why does my 2002 nissan sentra xe 1.8 have no power? it threw a p0102 code and a p1102 code both saying MAF sensor. i changed the MAF sensor and now it runs even worse than before, only revs to 2500

Did the mechanic erase the cpu memory? Refrase: Did the mechanic hooked the car on the computer after replacement?

You need to clear the codes, if it hasn't been done after the installation of the new MAF sensor. If this doesn't solve your problem, you may have a faulty MAF sensor or connection. You will then want to make sure your plug is well cleaned and the wires, not damaged. Some MAF sensors are reputed to be fragile, handle with care. Good luck with the repair!

the computer was cleared after the MAF was replaced. i was thinking the new MAF is bad. it just looked like someone had superglued it together, but also the plug going to the MAF looked a little worn where it get wrapped into the wire harness just at the plug end. i dont know what else to do or check.

You will need to test your MAF sensor to see if it is functioning properly. I never tried it but this tutorial seems to explain it well: http://easyautodiagnostics.com/nissan_maf_sentra_1.8L/sentra_maf_test_1.php Come back after with your results to share it with others :) good luck!