F10 M5 - Misfire when cold - injectors?

[magsmagsmags]

Hi all

Recently picked up an F10 M5 LCI. The car had no issues when I picked it up, drove home 4 odd hours without a hitch. Been sat on the drive for a week or so while as it needs a bit of tlc (new tyres etc etc)

Anyway when I first started it after being sat for a couple of days it misfired immediately and brought up a flashing CEL. If I plug into it, and clear the codes while it’s running the misfire goes and it runs absolutely fine - even if I do it within 10 seconds of starting. The codes shown are misfires cylinder 1 and 4.

I had read a few theories from injectors to the usual plugs and coils etc + a combination of flat battery and weak plugs and or coils.

I’ve since ordered a full set of plugs and coils anyway. But I’m debating doing injector 1+4 while I’m there.

As I can gather the Bosch one is the same as OEM minus BMW tax, but there’s EU5 and 6 types. Does anyone know which I need? And does anyone know the part number for the Bosch ones?

FWIW - if I start the car and clear the codes and restart it. It’s fine. If I leave the car to idle without doing anything those cylinders stay shutdown. Hence my thoughts on leaky injectors.

My only hesitation is that when my N54 had bad injectors, I had a really wobbly idle and rough drive for a good while until it was warm. This doesn’t do that. Idle is a little wobbly for 30s or so but it’s had a cold start delete and from what I can read this is quite common

Any advise and part number appropriated

Thanks all

[Denver_M5]

Did you put in new plugs yet?
Usually cold start missing can be caused by burned out plugs, I would start with plugs and you can see what condition they are in ones you have them out.
Also carbon build up on valves can cause a cold start misfire on direct injection engines, but I'm not sure if the S63 ever had a problem with build up on the valves.

[magsmagsmags]

Originally Posted by Denver_M5

Did you put in new plugs yet?
Usually cold start missing can be caused by burned out plugs, I would start with plugs and you can see what condition they are in ones you have them out.
Also carbon build up on valves can cause a cold start misfire on direct injection engines, but I'm not sure if the S63 ever had a problem with build up on the valves.

No not yet bud, they're on order.

I've got a few bits to do. New wheels/tyres, front discs and pads, rear pads, plugs and coils. So waiting for everything to arrive then borrowing a ramp an extra pair of hands next week to do the lot.

Will report back when I do plugs and coils. Just wondered if for the sake of £50-100 per injector, while i'm there if it's worth just doing them.

[magsmagsmags]

Update:

So among many other jobs this evening I tackled this with a mate.

Stupidly I misread the order of the cylinders. I was only replacing the two coil packs showing as misfiring (regretting this now)
Anyway. Changed what I thought was those and all the plugs (2 step colder gapped to 0.022)

The car was sat for about 4 hours before we pulled the plugs. All of them were dry, none were fouled and no fuel smell. So hopefully not leaky injectors.

On starting it after fitting them it seemed fine but got a misfire pulling out the garage.

Now one of the misfires is on a cylinder where I accidentally gapped a plug too small and had to try and prise it open. So worried I may have damaged the tip.

Anyway long story short. The error has now moved to 2 different cylinders.

I’ve now reordered 2 new plugs just because I can’t be arsed pulling it apart again (although it’s much easier than the internet tells me it is. One of the easiest cars we’ve done) and 6 more coils.

Will update again when done

[Denver_M5]

Nice, Hopefully it will take care of your misfire.
Why are you running a tighter gap on the plug?
Are you running more boost?

[magsmagsmags]

Originally Posted by Denver_M5

Nice, Hopefully it will take care of your misfire.
Why are you running a tighter gap on the plug?
Are you running more boost?

That's the recommended gap for tuned motors - according to these/other forums anyway. 0.022" for 2 step colder

Unfortunately it didn't solve my issue. Still shows misfires on 1 and 4

Still persists sadly. If it's been recently started, it's fine. If it's been sat it misfires until codes are cleared. It drives fine after this (exception of this below)

I tried putting my foot down a bit today however and it misfired on 4.

I suspect i need to tackle injectors.

Two questions at this point...

1. Is there any diagnostics I can do to pinpoint it at this point? I have INPA, ISTA and Bimmerlink that has live readouts and logging.

2. Does anyone know the correct part number for what injectors I need? The car is a 2014 LCI

Thank you

[Denver_M5]

Originally Posted by magsmagsmags

That's the recommended gap for tuned motors - according to these/other forums anyway. 0.022" for 2 step colder

Unfortunately it didn't solve my issue. Still shows misfires on 1 and 4

Still persists sadly. If it's been recently started, it's fine. If it's been sat it misfires until codes are cleared. It drives fine after this (exception of this below)

I tried putting my foot down a bit today however and it misfired on 4.

