which fuel injector is leaking?
 

I think I have a leaky fuel injector.

Hard start, especially when warm, better at cold and fine when immediate restart.
Without a gage I KNOW pressure decreases with time at the schrader valve on the fuel rail.

Did NOT help:
replaced "o" rings at injectors (and amateur cleaning of injectors- low pressure air compressor, brake cleaner and 12 volt DC)
New fuel filter
new fuel pump (pro-active maintenance)
engine temp sensor

If I turn key to position 2 and pause (fuel pump runs) and then crank I get an immediate start, so I believe one of my injectors is leaking. How do I know which one?? No error codes on OBD

Looked into replacing all as a set, but hefty price.

THANKS!

This is way too easy to determine.
Remove plugs
The one that shows up black like a lawn mower plug is the cylinder that is running rich and or has the injector that is leaking.

Give me a sec and I will give you a link to a few plug shots show you will know what good is and what to look for....

Here is the image that you need. Good visual but it is related to small engines and carb equipped applications.
http://www.tuningmatters.com/how-tos...retor-setting/

Here is more detailed info on plug reading.

https://www.ngksparkplugs.com/about-...d-a-spark-plug

THANK YOU!
will check my plugs this weekend

This is easy to determine - pull the fuel rail leaving all injectors attached, prime the fuel rail in position 2 - leave a colored shop rag underneath the plugs -

Come back after sitting for a few hours - the ones that leaked onto the rag (if one or multiple) are the ones that are leaking internally - they must be replaced if they are leaking down, no rebuilding will fix them.

Go with OE injectors for obvious reasons, there was a thread on E46F or BF showing that BMW updated the Siemens or Bosch injector later on in the E53 lifecycle, apparently there was a faulty design that could leak internally -

Dorin (Doru) on this forum went through this with his E39 and could chime in to help - he ended up replacing all 6. Yes its about $600, but you will never have injector problems for the rest of the vehicle's life most likely.

:iagree:

Good tip!

Thanks!
Is VDO the same as Siemens? About $100. "Genuine" BMW at $144.

Cross referencing Genuine BMW part # 13537546245 -

I'm under the impression that the 2 companies are owned wholly the same so my inference is to say to get the VDO injectors (new) -

NOT fully understanding this......
initially key in #2 gets pressure at the schrader valve (gas comes out like a geyser)
With the key still at #2 after time and that geyser is released, then there is hardly any pressure. SO pump does not run continuous in #2, only initial run/up pressure??

Back to my test, I build pressure with key in #2, wait and after 3 min or so there is NO gas on the rag and the pressure at the schrader valve is a tiny "poof" sound and NO gas released.

SO I am leaking pressure somewhere else??
(and its dry at the fuel rail connection at back)

THANKS!

That is correct, fuel pump runs initially just to power up the pressure but turns off if the engine does not start. Once the DME determines that the engine has started or is cranking, the DME will command the fuel pump on.

Turn off the ignition switch, wait and turn it to position number 2. Wait, turn it off and turn it back on to position no 2. Turn off the ignition switch and check the Schraeder valve again. I bet you will have a geyser of fuel when you depress the valve.