Car Owners Hub UK - Built by Drivers, for Drivers

The E90 325i N53 from BMW

Based on the data I collected when investigating mixing concerns, I can corroborate the following:


1. The DME is showing that Bank 1 is running rich, with fuel being pulled at -13% to try to compensate, according to Current, Short Term, Long Term, and Load Multiplicative.
2. It appears to be a mechanical issue, possibly due to worn needles or seats, because all six injectors are electronically reporting the same charge levels.

So, how can we determine which of these three is really at fault?

Pulling the plugs and leaving the car parked overnight were both attempts. Not only do none of them seem especially damp, but I also failed to observe any puddling above the pistons. There was a faint fuel aroma that permeated the room, but it wasn't overwhelming.

Injector Leak Down Tests within ISTA have been recommended; in these tests, the fuel rail is pressurised to 200 Bar while the engine is off, and the rate of pressure drop across each injector is monitored.

The only problem is that no matter how much I search, I still can't locate this function within ISTA.

Would you have any more recommendations?

Even if I haven't actively sought it out, I also can't claim to have observed that experiment.
Even with the engine turned off, it will not be able to pressurise the rails to 200 bar because the electric pump can only produce about 5 bar of pressure, and HPFP must be running for this to happen.

Without a doubt, the camshaft is what drives the HPFP .

By "LPFP," I meant exactly that. That can be activated by turning off the engine for twenty seconds.


It will still not reveal which injector is leaking even if I go back one screen and examine the high/low pressure.

Do you have any suggestions?

Prior to this, I had taken them off a n43, attached them to rail without them, and then pressurised the system. Also did it last week with a N18.
Link them up, turn the motor on to generate pressure, and then go away to check for a leak.

That was something I had thought of as well, but I'm naturally apprehensive because I've never dealt with injectors before.

As I've noticed over the past few weeks, my car is getting on in years where seemingly fine parts start to malfunction the moment they're disturbed .


Also, after looking at the prices of replacement injectors, I'm not sure it's worth it to spend much more money on.

Yes, it does run, and it's not too horrible at the moment.

To top it all off, these injectors are subpar and somewhat pricey. I have just purchased a C-Class Estate Auto for my wife, so she will soon be moving on.