[Bubbaspaarx]

Hi all,

Long story short, I got a HPFP replaced after it dismantled itself and I don't think the company who carried out the repair did it properly. I've exhausted my patience asking them to fix it so I'm doing this next part myself.

Car is still driving fine and have actually covered nearly 5k since it was done. The issue is that the system loses pressure so turning the car on can take a second or two before it fires (which leaves errors) and booting the car at peak torque will throw drivetrain errors or turn the engine off entirely. Between those two things though, it's never driven better.

Assumption is that the one or more of the injectors have crap in them from the dodgy repair and they are unable to fully close hence the loss of pressure. Can't be certain though.
A local engineer told me to take the return pipes off the top of the injectors and see if any fuel comes out during turn over.. apparently there shouldn't be any at this time. Tried last night and am not sure if they are or aren't. Turn over doesn't last long enough to say for certain. I'll upload vids though and just want to know if anyone spots anything particular.
TIA

[Eddamoo]

If you want to check the return pipes on crank I would pull the coils or better yet, pull the plugs to allow the cylinders to dry. That will give you your longer crank time to check.

If you have a leaking injector that should be pretty obvious by smell. The cylinder should be cleaner (borescope) and you should be able to smell the fuel. Unplug the coils and injector leads and allow the car to crank for 30 seconds to allow the Hpfp to feed them, then inspect the cylinders one by one to give your nose a chance of detecting it.

I'm not certain it would be as it also happens on WOT. That suggests there could be a restriction somewhere.

Are you using ISTA? If not I'd recommend trying some of its procedures. Can you publish the exact ISTA codes?

[Bubbaspaarx]

Originally Posted by Eddamoo

If you want to check the return pipes on crank I would pull the coils or better yet, pull the plugs to allow the cylinders to dry. That will give you your longer crank time to check.

If you have a leaking injector that should be pretty obvious by smell. The cylinder should be cleaner (borescope) and you should be able to smell the fuel. Unplug the coils and injector leads and allow the car to crank for 30 seconds to allow the Hpfp to feed them, then inspect the cylinders one by one to give your nose a chance of detecting it.

I'm not certain it would be as it also happens on WOT. That suggests there could be a restriction somewhere.

Are you using ISTA? If not I'd recommend trying some of its procedures. Can you publish the exact ISTA codes?

Thank you for this.

I've never pulled the coils before and don't have an enormous set of tools. Is it easy enough to do?

The codes I'm getting are (edit- these are from Bimmerlink but think they share the same codes)

247500
247600
248600

All rail pressure errors.

I take it the videos were unhelpful too..

[Bubbaspaarx]

Also, with WOT I've tracked the psi and it's lower than it should be. Absolutely fine in the mid ranges. Makes me think that whatever it is, it's really small.

[Eddamoo]

Apologies i thought for some reason this was a petrol! I didnt see the video as i didnt want to risk waking a sleeping baby!

Please ignore the Plugs/Coils comment! Its also much more of a faff to remove the injectors as it usually requires new copper washers, o-rings etc.

It does sound like one or more of the cylinders is struggling to fire, but im not certain a leaking injector would cause a low fuel pressure code at WOT. Injectors will be at very high duty cycle so the leak will be far less evident.

I believe there is a gauze filter on the HPFP, i would be looking there for any swarf. I suspect the sensors should be ok.

It may be worth posting in the N47/57 section as theres likely far more knowledge in there

[Bubbaspaarx]

Originally Posted by Eddamoo

Apologies i thought for some reason this was a petrol! I didnt see the video as i didnt want to risk waking a sleeping baby!

Please ignore the Plugs/Coils comment! Its also much more of a faff to remove the injectors as it usually requires new copper washers, o-rings etc.

It does sound like one or more of the cylinders is struggling to fire, but im not certain a leaking injector would cause a low fuel pressure code at WOT. Injectors will be at very high duty cycle so the leak will be far less evident.

I believe there is a gauze filter on the HPFP, i would be looking there for any swarf. I suspect the sensors should be ok.

It may be worth posting in the N47/57 section as theres likely far more knowledge in there

Much appreciated. My bad too. Should have said it was a 330d… would have helped lol.
Will post there now 👍

[sean5302]

I had just this problem and fixed it by doing a leak off test and replacing one injector that was stuck open.
The common rail pressure should be 200bar after a single engine rotation (yes, 3000 psi).
That rises to 2000 bar at high engine speeds.
If you turn the engine off, pressure should remain in the common rail for approx 20 seconds. It won't if any of your injectors is stuck open.
Have a look at your exhaust with the engine running. Do you see white smoke? Can you smell diesel? Sure signs of a stuck injector.
Other possibilities (much less likely) are a faulty pressure sensor on the rail, a fuel starvation from either tank lift pump or high pressure pump.
Have you got a code scanner? If you're around Yorkshire I may be able to help you.