M5 Gains 139hp After Removing MAF Sensors?
Faulty MAF sensors are a common cause of underperforming BMWs, but an “Alpha N” tune can bring your car back.
Imagine this. You’ve just bought a fun weekend car. You envision all the windows-down road trips through scenic mountain passes you will enjoy. You hop in to see what she’s got, and it’s an underwhelming “Meh.” But, if you could remove a simple part, say MAF sensors, and see a performance increase, wouldn’t you?
In a recent video from Legit Street Cars, host Alex Palmeri introduces us to a friend who has lived out this frustrating experience. But, a fortunate turn of events saw this proud owner receive a 139hp gain thanks to a simple diagnosis and tune!
Greg, whose surname is unmentioned, owns a 2000 BMW E39 M5. Even for a 19-year-old car, Greg’s Bimmer was sluggish. It never quite lived up to its potential. Over his three years of ownership and several repairs, Greg simply grew to accept this as an unfortunate reality.
But, his luck would turn upon meeting up with Palmeri for a dyno battle. Originally, Palmeri wanted to see how much power his vehicle had lost over its 400k miles. But what happened next shocked them both.
The Diagnosis
Upon its first dyno run, Fluid Motor Union Owner and dyno expert OJ Lopez knew something wasn’t right. “So, right off the bat, it sounded weak,” says Lopez. “The numbers that we’re seeing; extremely low.” The M5 maxed out at 207hp. Ouch.
Well, that’s sort of good news. Lopez goes on to explain that his guess would be faulty (Mass Air Flow) MAF sensors. Without a check engine light, they’ve likely become dirty or aged in such a way as not to trigger the system.
Furthermore, Lopez explains that, by disconnecting the MAF sensors, he can get a better idea of whether or not this is indeed the problem. Essentially, by disconnecting them he can force the car into a background running mode. By doing this, the M5’s computer will utilize its rpm, throttle position, and known displacement to determine the air-fuel ratio.
“So there’s stuff in the background that don’t make it run 100% right,” says Lopez. “But when people talk about Alpha N tunes, basically what you’re doing is you’re taking that table and you’re eliminating the faults associated with it so that it can run there. And then tightening everything up.”
After disconnecting the MAF sensors, the team goes for dyno run #2. Instantly the car sees a 60hp improvement. That’s a huge jump on its own, but Lopez knew there was still more to be had.
For the 3rd run, the crew made some adjustments to the ECU by clearing the adaptations. The M5 sees another 40hp gain!
The Alpha N Tune
“So BMW does a great job from the factory so that that car will run in case you do have a fault,” explains Lopex. “But, that being said, in order to keep this thing road-worthy you need to have a tune in there to compensate for that.”
Wanting to see how much more they can squeeze out of the M5, they decide to throw in an Alpha N Performance Tune. After a few tweaks, the tune pushes the car to an astounding 346hp. Altogether, that’s a 139hp increase! That’s equivalent to buying a new car. All from disconnecting the MAF sensors and tuning the car.
Now, thanks to the experts at Fluid Motor Union, Greg has a minty fresh E39 M5 that’s actually fast. What a thrill! And remember kids, check your MAF sensors!
Photos: Legit Street Cars