[SnapCoupe]

I swear my car decided to hate me this week as I have been experiencing a few weird issues, though this one takes the cake.

After coming out of a corner I got on the throttle in second, shifted into third at around 6500, and continued on the throttle for a few seconds until going into 4th and then 5th. Once I got into 5th I noticed my throttle response felt dull and weird and as I was (thankfully) pulling into my driveway I clutched in and the RPMS dropped to zero. I figured it was a bit of bad gas or something so I tried to restart the car and it sounded exactly like a car with a near dead battery where the starter turns over very slowly. From here I turned off the ignition and checked the codes and the only thing there was a low voltage code, and using the MHD monitor I saw that the voltage was around 8 volts. My battery is an OEM BMW battery bought less than a month ago, so I checked the connections in the trunk and everything was fine. I popped the hood to see if anything was noticeably wrong under there and I was greeted by an electrical smoke smell and a small trail of smoke originating from the driver side of the motor back where the transmission meets the motor.

I walked to my house to grab some jumper cables and before trying to hook them up I tried to start the car on its own once more. This was after about 15 minutes of sitting, and before starting the car I verified that the smoke trail was no longer there. The damn thing fired right up and the voltage went back to normal.

I plan on throwing it up on a rack at work tomorrow and looking for any singe/burn marks where I saw the smoke originating from, but until then I wanted to see if anyone had any ideas as to what this could be. I drove the car this morning and everything seems/feels fine, but given the presence of smoke I refuse to just pretend it didn't happen.

Any thoughts or ideas?

[SnapCoupe]

Update: got home today and noticed a slight chatter or knock while feathering the throttle around 2k rpm.

I have no idea how this would be related to what i experienced earlier, but it is an entirely new sound.

No codes are popping up either.

[CurtisP87]

shot in the dark:

Did you look at the wiring for the heater blower motor? I know I got a recall notice about it a couple months ago for my '11...although perhaps with the blower motor the smell would be more noticeable in the cabin than the engine bay?

Really weird that something electrical would overheat and burn, cause issues, then a while later work normally....Good luck, hopefully it's an easy fix.

[SnapCoupe]

Originally Posted by CurtisP87

shot in the dark:

Did you look at the wiring for the heater blower motor? I know I got a recall notice about it a couple months ago for my '11...although perhaps with the blower motor the smell would be more noticeable in the cabin than the engine bay?

Really weird that something electrical would overheat and burn, cause issues, then a while later work normally....Good luck, hopefully it's an easy fix.

I thought this too, but it didn't seem to be coming from where the blower motor is located.

[CurtisP87]

If you have to drive it to work tomorrow you should keep a fire extinguisher in the car, just in case.

[rich_mane]

I would look at the starter and ground cable first, I'm not sure what else could be in that area that causes an electrical smelling smoke.

Originally Posted by JamesM3M5

Glad you found the problem! The engine ground strap is there to not only ground the starter for cranking but all of the other items that are bolted to the engine - some sensors, the water pump, and the alternator.

I've seen the muffler ground straps on E9x M3s break - they get saltwater in them from the winter and it turns the soft, fine-stranded braided copper hard as a rock. With engine vibrations, you may have a hardened cable that snapped off - typically right at one of the crimp ends.

Sorry I didn't see your request for ground strap location. I couldn't remember where it was anyway, though.

Found that quote from an older thread that suggest the ground cables can break after some salted winter roads. Only thing I could think of is if the ground cable only started to break but was still grounding, only through a smaller portion of wire. Which caused the voltage problems and the electrical smelling smoke, and once it sat for that 15 mins, maybe the cable settled into a better contacting position where it was able to ground properly again.

Did you register the battery after replacing it recently? I don't think the car is capable of fucking itself up this bad if you didn't, but just throwing ideas out there.

[SnapCoupe]

Originally Posted by rich_mane

I would look at the starter and ground cable first, I'm not sure what else could be in that area that causes an electrical smelling smoke.

Found that quote from an older thread that suggest the ground cables can break after some salted winter roads. Only thing I could think of is if the ground cable only started to break but was still grounding, only through a smaller portion of wire. Which caused the voltage problems and the electrical smelling smoke, and once it sat for that 15 mins, maybe the cable settled into a better contacting position where it was able to ground properly again.

Did you register the battery after replacing it recently? I don't think the car is capable of fucking itself up this bad if you didn't, but just throwing ideas out there.

Interesting. I know they don't salt the roads here but i'll take a peek at it. Battery was installed and registered at the dealership.

[SnapCoupe]

Well... I have a very unfortunate update.

Spun a bearing. Oil looks like metallic paint, full of copper flakes. No idea where the smoke would come from or why the voltage dropped, but at the end of the day, I need a motor.

F**K

[CurtisP87]

oooff....

Sorry to hear that dude, thats a kick in the gut...

[rich_mane]

Damn. That sucks to hear man... how many miles did you have on it?

[SnapCoupe]

Originally Posted by rich_mane

Damn. That sucks to hear man... how many miles did you have on it?

82k