I suspect i need to tackle injectors.

Two questions at this point...

1. Is there any diagnostics I can do to pinpoint it at this point? I have INPA, ISTA and Bimmerlink that has live readouts and logging.

2. Does anyone know the correct part number for what injectors I need? The car is a 2014 LCI

Thank you

Monitor the HPFP pressure at the time you are getting the misfire also match it to your other bank HPFP pressure and see if there is any noticeable difference between the 2 pumps if that checks out it's probably the injectors that are failing.
I believe you will have to code the new injectors
I don't think you have a mechanical problem.
You installed new OEM plugs and coils right?

[magsmagsmags]

Originally Posted by Denver_M5

Monitor the HPFP pressure at the time you are getting the misfire also match it to your other bank HPFP pressure and see if there is any noticeable difference between the 2 pumps if that checks out it's probably the injectors that are failing.
I believe you will have to code the new injectors
I don't think you have a mechanical problem.
You installed new OEM plugs and coils right?

Good shout. Thanks. Will do that too. It would make sense I guess if bank 1 wasn’t getting enough fuel. My only hesitancy with suspecting injectors is everyone seems to note they get a fuel mixture error when an injector is failing.

I installed OEM Bosch coils yes. Not BMW branded but same part number.
Plugs were 97506 gapped to 0.022. I would say however once the misfire isn’t present it idles smoother than it did before.

Will do the monitoring and come back

Thanks for the help

[Solo_M_Tech]

Cold start misfires are caused by leaking injectors. It's not enough of an issue to cause constant misfires, but at cold start, they flood the cylinder enough to cause a misfire, once the dme's notice the misfire, it disables the injector for that cylinder until the codes are cleared. This has happened to my m5 twice. Once the engine was warmed up for a minute or so the misfire would go away with a key cycle and the engine would run fine all day. I diagnosed this issue by driving my car to work, then at lunch, removed the spark plugs on the bank I had misfires, bore scoped the cylinder and saw puddles of raw fuel on the piston crowns. Replaced all 4 injectors and spark plugs and haven't had an issue since. ( my injectors were replaced twice under the extended warranty for the injectors) for this exact issue.

[magsmagsmags]

Originally Posted by Solo_M_Tech

Cold start misfires are caused by leaking injectors. It's not enough of an issue to cause constant misfires, but at cold start, they flood the cylinder enough to cause a misfire, once the dme's notice the misfire, it disables the injector for that cylinder until the codes are cleared. This has happened to my m5 twice. Once the engine was warmed up for a minute or so the misfire would go away with a key cycle and the engine would run fine all day. I diagnosed this issue by driving my car to work, then at lunch, removed the spark plugs on the bank I had misfires, bore scoped the cylinder and saw puddles of raw fuel on the piston crowns. Replaced all 4 injectors and spark plugs and haven't had an issue since. ( my injectors were replaced twice under the extended warranty for the injectors) for this exact issue.

Unfortunately, i'm back...

Replaced all 8 injectors (plugs and coils already done) and - sadly, still the same. Misfires on 1 and 4 from the second the engine is started. And yes the flow rates are all coded before anyone asks

I am taking it in for a leak-down test this week so I guess that will either tell me my engines ####ed or if it comes back good - leave me even more confused.

I don't want to speculate too much at this point, but having spoken to a few knowledgeable engine tuners/builders and looking at other people's issues with low-compression due to a ringland or whatever else i'm really unconvinced it's a mechanical issue (maybe optimistic thinking...) The only associated symptom my car has is the misfire. There's no smoke from the exhaust at all. As I said before, once the fault's cleared it runs fine (granted - i did get a misfire when i put my foot down the other day on Cyl 4) but this doesn't fit the description for a broken ringland either. I can understand once the engine is warm it might expand and seal enough not to throw a fault. But i can have the scanner ready to go, start the car to an instant misfire, clear codes 1 second later and then it will idle and drive fine.

I haven't been driving it for obvious reasons, only to start and diagnose.

The only (possible!) plus is a new code has appeared today: 118110 - Mixture control 2, across banks: Mixture too lean. Looking on forums, answers a mixed, some say don't worry, some had issues to MAFs, some weak batteries, some were causing misfires. I'm reluctant to keep throwing parts at it without more diagnostics.

