[Mus22]

Another update. BMW responded to me question this is so unusual.

Just an update from BMW Customer service ;

Hello Mus

Thanks for your email about your BMW fuel rail pressure.

I’ve spoken to a BMW Centre and been told that the fuel rail pressure upon ignition should be 5 bar.

I hope this resolves your query and if there’s anything else I can help you with plea do not hesitate to get back in touch with me.

Kind regards



BMW Group
United Kingdom

[ShoCk_]

Did you buy the car knowing it was misfiring or were you sold the car in working order but it developed the misfire ?

Sounds like a money pit if you don't know what you are doing. Garages have an easy opportunity to charge you labor/parts for all sorts trying to get to the bottom of it.

[Mus22]

hi buddy as mentioned above car was bought with misfire and the cause of the misfire was identified by me. im not a bmw specialist but have built enough bmw engines to know what im doing.

this is a separate issue to the miss fire.

[Andy198712]

Hmmmm? So your fuel pressure is okay then?
(Although mine is 35bar too many?)

[Mus22]

im confused just as much as you buddy.

[Andy198712]

i'll double check my results sunday when the car has sat over night, the 40 could have been from recently being used an hr before....mine is the N57 3.0 single turbo though too....

[Mus22]

yeah let me know Andy really appreciate your help

[Andy198712]

Will do

[Mus22]

lpfp purchased will be installing tonight will update tonight

[Mus22]

so guys no luck im pushing for injection pump now and if thats not it im breaking the car

[Mus22]

i give up hpfp changed lpfp changed all sensors relating to fuel changed. There is nothing else to change it started for 3 seconds and stopped.

[Andy198712]

And no codes?
What a nightmare!
Guess that leaves ecu or something stupid like fuel filter?
It ran on easy start right?

[Mus22]

Hey Andy

ye its been a bit sh*t to be honest. I have given it a break for a couple of days. The Guru Uncle is back from holiday so he reckons injectors or one I stuck open so lets see ECU is fine apparently checked by a mate of mine. so Injectors that's what it seems to fall down too. I have done further research and have been told on the m57n2 engine even one injector can not start the car if its faulty. I'm going to do a leak off test tonight and see how that goes.

[Andy198712]

Fingers crossed! Time away deffo helps with these things! For your sanity mostly!!

[old grey steve]

Just read this quickly very interesting indeed. A real long shot and I'll be quick, but two things strike me as slightly unusual (though not unheard of) which are

1/ After I did a compression test I found that cylinder 1 had no compression so I started dismantling the engine.

2/ Took of the rocker cover to find the Rockers above cylinder 1 valves were broke and others cracked so I replaced all 24 rockers

Seen from memory 3 M57's where the chains let go or the chains gone slack with compromised rockers so a mechanical issue for these engines if it takes place for me isn't unheard of. Dont forget if the inlets lost a swirl flap as well you'll lose compression on a cylinder potentially as well, but this won't necessarily stop an engine from starting as I've seen many a swirl flap infected M57 start with more than 1 cylinder corrupted by swirl flap ingestion.

Though not directly similar to the faults above I've seen 2 M57N2's which had no recorded faults, wouldn't start and as a last resort ended up with us, when we've thought outside the box after carrying out the usual diagnostic to ensure everything had been covered we actually opted to pull the crank sensor check this and check the flywheel itself only to find debris on the sensor and damage on the flywheel (bent tooth on one missing tooth on another) both of these engines had no faults garages had in the past replaced various fuel components but had got no where and it is frustrating.

I might be barking up the wrong tree but if the engines had a mechanical issue my first though is a mechanical problem may still exist.

Might be worth a look even if its to rule this out.

[Mus22]

Hey Steve

Thanks for your input engine not starting is a fuelling issue as the rail pressure start building up to specific rail pressure and start for say 2 seconds or tries to start and stops. Now yesterday it started for 15 seconds I was dancing then it cut out again. The only reason I changed the rockers is due to the misfire when I first bought it. The misfire is fixed but this crank no start seems to be a new problem as the engine was starting and driving when it had the misfire. the 15 seconds it was running engine was running perfect no knocks no bangs all in time.

I did a leak off yesterday but not a drop of fuel came out in the bottles which is odd.

[Mus22]

Right guys even though im abit embarrassed of the issue car starts and drives. i started unplugging the injector cables one by one and cranking. took of 5 and car worked put in the spare injector i had car is now up and running. i seem to have another one leaking on top of the engine but not causing issue. will sort that too.

i do have one other issue though each time car is idle oil pressure light comes up. now i know this is common on the n43 2 petrols with the oil control valves.

i guess next step is sump off and check if anything is stuck in oil strainer.

[old grey steve]

Originally Posted by Mus22

Right guys even though im abit embarrassed of the issue car starts and drives. i started unplugging the injector cables one by one and cranking. took of 5 and car worked put in the spare injector i had car is now up and running. i seem to have another one leaking on top of the engine but not causing issue. will sort that too.

i do have one other issue though each time car is idle oil pressure light comes up. now i know this is common on the n43 2 petrols with the oil control valves.

i guess next step is sump off and check if anything is stuck in oil strainer.

Good that you've discovered something injector loom wise re oil pressure issue they was my previous post directed thought something mechanical may just may have happened, revtheir N43/46 engine we see stacks of them usually fault wise you'll have a possible oil pressure static fault and yes sump off not unusual on the N43's and alike to see timing chain debris blocking the strainer and sitting in the sump plus on the hydraulic valve on the side of the block seen these come apart when removed or have contamination issues when extracted on N43's but on the diesels not so common. Trouble as you may know with the M57 for instance is unlike the petrol variant opting to say change a chain tensioner isn't quite as straightforward but at the same time it seems more robust but thsts not to say they haven't had issues hence the odd one I've seen that's gone AWOL.

[Mus22]

Don't quote me on this but I saw the chain and guides briefly on this and the guides look new and feel new. I have a feeling half of a rocker has fallen in to the sump. From what iv seen whoever touched this car prior to me doesn't know how to put a sump back on as I have red gasket seal everywhere under the car.

[old grey steve]

Originally Posted by Mus22

Don't quote me on this but I saw the chain and guides briefly on this and the guides look new and feel new. I have a feeling half of a rocker has fallen in to the sump. From what iv seen whoever touched this car prior to me doesn't know how to put a sump back on as I have red gasket seal everywhere under the car.

So its had a potential mechanical event before? Which was what I first read into things when you were replacing rockers as its unusual to go down this route unless something has happened thing is is something has happened and someone has been in here before then for the sake of time you have to rewind the tape and do what you have to do and go in to the sump I guess now you know something isn't right but at the same time as I said on my first post one of the engine with flywheel damage had had engine issues as well. So though you look to discount it its worth a look at least IMO.

But if guides look newish then you have to ask if they have been replaced where's the debris gone. 99.9% of the time gravity takes care of this and they end up on the sump and from there cross contamination takes place

[Andy198712]

Glad the starting is sorted!
Could have excess sealant blocking the pickup maybe then?

[Mus22]

Thanks Andy Possibly but didn't do it on the way to work today which is strange. I also have one of the injectors pissing out a little as the rocker cover gets flooded abit. Engine is running so that the main thing I will sort the rest out. I guess a leak off will be better now and I can work out which injectors properly need changing.

But here is something to keep in mind by pulling out each injector cable/harness one by one and cranking to see if it will start does work I was told it wouldn't.