticed the car has been dripping oil all over the drive and there's a recorded misfire on cylinder 3 now as well as 7 and 8.

In the space of an hour since getting home there's a decent number of drops on some cardboard I've put down-




I can see the undertray is damp with oil but it's difficult to see the oil pressure switch without some disassembly. Hopefully that's the source of the leak then it'd also explain the warning that appeared.

Edited by Patrick Bateman on Monday 8th January 20:22

[Patrick Bateman]

Bit of an update, just got this from the car-



Am I safe in saying that since the misfire is now affecting 5 cylinders that's it's highly optimistic to think this is just something to do with the ignition coils? Reading about these symptoms online suggests the valvetronic intermediate levers as being the potential issue.

If the car is misfiring badly and the EML stays on, simply stopping and restarting the car instantly makes it disappear.

[Elliot2000]

Sounds like an air leak on the breather system to me- the misfires on so many different cylinders indicates it isn’t likely to be coil, spark or injectors. An air leak would lower the air mass readings and cause the car to back off fueling starting to cause misfires.

Take off the engine covers and on both rocker covers you will see two round plastic discs with a little spout thing- unclip them and look at the rubber diaphragms and check for splits

[Patrick Bateman]

Thanks for the suggestion.

It's got its MOT in 2 weeks so will get it looked at then.

Would the misfire disappearing after stopping and restarting the car be consistent with a breather issue?

Am I right in assuming you're referring to item 13 here-

http://www.realoem.com/bmw/enUS/showparts?id=GL62-...

Edited by Patrick Bateman on Saturday 3rd February 21:08

[Elliot2000]

Not a breather issue as such- but a split diaphragm on the breather which intorduces an air leak into the intake system as the breathers feed crankcase fumes but into the intake to get burnt off . They used to be orange diaphragms which split really easily but then changed to blue ones that lasted longer but still split eventually.

[Patrick Bateman]

This sounds so easy I'll hopefully just look myself tomorrow.

Only thing is I'd have thought this issue would cause a misfire all the time, regardless of stopping and restarting the engine.

That being said, even with no misfire the idle is generally fairly lumpy and not what I'd expect- nothing like how the V8 in my M5 idled. I can feel the lumpiness in the cabin myself.

Here's a video of the rev counter at idle-

https://www.youtube.com/watch?v=TRaYRxSdF-E

After a few minutes this was how it was idling-

https://www.youtube.com/watch?v=fM9_Vc6Gu78

Edited by Patrick Bateman on Saturday 3rd February 22:24

[Patrick Bateman]

Both diaphragms look good, I suspect they were replaced when the rocker cover gaskets were changed. Can't see any obvious split in the pipework.

All I can see is this-














The second one is the tubing coming from the MAF sensor. The rest are electrical.

Could that split being after the MAF sensor cause this? Or a frayed cable?

Edited by Patrick Bateman on Sunday 4th February 13:57

[Elliot2000]

Did you take the diaphragms out and check?

The first one is indeed for wiring, the second one doesn’t look big enough to cause an air leak as it will still be sitting on the profile of the intake manifold sleeve from the length of it that I can see

If you have dis and inpa, can you actviate the secondary air pump and see if it sounds overly noisy or if you can hear air escaping from the pump or pipework

[Patrick Bateman]

Physically took them out, looked new.

I have thought the pump that runs when the car starts was a bit noisy but was never sure if that was typical. There are fault codes in the image up the page relating to secondary air mass and the pump.

How to I go about activating it in INPA?