Please pardon my dumb questions but I really hope someone can shed light on this subject.

How does it know I have a good MAF on if it's unplugged? This is what I find confusing, lets say my MAF is bad, If I unplug it the car should technically run like crap anyways since there's no more MAF readings? I don't understand that if I have a good MAF on and unplug it the car should run like crap. If I unplug it, the car runs well and my readings for long term fuel trims go back down. To me, information about the MAF is very confusing, My car runs well with the MAF plugged and unplugged, when the MAF is plugged my idle and redline readings are within spec but I run lean. With the car running if you unplug the maf and it stays running then its not working.I've read that as well. These are simple tests you can do to help diagnose a bad MAF without having to take the car to the dealer or anyone else.With the car running if you unplug the maf the car is suppose to shut off that means the maf is good and its working. If it holds fine while cruising and climbing a hill on the highway, the MAF is probably OK. In this case you'll notice the set speed slowly dropping off and you'll be wanting to nudge the set speed upward. How well does the car hold speed on the highway with cruise control on while climbing a hill? One early sign of a dying MAF is the cruise control won't be able to hold the car at the set cruise speed while climbing the hill. A good MAF will allow the engine to rev to 5100 RPM easily.

With a dead or very sick MAF, the engine won't be able to reach the RPM limiter at 5100 RPM. If power and performance goes away with the MAF unplugged.MAF OK.Īnother test you can do is put the car in neutral and slowly press the go-pedal to the floor. If power and performance improves with the MAF unplugged.BAD MAF.replace. The ECU will automatically use a default value for MAF readings. It may set a Check Engine Light (CEL) code due to it being unplugged but don't worry about it. Try unplugging the MAF (not 'MAS' BTW) and drive around with it unplugged and see if performance improves at all.

Audi a4 mass air flow sensor problems