I did check the fuel pressures at idle today interestingly enough and it was only when writing this post i spotted the differences in the rail pressures

Fuel low pressure: 99~ PSI
Rail pressure: 775~ PSI
Rail pressure 2: 496~ PSI (oddly, the scanner we used show's all bank 1 ecu's/sensors etc. as 2, so this i assume is corresonding to bank 1

Annoyingly as I said, i didn't spot it at the time - just took some videos/pics of the live readings while in the garage. I'll hook it up to ISTA tomorrow and run through as many diagnostics as I can that seem relevant and re-check the pressures

Any further advice welcomed

[magsmagsmags]

Plugged in today again, fuel pressures fine. Can't see anything different across bank 1 / 2

[1320racer]

I've felt similar "misfire" frustrations. Stick with it and you'll figure this out.

(Shot #1)
On coils 1 and 4, verify the female ends of the wiring harness are totally clear of debris. Maybe spray them with alcohol or contact cleaner. While you are there, also inspect the 3 male pins on coils 1 and 4. Make certain they are not showing signs of damaged. If they are, maybe there is an issue inside the female connector.

(Shot #2)
How new is the fuel in your tank? I had an issue with my F10 M5 where it was very low on fuel and was not started for almost 3 months. I was chasing my tail trying to resolve the misfires just like you. I also installed the usual parts and I had no luck. I eventually poured in almost 7 gallons of new 93-octane fuel with a wacky funnel. I started the car and multiple misfires continued for several minutes as I was turning the car on/off and clearing codes many times. The errors eventually stopped once the new fuel made its way to the engine.

(Shot #3)
I had a freak instance where a moth go into one of the large DCM connectors while I was changing the spark plugs. This caused misfires as well as other random errors. After removing the moth's "body parts" with a dental pic and alcohol, the misfires went away. I am not sure if the moth caused electrical resistance issues or if the moth being inside the connector would not allow the pins to fully reach into the DCM.

GOOD LUCK!

[magsmagsmags]

Originally Posted by 1320racer

I've felt similar "misfire" frustrations. Stick with it and you'll figure this out.

(Shot #1)
On coils 1 and 4, verify the female ends of the wiring harness are totally clear of debris. Maybe spray them with alcohol or contact cleaner. While you are there, also inspect the 3 male pins on coils 1 and 4. Make certain they are not showing signs of damaged. If they are, maybe there is an issue inside the female connector.

(Shot #2)
How new is the fuel in your tank? I had an issue with my F10 M5 where it was very low on fuel and was not started for almost 3 months. I was chasing my tail trying to resolve the misfires just like you. I also installed the usual parts and I had no luck. I eventually poured in almost 7 gallons of new 93-octane fuel with a wacky funnel. I started the car and multiple misfires continued for several minutes as I was turning the car on/off and clearing codes many times. The errors eventually stopped once the new fuel made its way to the engine.

(Shot #3)
I had a freak instance where a moth go into one of the large DCM connectors while I was changing the spark plugs. This caused misfires as well as other random errors. After removing the moth's "body parts" with a dental pic and alcohol, the misfires went away. I am not sure if the moth caused electrical resistance issues or if the moth being inside the connector would not allow the pins to fully reach into the DCM.

GOOD LUCK!

Thanks for the detailed reply - and wow. My sympathy to you. Talk about annoying faults!

To answer…

1. I cleaned every contact on DMEs, injectors and coils today. What was very odd is thy after I did bank 1. I fired it up given that’s where my issues were and the misfire swapped to 7/8 (a first) where it would not clear. I repeated the same for bank 2 and they went back to bank 1. Whilst very odd. This is making me think / hope something else odd is up here and it’s not engine failure.

2. Fuel. So I filled it up with 99 on my way back. Had a quarter tank left when the misfires first started - so I don’t think that was my issue. The only way I can see it being this is if - just by coincidence I had a genuine failure on plugs or coils or injectors that caused it to start and have since put bad fuel in it. Ie. Massively unluckily. Otherwise it doesn’t add up. That being said. It’s in for a compression test tomorrow. If that checks out I’m slapping a new fuel filter on it and it’s getting brimmed with 99 and ran through.

3. Can safely confirm no months are in mine although I have once hit a pigeon at 120mph in a convertible. I’ll spare you the details but I’ll just say a lot went over me. The other half I pulled out of my engine - some of it quite well cooked

[magsmagsmags]

Okay so finally some good news

compression was fine. Very good in fact. 200 PSI across all cylinders. About 10 PSI variable but all above 200.

I drove the car round after until I had about 12 miles left in the tank then brimmed it with 99 (or 93 if you’re in the US). And on the way back - sent it. No misfires.

Now it only usually shows up when cold but I was getting a misfire appear under load a few days ago.

I’ve got a new fuel filter arriving tomorrow too

Will let it get cold and report back again

Thanks all for the help. Relieved the compression is good. Hoping it may be bad fuel or if not I just need to try and work out what on earth the issue is


UPDATE - Started it this morning, misfires on 1-4. Cleared codes. Drove fine.

Does anyone have any idea here? I'm at a total loss. It drives completely fine when cleared - there is something causing a misfire when the engine is first started. I'm beginning to think it might be fuel, or wiring related - but i'm at a complete loss.

[magsmagsmags]

Another update

After speaking to a BMW tech I know, they said they had a few of these in with ground issues on the loom that runs to the injectors and coils. Specifically the plastic 'block' they feed into, which is earthed to the head.

As it happens, mine was loose - wasn't ever bolted in to begin with and never thought anything of it - just thought i'll add bolts to my shopping list next time i'm passing the dealer and pop it back on.

So that's gone back on and the misfire on cylinder 4 has now disappeared

However i'm still stuck with cylinder 1. I did then completely dissassemble the whole loom, cleaned all the grounds up, cleaned everything with contact cleaner, but no dice.

I'm now convinced this is an electrical gremlin. Which would make sense as there is a huge current draw and electrical load when starting the car.

Any help more than welcome

[TinCanSailor]

Was it the ground wire near the DME's that wasn't secured? I ahd a few issues after I did my coils and plugs. I think I had to unplug and plug the DME harnesses and tighten the ground about 4 times before my M6 stopped giving me issues. My wifes 550 is in at our very trusted indy shop for a similar issue. They can find anything and are suspecting that fuel blend or ethanol might be at play. Not sure if you guys on that side of the pond switch blends at summer time but we have a summer and winter blend in the states sometimes the transition is problem free but we have noticed issues in the past that coincide with the blend change.

[magsmagsmags]

Originally Posted by TinCanSailor

Was it the ground wire near the DME's that wasn't secured? I ahd a few issues after I did my coils and plugs. I think I had to unplug and plug the DME harnesses and tighten the ground about 4 times before my M6 stopped giving me issues. My wifes 550 is in at our very trusted indy shop for a similar issue. They can find anything and are suspecting that fuel blend or ethanol might be at play. Not sure if you guys on that side of the pond switch blends at summer time but we have a summer and winter blend in the states sometimes the transition is problem free but we have noticed issues in the past that coincide with the blend change.

I know the one you mean but that wasn’t the issue no. It was the grounds on the head itself.

I’m just going to keep fiddling with the wiring and grounds there. If no dice a wiring diagrams coming out.

I’m in the UK so we don’t have that issue here. Pros and cons! Fuels consistent but no ethanol at the pump for us

[M5Rick]

When the dealership changed my plugs which had lost their hi power effect b/c of too many miles and getting a DTM on WOT they had to use fresh bolts to secure the hardware around the coils etc. I started using Esso Supreme also instead of Tesco M99 as I'm a bit afraid that it's more likely supermarket bad gas may be more commonplace than the real thing.

[magsmagsmags]

Originally Posted by M5Rick

When the dealership changed my plugs which had lost their hi power effect b/c of too many miles and getting a DTM on WOT they had to use fresh bolts to secure the hardware around the coils etc. I started using Esso Supreme also instead of Tesco M99 as I'm a bit afraid that it's more likely supermarket bad gas may be more commonplace than the real thing.

Yeah its a common fault so much as I can see. I assume being a dealership they would just replace the bolts and connections for new because... well they're a dealer. They're not going to sit there with sandpaper and clean them up when they can charge you for them but serves the same purpose I guess.

Oddly enough, i had esso supreme in it before - wondered if that was the cuplrit, so went back to momentum. I had my old car custom mapped on momentum and never had an issue. I'm not convinced by the supermarket fuel argument - at least for premium fuels.

[M5Rick]

Originally Posted by magsmagsmags

Yeah its a common fault so much as I can see. I assume being a dealership they would just replace the bolts and connections for new because... well they're a dealer. They're not going to sit there with sandpaper and clean them up when they can charge you for them but serves the same purpose I guess.

Oddly enough, i had esso supreme in it before - wondered if that was the cuplrit, so went back to momentum. I had my old car custom mapped on momentum and never had an issue. I'm not convinced by the supermarket fuel argument - at least for premium fuels.

I had already been quoted a fixed price for the plug change so the extra 50 quid for the extra bolts and what not was waived, plus you get the two years parts and workmanship guarantee with the welcome peace of mind. I think I'll vary fuels and use M99 sometimes,I'd love to use Costco fuel which is Mobil derived but the nearest Costco gas station is 40 miles away from me!

[M5Rick]

A correction in that Costco Australia has Mobil sourced petrol because of their regulations. In UK Kirkland fuel for Costco is bought from various refineries.

[magsmagsmags]

Still chasing this if anyones got any other bright ideas. I’m 100% convinced the issue is electrical at this point. But not sure what or where