35i 'surging' under power with no error codes!

[R.E92]

Can you tell me what the expected fuel rail pressure parameters are please?

It depends heavily on the conditions. Fuel pressure should be up around 2000 PSI at full chat and 700 at normal cruising.

During a cold start the fuel pressure should jump up to 2500-3000 then settle around 2500 after until the cold start has finished.

A warm start I think would stick around 700.

Here's what my cold start fuel pressure looks like:
https://datazap.me/u/rich/cold-start-vanos?log=0&data=19-20

Here is a log of some normal driving with some occasional acceleration:
https://datazap.me/u/rich/335i-v53?log=0&data=4-22-23

Thank you for the info, your second link does not appear to work but the rail - RPM chart is very useful

Second one should work now. I had it set to private

 

[mcbutler]

It depends heavily on the conditions. Fuel pressure should be up around 2000 PSI at full chat and 700 at normal cruising.

During a cold start the fuel pressure should jump up to 2500-3000 then settle around 2500 after until the cold start has finished.

A warm start I think would stick around 700.

Here's what my cold start fuel pressure looks like:
https://datazap.me/u/rich/cold-start-vanos?log=0&data=19-20

Here is a log of some normal driving with some occasional acceleration:
https://datazap.me/u/rich/335i-v53?log=0&data=4-22-23

Thank you for the info, your second link does not appear to work but the rail - RPM chart is very useful

Second one should work now. I had it set to private

Excellent thank you wondering if carly can read fuel rail live data, will have a look tomorrow

 

[mcbutler]

OK - small but probably importnant new detail. After meeting up with phoenixboy (Grant) yesterday I notoced quite a strong smell of fuel after anohter weak hearted warm start.
I am erring towards injectors leaking - been told Indez 12 are arounf £450 each - warranty direct will love this lol
No codes though - surprisingly

Thoughts anyone

 

[R.E92]

You can pull your spark plugs and see if they are wet with fuel.

You can also use a borescope and feed it into the spark plug hole and see if the injector leaks fuel while the fuel pump is primed.

New injectors are about £250 each. Fitting would be 2hrs labour.

 

[mcbutler]

You can pull your spark plugs and see if they are wet with fuel.

You can also use a borescope and feed it into the spark plug hole and see if the injector leaks fuel while the fuel pump is primed.

New injectors are about £250 each. Fitting would be 2hrs labour.

Thanks for the idea, I have seen the index 12 injectors, mine are index 6! Considering changing them regardless to be honest.

How long after engine off would you wait to look at the plugs?

 

[enuff_zed]

How long after engine off would you wait to look at the plugs?

I'd think well after it's all gone cold, as the heat will evaporate any fuel on them to begin with.

 

[R.E92]

You can pull your spark plugs and see if they are wet with fuel.

You can also use a borescope and feed it into the spark plug hole and see if the injector leaks fuel while the fuel pump is primed.

New injectors are about £250 each. Fitting would be 2hrs labour.

Thanks for the idea, I have seen the index 12 injectors, mine are index 6! Considering changing them regardless to be honest.

How long after engine off would you wait to look at the plugs?

As quick as possible. The injectors leak while the rail is pressurised so if you wait too long the rail pressure will drop and they will stop leaking. You can search YouTube for videos showing it happen on all kinds of cars.

I had index 6 injectors on my 3 series. I changed them as a precaution as i noticed the oil had a fuelly smell during an oil change. The car ran fine but leaky injectors can be disastrous for engine wear as they can dilute the oil.

If you're keeping the car for the forseeable future it would be worth changing them regardless. You could keep an eye out for a used set on eBay, index 12s usually fetch £125 each used. You can get a full set of new ones for £1200 from deutsch parts on eBay.

 

[enuff_zed]

As quick as possible. The injectors leak while the rail is pressurised so if you wait too long the rail pressure will drop and they will stop leaking.

That's me told then.
I'll get back to my old carbs. :roll:

 

[mcbutler]

You can pull your spark plugs and see if they are wet with fuel.

You can also use a borescope and feed it into the spark plug hole and see if the injector leaks fuel while the fuel pump is primed.

New injectors are about £250 each. Fitting would be 2hrs labour.

Thanks for the idea, I have seen the index 12 injectors, mine are index 6! Considering changing them regardless to be honest.

How long after engine off would you wait to look at the plugs?

As quick as possible. The injectors leak while the rail is pressurised so if you wait too long the rail pressure will drop and they will stop leaking. You can search YouTube for videos showing it happen on all kinds of cars.

I had index 6 injectors on my 3 series. I changed them as a precaution as i noticed the oil had a fuelly smell during an oil change. The car ran fine but leaky injectors can be disastrous for engine wear as they can dilute the oil.

