N55 MEVD1726 - 2A15 Low Voltage Short, Misfires, Failed DME?

[Sanfordev]

Good Morning 1Addicts,


Please move if this is in the incorrect section. I've been chasing a problem for several weeks now. Thrown a bunch of parts at the car, and nothing has seemed to fix the issues. I do all my own work, so I'd prefer to fix this myself than to bring to a shop. I'm hoping that with the knowledge and input of the members here, I can get her running good again!


I've only seen one similar post to mine in regards to the MEVD1726 DME - https://www.n54tech.com/forums/showthread.php?t=62329


The car will drive just fine, with no codes, and all logging within acceptable ranges, as long as I keep throttle under ~50%. Anytime I go WOT, I almost immediately throw this code and get a full engine light. Only way to clear is pulling over, full restart and clear codes. So High Load, full on boost situations. Logs show healthy until event happens and throttle cuts.





Background of the car:
-N55 with MEVD1726 DME
-Full bolt ons
-Pure stage 2
-Stage 2 high pressure fuel pump
-Stage 3 low pressure fuel pump
-Upgraded fuel lines
-Custom tuned by wedge


Issue first started showing up when running my e50 tune. Went back to previously completed 93 tune which has 0 corrections, and runs flawlessly. Still throws the code under the same conditions on this tune now, when previously didn't. Leads me to believe its mechanical and not tuning related.


What I've done / replaced in attempt to fix:
- All 6 NGK spark plugs gapped at .022"
-Swapped Coil packs, problem remained on Cylinder 6
-Replaced all 6 coil packs with brand new Delphi Coil Packs
-Replaced all 6 Injectors
-Replaced pressure regulator
-Smoke tested, no leaks up to 26psi (My max target boost)



BMW Master tech I spoke with says it wouldn't be the wiring harness, or else the code would persist at all times, and not just under high load events.


I ran the Ista test procedure which gives the following options. Already tried every option except the last - DME Replacement.









Per recommendation of another forum, I am going to pull my DME and check continuity on the mosfets. Any other recommendations?

[houtan]

Where are the logs when the codes get thrown?

[Sanfordev]

Originally Posted by houtan

Where are the logs when the codes get thrown?

Thanks for your response! I didn’t post logs because Steven said they were healthy up till the throttle cuts which is the same timestamp I throw the code. But here they are:

ps2 93 v3 - 3rd gear CEL
ps2 e50 1.1 3rd -> 5th CEL
ps2 e50 1.1 3rd -> 5th CEL #2

Those are my most recent logs that have the event occur. I have pages of healthy logs previous to this fault if you look on my account.

[Tallicia]

What did you uncover on this? something simple? a relay? or the DME failing?

[bbnks2]

check the wiring harness?

[Sanfordev]

This is a year old thread..

But I ordered a cloned dme and the problem persisted. Finally solved it by replacing the dme wiring harness.

[Tallicia]

Thanks for the update! I had to replace my DME and clone it and all is good now. I had done the wiring test/replace first.

Finding someone or someplace that can open the MEVD17.x DME for testing and repair/replacement of a few IC pieces is going to become very important for these things in the very near future. I guess these were engineered with only a decade lifespan. :<

It seems quite ridiculous that a $2000 DME needing a few dollars of chips desoldered and new ones soldered on becomes complete junk.