Originally Posted by rmr2122

I smoke tested this morning for over 10 minutes and found no leaks at all.

The airflow at idle on the new VDO MAF was 7.28 g/s. I swapped back to my old Siemens MAF (which I replaced preventively, so luckily I kept it just in case I needed a spare). The airflow at idle on the OEM BMW Siemens MAF is 4.48 g/s. Which one is correct or better?

I was getting NEGATIVE 8.8-10.5 short term fuel trims with the new VDO MAF at idle installed. With the OEM MAF reinstalled I am getting short term trims that fluctuate between. -0.80 and + 0.80. When I increase to 2500 rpm, the short term trims go to between +3 and +5.

Maybe the new VDO MAF is bad? I guess time will tell if the SES light pops back up. I'd like to investigate this issue further using fuel trims and now with my old OEM MAF reinstalled. What should I do next?