If you're keeping the car for the forseeable future it would be worth changing them regardless. You could keep an eye out for a used set on eBay, index 12s usually fetch £125 each used. You can get a full set of new ones for £1200 from deutsch parts on eBay.

Job for tomorrow then.

I have done a seller search on the Bay for deutsch parts, nothing found!!!

 

[R.E92]

Thanks for the idea, I have seen the index 12 injectors, mine are index 6! Considering changing them regardless to be honest.

How long after engine off would you wait to look at the plugs?

As quick as possible. The injectors leak while the rail is pressurised so if you wait too long the rail pressure will drop and they will stop leaking. You can search YouTube for videos showing it happen on all kinds of cars.

I had index 6 injectors on my 3 series. I changed them as a precaution as i noticed the oil had a fuelly smell during an oil change. The car ran fine but leaky injectors can be disastrous for engine wear as they can dilute the oil.

If you're keeping the car for the forseeable future it would be worth changing them regardless. You could keep an eye out for a used set on eBay, index 12s usually fetch £125 each used. You can get a full set of new ones for £1200 from deutsch parts on eBay.

Job for tomorrow then.

I have done a seller search on the Bay for deutsch parts, nothing found!!!

https://www.ebay.co.uk/itm/BMW-Fuel-Injector-Index-12-N54-N63-135-335-535-550-750-X5-X6-M-13538616079-SET-6-/153674093502

You might be able to get them from somewhere closer. Try lllparts
https://www.lllparts.co.uk/en/

 

[mcbutler]

Well latest step in the saga as car is now garaged.
Replaced all plugs and coils today, all plugs looked nice apart from number 6 which is sooty.
All plugs were removed imediately after a one mile drive no fuel present and no fuel vapour could be smelt, i also took off the oil filer cap and no petrol smell in the oil..
In addition nthe coils removed were Bosch on cyls 1 - 2 - 5 - 6 but 3 - 4 had an unbranded coil with a metal outer case!

The car runs very smoothly now but the original problem is still present

Photos attached for your thoughts fellas.

 

[enuff_zed]

Have you looked at Peter (B21)'s thread on his AY build?
Only today he's posted pics of his coils with an N20 one for comparison.
I may be wrong but that's what two of yours look like?

EDIT: It's actually about halfway down page 6 of his thread.

 

[tiglon]

The number on the second coil photo appears to be for an N46 engine.

 

[Smartbear]

If it’s not incredibly difficult, I’d swap the injector from the sooty plug cylinder & see if the issue moves with it?
Rob

 

[B21]

So you replaced all the coils and all the plugs and now the fresh number 6 spark plug is severely sorted up?

Given that on the N54 many things happen in two banks 1-3 cylinders and 4-6 cylinders this points to a single item out of 6, as opposed to something effecting a bank of 3…

So my guess is an injector going south…

FWIW when I had a single coil misfire the DME switched that cylinder on and boy did it run rough.

Given that often the DME can’t work out what’s going wrong with a component I think you are relegated to doing an A B swap..

I have a bunch of index 9 injectors coming free

 

[mcbutler]

If it’s not incredibly difficult, I’d swap the injector from the sooty plug cylinder & see if the issue moves with it?
Rob

Where would the issue move to? I understand it if a misfire is present by swapping plugs/leads/coils but this is a surging sound that only happens under heavier accelaration.

 

[mcbutler]

So you replaced all the coils and all the plugs and now the fresh number 6 spark plug is severely sorted up?

Given that on the N54 many things happen in two banks 1-3 cylinders and 4-6 cylinders this points to a single item out of 6, as opposed to something effecting a bank of 3…

So my guess is an injector going south…

FWIW when I had a single coil misfire the DME switched that cylinder on and boy did it run rough.

Given that often the DME can’t work out what’s going wrong with a component I think you are relegated to doing an A B swap..

I have a bunch of index 9 injectors coming free

Sorry for non clarity.
The plugs pictured are the plugs I replaced as are the coils, sooty plug is not a new one.
Plugs were replaced with the OEM plug BOSCH ZGR6STE2

I am considering a new set of index 12 injectors regardless, available for around £1100 for 6!!

 

[B21]

Well if you can get them for £1100 for genuine BMW ones that’s a ‘bargain’

 

[Smartbear]

If it’s not incredibly difficult, I’d swap the injector from the sooty plug cylinder & see if the issue moves with it?
Rob

Where would the issue move to? I understand it if a misfire is present by swapping plugs/leads/coils but this is a surging sound that only happens under heavier accelaration.

I meant swap the suspect injector with another from your engine that has no issues, if it’s the injector at fault I’d expect the sooty plug symptom to move to where the injector has been moved to - this would point the finger to the injector.
Rob

 

[mcbutler]

Well if you can get them for £1100 for genuine BMW ones that’s a ‘bargain’

Yes I know, link sent from another very well respected/trusted forum member