Common rail injectors

[n0v0s]

Injectors are from a bmw 330d with the newer 3.0 m57n engine (don't shoot me, its still a derv )... Two injectors are suspected as having excess leak off causing the rail pressure to drop. I'm yet to double check but it is also possible some diesels getting into the sump which fits..

The car doesn't fire up, unless easy start is used which makes sense as it cranks the engine over faster than the starter, raising the pressure over the high (think its ~500bar) threshold required. Have to give it accelerator or it stalls. On warming up, obviously leak off will greater so it appears to miss a slight amount. I'm still waiting for my fancy bmw diagnostics to turn up so that i can check all this shit out but after having eliminated the in line pump and two pick up pumps in the tank.. the injectors are most suspect.. No actual fault codes to record, no eml on either so doubtful its the cam/crank sensors or rail pressure sensor? Can only truly rule them out after my reader turns up (inpa/ediabas if anyones interested!)

SOOO, my question

What is most likely to cause the excessive leakage on crd injectors? Is it simply wear internally in the nozzle? Or could it be a simple seal and dirt issue? Most likely option is to refurb all 6 with new bosch nozzles ... BUT, if its not much more expensive i am planning on fitting 535d nozzles - think they amount to under £500 a set if using my own injector bodies.. If its as simple as opening up my injectors now and shoving the nozzles/body into an ultrasonic bath then i'd give it a shot! Milleage is under 100k!

anyways.. enough of the essay. cheers

[Ruan]

Sounds like the nozzles are absolutely f*cked... Though the diesel in the sump is a worry, unless you had a severely dribble injector you'd struggle to get that...

My biggest worry would be getting the injectors out the head, they're renound to be a complete Bastard on the m57s..

Have you got a map ready for the 535d nozzles, since it'll just smoke continually otherwise, since the ecu has no idea that its got some chronic nozzles in...

[Poodle]

I understand it's knackered solenoid needles in the injector body that cause excessive leak-off, not the nozzles. Are you saying that there is actually diesel in the sump now, or that you think there might be? Don't quite understand that sentence... Have you done a leak-off test on them, or is that another assumption?

[n0v0s]

Sounds like the nozzles are absolutely f*cked... Though the diesel in the sump is a worry, unless you had a severely dribble injector you'd struggle to get that...

My biggest worry would be getting the injectors out the head, they're renound to be a complete Bastard on the m57s..

Have you got a map ready for the 535d nozzles, since it'll just smoke continually otherwise, since the ecu has no idea that its got some chronic nozzles in...

The engine was warm/hot so oil had obviously thinned down, there was no smell of diesel in the oil though. However, i shall go check now with a cold engine. I doubt there is diesel getting in, more of a worse case scenario - which would more likely lead to a leaky high pressure pump, dripping derv into the sump. Engines nice and quiet though, however it must be chronically overfuelling as it is smoking when revd hard - ecu probably over compensating. The throttle is extremely sensitive too, slight prod and it revs up quuuick!

Getting the injectors off the head could be a nightmare, will probably have to buy a puller. Make life easier. I don't have a map ready, need to find somebody willing to email me a map with adjustments and power to my spec. The popular e-maps dude will only map to his 260bhp xxxlbft usual spec. Any recommendations?

If i was to have the car properly mapped to accept the 535d injectors, would fuel economy be noticeably worse than it would be on original 330d injectors + map? I'm thinking that it should be the same, assuming driving similiarly due to the injection duration/quantities being balanced out by ecu to meet requirements..

i.e. although 535d injectors nozzles flow more per injection... But they could have their inj duration reduced and timing advanced in which to inject the fuel compared to 330d injectors .. ultimately putting in the same mm3 of fuel per stroke at X demand hence resulting in possible greater efficiency/ increased mpg over 330d if driving like miss daisey? If found someone to rebuild my injectors, just need to ascertain if 535d injectors will kill my economy or not over original injectors if driving with mpg in mind when mapped. Costs are quite similiar to refurb!

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I understand it's knackered solenoid needles in the injector body that cause excessive leak-off, not the nozzles. Are you saying that there is actually diesel in the sump now, or that you think there might be? Don't quite understand that sentence... Have you done a leak-off test on them, or is that another assumption?

