2A15 Low Voltage Short, Misfires, Failed DME?

[tsanford]

Good Morning SpoolStreet,

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!

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.

Before I end up buying a new DME, has anyone here ever dealt with these issues and codes before? Any other solutions or things to try before DME replacement?

 

[NoQuarter]

Which DME is this?

This could be MOSFETs in the DME.

Can be replaced fairly easily and cheap.

 

[ajm8127]

From two different sources code 2A15 seems to be related to DTML issues.

BMW Fault Code Lookup - BMWFaultCodes

https://www.peakeresearch.com/manuals/FCX3-manual%201.0%20NA.pdf

I don't know what is right, but there appears to be a dependency between your interpretation of the code and other sources.

That said, a problem with injector 6 low side activation short to earth sure sounds like an electrical problem with the DME.

According to TIS, each injector has a high side and low side switch. There is also another component shown by a rectangular box and an arrow indicating that net goes to a different location. I suspect the boxes are resistors and the arrow goes to some sort diagnostic circuit that detects the current flowing. If that code description is to be trusted, it sounds like there may be a problem with the low side switch on injector 6, or the related circuit.

I agree that the MOSFETs in the DME should be diagnosed if this is an MSD80. All you need to do is pry off the DME cover and use an ohmmeter to check the MOSFETs. There are some videos on YouTube.

For instance:

Make an attempt to keep yourself ground to limit static discharge. MOSFETs in particular are sensitive to static discharge because of the thin metal oxide layers in them.

 

[tsanford]

Thank you both @NoQuarter and @ajm8127 for your quick replies.

Unfortunately I have the MEVD1726 DME. I am fairly experienced with soldering, so I could repair if I had more details on parts, pinouts etc.

 

[ajm8127]

Ok, I take back what I said about 2A15 relating to DTML.

The injector schematic looks the same.

MOSFET failures are common in the MSD80, but they could still happen in other DME versions. If you are comfortable with taking the cover off maybe you could find the low side switch for injector 6 and test it. What the trouble code is describing is a typical failure mode for a MOSFET.

What year and chassis is your vehicle?

 

[tsanford]

Ok, I take back what I said about 2A15 relating to DTML.

The injector schematic looks the same.

MOSFET failures are common in the MSD80, but they could still happen in other DME versions. If you are comfortable with taking the cover off maybe you could find the low side switch for injector 6 and test it. What the trouble code is describing is a typical failure mode for a MOSFET.

What year and chassis is your vehicle?

2013 E82 UC93

I opened and bench-flashed my DME 2 years ago, so I won't have any issue opening it up again!

 

[ajm8127]

This should be the wiring diagram for the fuel injectors.

newTIS

You'll need to use a multimeter to trace pin 17 of A6000 on the DME back to a MOSFET or other type of electronic switch on the PCB. Once you've done that the part will need to be identified and tested.

Take pictures and ask questions if you need help.

 

[tsanford]

Thanks @ajm8127, I'm gonna pull out the DME and check the mosfets for continuity as the guide videos shows. Will update with pics and details.

This should be the wiring diagram for the fuel injectors.

newTIS

You'll need to use a multimeter to trace pin 17 of A6000 on the DME back to a MOSFET or other type of electronic switch on the PCB. Once you've done that the part will need to be identified and tested.

Take pictures and ask questions if you need help.

 

[tsanford]

Attached are some logs:
ps2 93 v3 - 3rd gear CEL
ps2 e50 1.1 3rd -> 5th CEL
ps2 e50 1.1 3rd -> 5th CEL #2

 

[tsanford]

Welp I paid for a brand new DME and it did not fix the problem. Same codes almost immediately. As a temporary work around I provided a secondary ground from the 5/6 ground to chassis and the code hasn’t popped up since.

 

[tsanford]

Problem came back 2 days later with the new DME. Except this time its now alternating codes

2A15 - Injector, Cylinder 6, activation, low voltage side, short circuit to earth
and
2A51 - Injector, Cylinder 6, activation: Line disconnection.

Not at the same time, 1 or the other.

 

[NoQuarter]

Frustrating for sure.

Measure ohms of cylinder 6 leads?

 

[tsanford]

Frustrating for sure.

Measure ohms of cylinder 6 leads?

I did the ohms test on cylinder 6 wiring, but that only tests continuity. I did not test for voltage drop as my volt meter pins aren't thin enough.

I ordered a new wiring harness, so in a few days I'll know if thats my solution. Car acted up more than usual after it rained the other day which leads me to believe wiring and condensation / water getting into the connections.

 

[ATL-IS-N54]

Subbed - I just started having the 2A15 code with injector 6 short to ground on low voltage side - right after refueling with E30 mix... had zero issues until RIGHT after I put the gas in... was only on wot then it started doing it on sport mode in any throttle and in non sport mode with over 50% throttle - kills #6 pulls boost and shows limp mode - im able to clear the codes and get cylinder 6 firing again while rolling down the road by just clearing the codes... I’ve read some gas cap stuff and some DMTL stuff related to 2A15 but not the same description of short to ground on low side -
2013 FBO N55 135i E30 tune MHD DCT7
Best of luck

 

[matt cangie]

Have you checked your alternator? Most auto supply shops will test it for free. Could be: under load, it can no longer keep up with the high demand you're asking from it. Remember, injectors, coils, fuel pumps, lighting, water pump, etc... all need precise, stable voltage to work. It would also explain it only happening during high performance scenarios. I'd say check you JB4 to monitor voltage during a pull but you don't have one(?)