I’m in the middle of replacing my former, mild, BMW Performance ECU flash with MHD Stage 2+,which I have all the mods to support. Watching that percentage slowly count up while your fuel pump runs continuously is kinda like “OMG OMG OMG PLEASE WORK AND DON’T FRY MY ECU PLEASE THANK YOU CAR LORDS!”

Also the dash lights up like the proverbial Christmas tree.

Thankfully, this isn’t my first experience with flashing my ECU so I somewhat know what to expect. I experienced the same fuel pump running and warning lights when my coding guy did the BMW Performance flash.

I’ve got my car hooked up to a beefy 15 amp battery charger so running the fuel pump doesn’t kill the battery. I also have my tablet with me since the device flashing the ECU needs to be in airplane mode and you can’t leave the flasher app. Hence the grainy, noisy pictures from the crappy tablet camera.


MHD is a well-known app but I can’t help but feel nervous using my phone to rewrite my car’s ECU with cheap K+DCAN and USB OTG cables I got on Amazon.

That said, hey, I’m now up to 32% and I haven’t gotten any error codes yet. Fingers crossed!


(Yes, I’m wearing tights, I’m going to have a quick shakedown drive on my way to the gym.)

UPDATE: I’ve resorted to passing the time while the counter slowly marches upward by watching this video of super cute baby sloths.

Also when it hit 88% the fuel pump paused for a bit, the iDrive screen turned off, and the seatbelt butlers popped in and out, which freaked me out for a sec. But the fuel pump restarted, the iDrive screen came back on, and the counter is still going up! Phew!


UPDATE 2: It worked! I did a few 2nd gear WOT pulls up some on ramps and hoo boy that’s a noticeable improvement over the BMW Performance tune. Like, rolling on to WOT in 2nd is now enough g-force to trigger the seatbelt pre-tensioners. Fun stuff.