[atzekovsky]

Hey everyone... Please help..

Let me give some background on how the issue started.. I would be driving normally and suddenly the car would lose (most) electrical and engine power, the iDrive would shut off, and dash lights up like a Christmas tree. This would usually just be for a few seconds and everything comes back to life.

A week ago, I went to start my car before work and it was misfiring on start.. I just restarted a few times and it was fine. Life has been very hectic so I just pushed that aside too but a few days ago I was driving home and got heavy misfiring while idling at a traffic light, SES, then after a few seconds, engine lost most power and was barely able to stay on. I managed to get it home by literally starting it up, driving in first for 15 seconds before it nearly died, turning it off, starting up, rinse and repeat (nightmare).

FYI I have all the basic mods.. JB4, inlets, outlets, charge pipe, DCI, Intercooler.. even replaced turbos that were bad with OE+ a year ago..

Prior to this happening, I pulled codes with JB4, and I had a ton.. but after research on this forum I narrowed it down to a fault in the BSD circuit caused by the water pump. The past few weeks when I turn the car off I could hear an electrical motor whirring sound and I know the pump was overdue.

So I take it to my mechanic friend who is very good and I have used him for years.. he replaced the water pump and all of the laundry list of codes did go away, along with the sound I've been hearing, except for misfires on 4,5, and 6. He did compression test, swapped coils, injectors, plugs, all the usual stuff.. but then he found there's just no power going to the fuel injectors on 4, 5, and 6.. and he thinks it's the DME. I'm convinced it's gotta be something stupid that has to do with the electrical system or is related to the issues I had with the BSD circuit..

What do you guys think has anyone run into this before? I've seen too many posts where it turned out the DME was done and it was something else so I would sincerely appreciate any advice before I go to the dealership for them to start robbing me blind replacing one thing after another.




edit: turned out to be the DME. I mailed it into the-ecu-pro and decided to rule that out before I started throwing parts at it. Turned out to be a broken pin.. they soldered on a new one, sent it back, car is perfect no codes..

[SlowE92]

Originally Posted by atzekovsky

Hey everyone... Please help..

Let me give some background on how the issue started.. I would be driving normally and suddenly the car would lose (most) electrical and engine power, the iDrive would shut off, and dash lights up like a Christmas tree. This would usually just be for a few seconds and everything comes back to life.

A week ago, I went to start my car before work and it was misfiring on start.. I just restarted a few times and it was fine. Life has been very hectic so I just pushed that aside too but a few days ago I was driving home and got heavy misfiring while idling at a traffic light, SES, then after a few seconds, engine lost most power and was barely able to stay on. I managed to get it home by literally starting it up, driving in first for 15 seconds before it nearly died, turning it off, starting up, rinse and repeat (nightmare).

FYI I have all the basic mods.. JB4, inlets, outlets, charge pipe, DCI, Intercooler.. even replaced turbos that were bad with OE+ a year ago..

Prior to this happening, I pulled codes with JB4, and I had a ton.. but after research on this forum I narrowed it down to a fault in the BSD circuit caused by the water pump. The past few weeks when I turn the car off I could hear an electrical motor whirring sound and I know the pump was overdue.

So I take it to my mechanic friend who is very good and I have used him for years.. he replaced the water pump and all of the laundry list of codes did go away, along with the sound I've been hearing, except for misfires on 4,5, and 6. He did compression test, swapped coils, injectors, plugs, all the usual stuff.. but then he found there's just no power going to the fuel injectors on 4, 5, and 6.. and he thinks it's the DME. I'm convinced it's gotta be something stupid that has to do with the electrical system or is related to the issues I had with the BSD circuit..

What do you guys think has anyone run into this before? I've seen too many posts where it turned out the DME was done and it was something else so I would sincerely appreciate any advice before I go to the dealership for them to start robbing me blind replacing one thing after another.

Check wiring to 2nd bank 02 sensor. If the issue sticks to that bank only then it's usually not plugs or coils or injectors. Is it throwing a misfire code for the 3 cylinders? More than likely a wiring issue or 02 sensor. Could possibly be DME

Edit: Also check fuse in glove compartment it's a 30a fuse.

[atzekovsky]

Thank you!! Will try this and report back. There is a misfire code for all 3 cylinders.

[SlowE92]

Originally Posted by atzekovsky

Thank you!! Will try this and report back. There is a misfire code for all 3 cylinders.

What code is it throwing?

[atzekovsky]

Originally Posted by SlowE92

What code is it throwing?

P0304, P0305, and P0306

[SlowE92]

Originally Posted by atzekovsky

P0304, P0305, and P0306

I'd lean towards bad 02 sensor. Does it only occur while driving? Can you post a log so I can see fuel trims?

[atzekovsky]

Originally Posted by SlowE92

I'd lean towards bad 02 sensor. Does it only occur while driving? Can you post a log so I can see fuel trims?

I would I usually use the JB4 app on my phone but it's not connecting for some reason which supports the DME theory. I had it towed to the dealership to see if they can rule that out.. if they do, O2 sensor will be the first thing I try

[BRG_N54]

Originally Posted by atzekovsky

Let me give some background on how the issue started.. I would be driving normally and suddenly the car would lose (most) electrical and engine power, the iDrive would shut off, and dash lights up like a Christmas tree. This would usually just be for a few seconds and everything comes back to life

This all sounds exactly like a bad voltage regulator. Have you or your expert mechanic bothered to check the alternator voltage when the car is running? I usually recommend the hidden gauge menu for this task, as it's built in and just takes a few button clicks. It should be between 13.5V-14.5V, if left to run in an overvolt state it can cause permanent damage to some of the delicate circuitry, including DME, BSD, etc. The voltage regulator is a consumable item, much like the battery, because it has brushes that wear over time. Only use Bosch for this part.

What happens when you run the car with an out of balance electrical system is, it will begin to turn electrical systems off, one at a time, beginning from least impactful to most. This usually ends in the water pump being shut off and then the car loses power greatly and overheats. The motor has been stressed even more with your aftermarket parts and those could also be contributing factors, accelerating any terminal faults.

[lowrydr310]

Check the voltage regulator like what BRG says.

Are you familiar with the MSD80 MOSFET transistor issue? I don't know how common it is, but here's a lengthy thread. The guy who started it has the same misfire codes you have:

https://www.e90post.com/forums/showthread.php?t=734162

[atzekovsky]

Hey guys I just heard back from the BMW dealership.. it's giving an internal code 30BB. They think that there is a bad injector ignition circuit transistor on the DME and that this was caused by bad injectors or coils. I recently did my coils but somehow 2 of them have rust on them? I did replace 1 injector on cylinder 1 and it's index 12.. the rest are like index 2 index 7, kind of just a mix. So they recommend replacing all injectors and coils prior to either replacing the DME or shipping it off to a recommended company for repair.

What do you guys think? It seems like a plausible problem but something in my gut is telling me it's a bad ground somewhere based on other posts on this forum. Where would I check for a bad ground? Because that would seem consistent with the (apparently) unrelated issues I had with the BSD circuit

[ChuckW]

I think Lowry has the right idea. This is the best video on the DME Mosfet replacement: