ag2009

Greetings all, I've learned so much from others questions here, and its finally time for me to ask one of my own.

2009 528i 85k miles, just had transmission pan/gasket/filter/fluid, and transmssion adaption performed for a different issue (car was kinda thumpy during up/downshifts) tranny seems fine now, but today something odd happened. Car had sat overnight, so it was a cold start. Pulling out of my driveway, no issues whatsoever, approx 1/8 mile away, there is a 90 degree right, that is up a fairly steep grade. When I go around the corner (maybe 20-25mph), and started uphill, the car downshifted from 3-2 (I think). It felt like it struggled for power during the downshift, and upon giving it more gas, you could feel the engine seemed to be missing.I made it to the top of the feel under what felt like fairly reduced power, and upon coming to a stop. the engine was still running really rough (like half the number of cylinder rough) I put it in park, reverse, neutral, same rough running. Turned the engine off, and waited maybe 5 seconds. After a restart, it felt totally fine again, smooth and quiet. It's been fine the rest of the day.

No errors appeared in the check screen, no lights, nothing.. My initial thought is a sensor somewhere (yeah vague) or bad plugs.. Because it was running roughly after I stopped, and cycled through the gears, I really inclined to think it's isolated to the engine.

Any ideas?

Thanks in advance

ag2009

After a bunch of online research, I think 1) I'm going to stop by my indy, and see if any codes exist, 2) replace the plugs and coils, as it sure seems like a coil-based missfire. If anybody has any further input, let me know.

Dan

JuniorB

HI,bad coils are either good or bad,one it starts it stays like that till its replaced,cold engines,to my knowledge, may hiccup,not uncommon,depending how bad your misfire is and if it is that. Have you had your air filter checked,map sensor cleaned,or throttle body cleaned? I've done this and has made a world of difference. Hope this helps

ag2009

I appreciate your input, My misfire was only when cold, and under a load (going up a hill) I pulled and cleaned the MAF sensor, and put in new plugs and coils. The old coils were original to the car, and had a date code of Dec, 08. The plugs were pretty dark since they'd never been changed either. After the change, the car is running strong, and the misfire seems to have gone away, or at least I haven't been able to make it come back...either way, I'm happy.