2010 328xi

[Dave Boudreau]

Ran diags came up with codes 29d1,combustion misfire cyl 5,  29d2 combustion misfire cyl 6 and 29cc combustion misfired several cylinders. Notice smoke from back of motor but will go away if I turn ac on. Any ideas

[Greydog]

Morning David

Welcome to the Forum

Misfire's can be caused by a number of things as you are probably aware. Is your diagnostic program BMW specific? 

Misfire, could be plugs, coil packs, loom to the coil packs, DME fault (BMW Specific Diagnostic will help), fuel delivery (injector leak). The smoke may be unburnt fuel, when the load is increased (AC on) it gets burnt off?

If you haven't already I would do the simple free stuff first. Swap coils around see if the misfire moves. Inspect the plugs and change if needed. Check carefully the loom for signs of wear/rubbing which could indicate a short under load. Clean all connectors with a good Electrical Contact cleaner and re-seat. Check the induction side for any air/vacuum leaks.

If you aren't aware here are a couple of web sites that may help. 1. www.realoem.com a BMW online parts list so when buying stuff you know it will fit, Put the last 7 digits of your Vin into the search box it will bring up your model. 2. www.newtis.info a BMW Technical information site Dealers use this for repair and replacement information, same search criteria. www.pelicanparts.com great "how to's" with pictures 

Hope I have helped not hindered

Dave