Completed M50 swap----rough idle...sometimes

[Gras rauchen]

Just completed the bimmerworld m50 swap. When i fired her back up i got a real low/rough idle. Most of the time it bounces between 500-600 rpm sometimes dipping low enough to stall the vehicle.


Now i did clean my IAC and throttle body out with carb cleaner. So i figured they might just need to relearn.

Some times, like right this instant, it idles at a smooth 700-750 but will suddenly revert back to bunting betweeb 500-600.

I double checked my 3 vacuum lines under the manifold. I got the bigger one thats attached to the solenoid thing attached to the icv connector. I got the other two smaller lines Teed into the manifold.

Also the car run great, just idles funny.

I pulled some codes.

P0170 - FUEL TRIM BANK 1

P0412 - SAP SWITCHING VALVE A CIRCUIT

P0155 - O2 SENSOR HEATER CIRCUIT BANK 2 SENSOR 1

P1188 - FUEL CONTROL (bank 1 sensor 1)

P1189 - FUEL CONTROL (bank 2 sensor 1)

Is the sap switcing valve the thing that plugs into the fuel injector wiring harness? (I drilled a hole through the manifold webbing in order to hook it back up)

These fuel trim and fuel control codes have me thinking i may have switched the o2 sesnors on the intake manifold (even though i marked one sensor, it still has me thinking i did it wrong.)

The other part of me thinks i have a faulty IAC thingy (or made it faulty by messing with it) and i want to replace it because i hear a buzzing wheb im low idling and the buzzing goes away when its smooth idling.

I replaced the IAC hose because my old one was kinked but that did not help my idle.

Now when i clear the codes the O2 sensor code comes back immediately

[AJLM34A]

Carb cleaner is made for cleaning old fuel that turns to varnish and gums up carburetors. It is a very harsh cleaner. Brake cleaner would not be a good choice either.

Throttle body cleaner would have been a better choice.

[Braymond141]

The swap isn't done correctly or you're not disclosing everything you did in the process.

[hakentt]

M50 swap with OBD2 codes? Why is this in M3 section?

[Gras rauchen]

The swap could be incorrect. I plan to pull everything out underneith it to double check everything. I think ill do it tomorrow.

- - - Updated - - -

Because its on an M3

[Braymond141]

The swap could be incorrect. I plan to pull everything out underneith it to double check everything. I think ill do it tomorrow.

- - - Updated - - -

Because its on an M3

Hankentt is a known %#@*& idiot. Just ignore him.

[Gras rauchen]

So the culprit was a split in the ccv hose. So sometimes it would leak. New hose and she idles smooooooth as butter