I put on a K&N ram air onto my 2003 corolla. Yes i know the results are questionable... My question is does this have any affect on the mass airflow sensor (ie. is there known to be any problems, any recalibrations needed, or what?
thanks
The main issue I have seen with oiled fabric filters, such as the K&N, is that the oil can contaminate the MAF sensor. Apply oil carefully and lightly to the fabric to prevent this.
Mike
MikeV has a good point - most people do not have a major problem running the K&N filters or systems - just the possiblity of over-oiling the filter or not waiting enough time to let the oil wick into the cotton guaze material.
If the MAF sensor cannot "burn" off this extra contamination - the sensor will report the correct air speed coming past it - usually resulting in poorer performance and or efficiency.
Otherwise - if you are careful with the oiling - you sould have to do any type of extra work.
Good Luck.
I've just switched to K&N as well... so thanks for highlighting the potential problems to me. I shall be careful with the oiling. 
What would you use to clean the MAF sensor if it were contaminated with filter oil, or would it need replacement?
You would need to replace it..
