What are the side effects of replacing the MS43 DME ECM?

[Mike1261]

My 2006 X5 is a Canadian vehicle that we imported to the US.

I reprogrammed the ECU to switch everything to Miles/Fahrenheit, as well as enabling some conveniences like auto-lock door locks when driving.

I have a persistent O2 sensor error, and while I'm hoping it's a wiring problem, I know it could potentially indicate a problem with the MS43 DME ECM.

If I grab a used one off eBay, can I just plug it in and everything is the way it was? Or do I lose some of the programming I did? Or does the replacement need to be somehow matched to the vehicle?

Thanks!

[Clavurion]

What are the exact codes you are having? Most of the pre-cat lambda errors on M54 engine are caused by air (vacuum) leak.

You can't just change DME. Immobiliser data on DME has to match your vehicle or it won't allow engine start.

[Mike1261]

Originally Posted by Clavurion

What are the exact codes you are having? Most of the pre-cat lambda errors on M54 engine are caused by air (vacuum) leak.

Attached is the error code screenshot I'm getting on INPA.

It's been this way since I bought the car, the O2 sensors have been replaced twice, both times with Bosch.

[Clavurion]

Originally Posted by Mike1261

Attached is the error code screenshot I'm getting on INPA.

It's been this way since I bought the car, the O2 sensors have been replaced twice, both times with Bosch.

Most likely air leak causing too lean mixture. DME is trying to give richer mixture according to lambda signal but not able to do it.

Typical air leak causes:
*Rubber boots between MAF and throttle valve
*CCV hoses/separator
*Rubber plugs at the rear end of intake manifold
*DISA valve

[Mike1261]

Originally Posted by Clavurion

Most likely air leak causing too lean mixture. DME is trying to give richer mixture according to lambda signal but not able to do it.

Typical air leak causes:
*Rubber boots between MAF and throttle valve
*CCV hoses/separator
*Rubber plugs at the rear end of intake manifold
*DISA valve

The boot that attaches to the throttle body has been replaced.

New CCV system.

Replaced the O Ring on the DISA Valve and cleaned it thoroughly.

So I'll check the rubber plugs at the back of the intake manifold. Hopefully it's as simple as that lol.

If there's any other common vac leaks you can think of I'm happy to check those too!

[Effduration]

Many sources of possible vac leaks. See if you can borrow a smoke tester or pay a mechanic to do a smoke test for you.

Forget about replacing the DME.

[Mike1261]

I went and took a look at the engine bay for a min, and I was reminded of two erroneous vacuum lines that I've never figured out what they were for or where they're supposed to go.

If someone could tell me what these are supposed to connect to, that would be AMAZING and I will have ridiculous amounts of gratitude :-D

Both these lines are hard plastic lines with permanently formed bends.

The first one: It goes under the intake towards the front where the CCV system is on the Driver side, forward of the DISA Valve. When I replaced the CCV I noticed this line loose and couldn't see anywhere it would attach. I meant to post a pic of it a year ago to see if anyone had any ideas. It has a 90 degree bend in it aimed in toward under the intake towards the CCV system. I pulled it out from where it sits for the sake of the photo.

Second Photo: This is attached to the Oil Dipstick Tube. I don't know where it goes downwards, and the top of it is a hard U shape bend and isn't connected to anything.

Previous owner was a backyard mechanic that did lots of ridiculous things to this car, none of which make any sense to me nor fixed anything that needed to be fixed. It's been a real learning adventure, as it's my first BMW that I actually work on myself.

[Mike1261]

I read something that told me the tube on the dipstick is the Transmission Vent Tube and doesn't go anywhere.

Just trying to figure out now what the front one is for, forward of the DISA Valve.

[Clavurion]

Check this recent thread with lot of pictures of M54 hoses.

https://xoutpost.com/bmw-sav-forums/...tion-help.html

The hose on the dipstick tube is most likely front diff vent hose and is supposed to be like that.

[Mike1261]

Originally Posted by Clavurion

Check this recent thread with lot of pictures of M54 hoses.

https://xoutpost.com/bmw-sav-forums/...tion-help.html

The hose on the dipstick tube is most likely front diff vent hose and is supposed to be like that.

Oh boy :-( There's a whole mess of hoses that go under the intake. I feel like I'll never figure out where all that stuff attaches without removing the whole intake. Wonder how big a job that is... Doing the CCV was a pain in the butt on its own lol.