I remember 10 years ago when I moved to Denver one ofthe dealerships said that I needed to replace my mass air flow sensor on my 85 Jeep, as well as any car I brought wih me from lower altitudes. Was that true? Is it still true?

I mean, I had a 93 Nissan P-finder that I never changed the MAS and it ran just fine for 7 years. It did have a pretty dark tailpipe like it was running rich, but that could have been from the oil leak it had too

Do today's cars/trucks need a MAS change when going to altitude, or is it one of those dealer tricks?

 

An 85 jeep most likely didnt have mass air. Most jeeps swapped from carbs to FI in 86. Mustangs didn't get mass air until 1989, and I don't know specifically when the trucks got it, but I read something that said like somewhere between 93-95.

 

My old 93 'xpoder was a rental that had come from Denver. It had a sticker under the hood that said it had a special high altitude version of the PCM code flashed in it.

Most PCM calibrations have sufficient capability to self-adjust to high altitude operation. If in doubt, check with a local dealership to see if one is recommended for your specifc vehicle.

Steve

 

The BARO reading from the mass air will update after a WOT acceleration nowadays anyway.

 

Right - it updates during key-on (before start) or during WOT.