My 03 is throwing a p0102 code for the maf . It runs perfectly fine just throws a code , I swapped it for another maf I grabbed from a junyard down the street for 10$ just to see what would Happen and it makes the entire car shake like a missfire but doesn’t throw a code at all , then I put the old one back in runs perfect but the code comes back up. Any suggestions? I tried cleaning both with maf cleaner no diffrence

 

The engine ECU has "adapted" to the original MAF, sometimes you can simply swap it out if it isn't bad enough that when you swap it the config is so close nothing changes, or sometimes it will barely run at all as it's now reading something entirely different. You can reset the adaptive settings with a good enough scantool like a Hawkeye, Lynx, AutoLogic, T4, or a SnapOn tool. Or you can sometimes get away with tricking the ECU into relearning the config, by leaving the crappy running one in it and taking a drive getting the RPM's above say 2K for a short trip. It will sometimes reset the values, but other times it won't. Or the MAF you got used was damaged or dirty from the parts car you got it from.