Curious why i was running crazy lean with no MAF

[flyfishvt]

I had a problem with my MAF the other day. It would only run with it unplugged. That's all fixed and car is running great. I'm still curious why it was running crazy lean with the maf unplugged.

S52 with stock internals, copper spacer and cutring gasket. It's a Nick G tune on a stock dme. With the MAF unplugged it was idling at 18-19 on my wideband gauge. That's is the only change I made. My logic says with the MAF unplugged I should be idling rich not lean.

I only ran the engine at idle. I didn't dare drive it with it running that lean so I can't tell you any numbers other than idle

[busterhax]

I wouldn't worry about it. There's a theoretical load calculation table used when MAF is unplugged (RPMxTPS axis = theoretical mg/stroke). It may be off, your car may have just been freaking out and trying to figure out what to do, etc.

[Archea]

With MAF unplugged my 320d is rununing very rich. Engine sound is different and torque seams to be available sooner and with biger kick. However, I dont think that there is a corelation btw petrol and diesel maf settings. On my previous 328i I did not realise that maf is malfunctionig at all while on 320d maf function making big difference in performance and engine smoothness.