Ahh i see, so would that require a complete new injector body or is that solenoid needle assembly able to be replaced/refurbed? Why do they cause excessive leak off? Wear? or is it because they get jammed? Basically, what does it amount too... a simple diy opening of injectors and freeing/cleaning the solenoid? OR new complete injectors/or solenoid assembly? As above, will go check the oil now whilst it is cold. Leak off test to be performed shortly, but if i can't find the correct pipes, i might just do a quick injection on only leak off, see if they can hold. Any which dribble are most definitely fked! Not definitive, but quick and easy!

I'm yet to fully learn about crd injector operation, big step up from idi dervs! Cheers for both of your input lads! Great knowledge. If i can just find a SMF and clutch assembly to suite i would like to go quiet stupidly north of 300bhp and 600lbft. Don't mind poping a few 2260vs, suppose i could get used to welding the rear subframe too lol

[Poodle]

Couldn't tell you myself, i just know it stops after a refurb lol. As i understand it, it's down to wear so new parts are required, whether that's the solenoid needle itself or something else i'm not sure.

Injectors are meant to leak off x amount, it helps with cooling apparently. Cully's done a guide for the test somewhere, should be done over at least 20 minutes really.

[cully]

may not be here but here

this is a verygood video to watch very informative

[n0v0s]

Thanks for that Cully, i've seen your post on pug306 before. I checked leak-offs with the pipes disconnected and just the ignition on - apparently there should be no leak off at all if the injectors are good. Can anyone confirm this?

I appear to have all 6 injectors slowly dribbling fuel out with full ignition on and the pre supply pump on/primed. However, the adaption values of all 6 injectors are within tolerance when checked with inpa??!

Also, the rail pressure should build up to and hit 390bar (up from 8.75bar with just the pre pump primed) on cranking in order to fire up. Mines hitting just 30bar! If i pull off the rail pressure sensor, the rail pressure is set to a default nominal value of 390bar instead of 8.75bar - but still doesnt start.

[Ruan]

Sounds like HP pump AND injectors to me...

When driving what's the RailPressure like?

Has it been wrong fueled? Sounds like it has to me - someones put 30l of petrol in and ran it hoping it'll be OK...

[n0v0s]

I was just about to check the rail pressure with the engine on, but the fkin battery ran out of juice. Would have ruled out the high pressure pump. Will check it tomorrow. Btw, i don't think diesel is getting into the sump - oil doesn't smell of it.

Not a clue about whether its been miss fuelled or not. Apparently cut out whilst driving on the motorway. Assuming it has been, then it would make sense that all 6 injectors are leaking (btw, is it correct that they shouldn't be leaking with just the ignition on?)

However, surely if it had been missfueled and the HP pump shagged, then it would refuse to start at all. If the HP can only generate 30bar at ~2/300 rpm cranking, then it wouldn't generate the ~300bar+ to keep the engine runing (with the help of easystart) and wouldn't rev up at all - its very responsive and eager to rev!

Symptom summary; Once started, as said, the throttle has to be pushed to keep it idleing, otherwise it cuts out. When warmed up, there is a noticeable miss but it isn't drastic or anything - possibly caused by thinner fuel making leak off rate greater... There is smoke if rev'd hard. The throttle is overly sensitive to the slightest prod maybe due to injectors overcompensating - yet injector mass adjustment values are fine

[Ruan]

Pull the FRPS and FPR and clean them... See if that helps...

If the regulator is jammed or if the pressure sensor is reading shagged values, the ECU will just be having a shit fit of information... It's common for sensors to read wrongly, but not out of range, the ECU assumes it's correct since it's not out of range, but it hardly runs...

[n0v0s]

The rail pressure is fine once the engine has actually started, it meets the expected rail pressure when reved up according to live diagnostics. So HP pump must be ok, and even though the rail pressure hits.. say.. 600bar, the pump may be producing a shitload more to get the rail pressure to 600, due to having to overcompensate for the excess leakage.

It's only when near idle rpm where it struggles to reach the expected 300bar - the actual rail pressure shows as 200bar if i keep it near 800rpm with accelerator - as soon as foot is removed, it drops below 200 and obviously cuts out.

Soo.. i've took the injectors out and having a friend of a friend at carwoods check them out for me. Should really have done a leak off test but, well.. i;m just going to take a risk! Shouldn't cost too much to have them properly tested!

[Poodle]

FPR jammed brings up a specific fault code on the 306s, so i would expect it to on one of these too. If the injectors are leaking off more than they should that could drop rail pressure just as significantly as if the HP or LP pumps were dodgy. Cleaning that and the rail sensor sounds like a good shout to me, two common culprits.