Thank you bls. It is just so things I didn't know while testing and fiddling with my other Nissan fell in place with my Micra. I have learned with my other Nissan in the hard way (keep on driving with issues that do not influence reliabillity like a worn MAF, rinse and repeat with second hand parts of unknown state, getting of the couch and fire up Datascan again), what helps fuel economy. This is because I learned quickly better fuel economy on an old car means more low end response and quicker 0 - 60 times which you can record with Datascan in a hundred percent correct reading.
It is not hard to chew away a full second on Nissans figures for a 0 to 60.
Also, low end power means you don't have to go to high rpms to keep up with a normal traffic pace and that gives better fuel economy. For a MAF one is worried about, some exhaust sniffing which is the not recommended way can help. I did work on moped all my life though and that knowledge is quite valuable on exhaust fumes. I'm sure though that a regular inspection on the spark plugs works just as good after each modification, repair or replacement of a crucial part like a MAF.
I admit I still didn't buy a new MAF. For my other Nissan, if I can be sure it will solve my driveabillity issues in full or just half of it I would buy a several hundreds Hitachi. For my engine and my country I can buy a *new* MAF for fifteen :/ But in the end it all depends on what wire is soldered there and yes, MAF oem's can be a total fail. If they decided to use a lower grade or just the wrong wire, your driveabillity might change completely. If you are not that keen on fuel economy like I do, a second hand original MAF with low mileage is a good way to turn your driveabillity of your car back to fun again.
I will order a Ali Express MAF and a cheap MAF in the fifteen range and compare with the MAF I have I know is both with lambda responsible for the heavy fumes my Micra is throwing out. Heavy fumes at cold start are not a technical problem, but fuel economy might suffer a bit. Fuming with a fully warmed engine (if your radiator fan starts and stops is the measuring point), will give bad fuel economy.
But as I wrote before, thermostat, lambda, MAF and rotor and cap, if you want a happy Micra, start looking there. You can measure a MAF without Datascan though. A lambda replacement can be a pain and a thermostat replacement, if you are a handy person, people that have done it can talk you trough. But a lambda or MAF replacement on a good working car can make sense. Replacing a thermostat without being sure how good or bad your current thermostat makes no sense, but I told you how to make sure.