Rough idle and misfires on start up

[Crystalmr]

I have a 2007 bmw 328i. I am no mechanic at all. But decided to try to figure out what is going on with my car. I have the codes for random misfire, and all cylinders misfiring, and also P0040. After cranking, it will misfire a lot, then it will rev up. And goes back down. And idles normally.

[Crystalmr]

[BimmerBreaker]

I'd start by making sure the battery is good. Seems to have a LOT of codes and errors

[328 Power 04]

So, who touched it last? Please provide all the history, when it started, what has been done, etc.
P codes suck, but P0040 is quite specific for switched oxygen sensor connectors.

Can you get a better scan with a BMW oriented tool?

[Crystalmr]

We replaced the battery like a month ago.

- - - Updated - - -

I don't have access to a better scanner sadly. But I don't know who last worked on the car. We got it like 2 months ago. Has had these codes since I got it. I researched fuel trims some. And one bank is like -30 and the other is like 29. I've read that that is a sign that the pre cat O2 sensors are swapped. But I've changed the spark plugs, replaced two coil pack, changed the oil and filter and cleaned the vanos solenoids because I had p0012 pop up once and cut the car off and crunk it up and the code disappeared. Same with code p0015.

[Crystalmr]

The freeze frame data for p0040 is...
Closed loop
Load is 72.5
Stft1 -30.5
Ltft1 -0.8
Stft2 29.7
Ltft2 1.6
RPM 855
Ignition timing for cylinder 1 -9
Throttle position 20.4..

[328 Power 04]

The oxygen sensors are very likely swapped and will make a mess of your engine.

Mark them as is now, and swap them around. If it gets better, then you know.


Alternatively, disconnect one, and see what code gets set. If the error says bank 2, but the wire is actually going to bank 1, then for sure they're swapped.

[Crystalmr]

Turns out whoever touched the car last had crossed the wiring for the plugs. I switched them. And have no more misfires and the service engine soon light even went off! I had been researching this for a little while but didn't want to actually do it before someone could confirm it for me.