New HPFP, update software, new spark plugs, injectors, headlights and O2 sensor

[///M Boss]

Hi
Just got my car back from BMW, they had it for 2 weeks and didn't know what was wrong with it. I already knew since I bought the BT scan tool. I tried hinting it out but he didn't believe me so they ended up changing alot of things that I believe were not necessary. The check engine light was on from the faulty O2 sensor and cylinders misfiring. The car discharged black smoke from the exhaust on heavy acceleration. I was told by the tech working on my car that it was from the built up fuel in the cylinders. Under normal driving the car would start to shake and stutter around the 4-5k rpm range with major power loss and finally the car went into limp mode couple of times. The tech even had to contact BMW head office. They finally replace the 02 sensor and the check engine light was gone. Now the car runs like a dream it feels a little faster now and I find that new software makes the car's power band so smooth but it can be just my perception. I am very happy with the car it runs like new again and it feels effortless to get the car going at a quick speed.

[shodanusmc]

built up fuel in the cylinders.....and the o2 sensor fixed that?

[///M Boss]

I guess the change of injectors and spark plugs fixed the misfiring issue

[KingOfJericho]

Fuel can get built up? That doesn't seem to make any sense as it would be burned off. I can see carbon buildup but not "fuel."

[///M Boss]

yeah my mistake, it was a carbon built up. What your saying does make sense, it was blogging at start up and runing too rich. I always have short drives ( 3-5 kms) and the engine usually never warms up to optimal temp.