2010 X5 35d - won't start after injector replacement
 

Had a shorted injector and drove the X5 home to fix it.

Just replaced the #5 injector, coded it using INPA, full charge battery, fuel flowing through low pressure line, primed the system several times (ON for 1min), lots of cranking power, but the engine won't fire.

INPA error code read confirms no stored codes.

Only thing I can think of is computer isn't pulsing the injectors but I don't know why.

Any troubleshooting suggestions are much appreciated!

Wondering why did you replace the injector no.5? Your code 4B99 in your other thread refers to the whole bank 2 activation and it points to your injector wiring or DDE .Moisture may have damaged and shorted your negative wire which is (i think )common to all bank 2 injectors (4,5,6).Check continuity on the injector wiring harness by unplugging it from the junction box.

My investigation of code 4B99 revealed that the DDE is detecting a short circuit in an injector on bank 2. Not that different from the ISTA fault description. The ISTA "action in service" puzzles me and appears to indicate that the injectors couldn't be the cause of the short circuit.

The guys on this forum highlighted the partition water leakage issue for me and sure enough, I found lots of corrosion around injector #5 and on the feed line.

This all started because the engine would suddenly die when I went over ~70% throttle. Eventually the engine died in the middle of the road with no throttle and it would not restart. Knowing that the #5 injector was somewhat shorted (possibly intermittent), I disconnected injector #5 from Bank 2 and the engine fired up right away. Ran a little rough but I was able to drive 2kms home and avoid a tow.

I then disconnected all the Bank 2 injectors and measured the resistance between the two pins, pin 1 and ground, pin 2 and ground. The resistance between the two pins was consistently across all three injectors (~210Kohms) but only injector #5 measured about 5Kohms between one of the pins and ground. That measurement was ~infinity (beyond my meter's measurement capability) on the #4 and #6 injectors.

And that's why I replaced injector #5. :thumbup:

Sorry let me make sure I understand: what exactly did you measure? Are these measures across the pins ON THE INJECTOR? ON THE HARNESS? Between each PIN and the GROUND point on the chassis?
The first part of the sentence "The resistance between the two pins was consistently across all three injectors (~210Kohms)" seems to contradict the second "only injector #5 measured about 5Kohms between one of the pins and ground. That measurement was ~infinity (beyond my meter's measurement capability) on the #4 and #6 injectors."

Not an expert in any way but if your single injector had short then DDE would have thrown single injector activation error code rather than whole bank 2 activation error code.I would still inspect bank 2 wiring harness.

I think that since like you said injectors on each bank share the ground an internal short in one of the injector could short the entire bank, no?

Can't say for sure because if you look at the attached SIB,it actually states single injector fault codes.Its weird:dunno: Now I remember bluedragon had same 4B99 code and in the end ,he had to replace all 3 (bank 2) injectors.

Sorry about the ambiguity! I measured the injectors. Ground = injector body/ battery negative.

I just measured the other pin to injector body(ground) on the bad #5 injector which I never got to when it was still in the head. 240 ohms!

Both good injector pins are electrically isolated from the injector body/ground. Makes sense because the DDE injector output is active low (supplies a ground).

Good point. What if the +12V side was shorted to ground (240ohms) and BMW fused each bank, then it couldn't detect the individual injector short in this scenario.

Perhaps the 240ohm resistance I measured on the bad injector is the +12V side(pin) of the wire harness and the 5Kohms resistance is the side(pin) going to the DDE. 240Ohms is only 50mA so not enough to clear a fuse but perhaps the DDE monitors that side(pin) also?

I was lying that -ve is shared between all injectors of bank 2.After looking at wiring diagram it appears that DDE supplies each injector +ve and -ve separately.So its puzzling why DDE is throwing complete bank 2 activation code unless all 3 injectors are bad:dunno: