I just recently moved from Colorado at 6000 ft above sea level to California at 5 ft above sea level with my Mazda 3s. Previously I was getting about 400 miles per tank and now I have been averaging 300 miles per tank. I know that at the lower elevation the car would require a little more fuel to run properly, but I can't imagine there would be a 25% loss in MPG's. Does anyone have any suggestions at what to do to get some of my MPG's back?

I have noticed that when the engine is warm, the idle is low onRPM's and causes the car to shutter a bit. I'm not sure adjusting that would solve my MPG issue, but it was just an observation.

 

In the first place, what are you driving... a 2.0 MTX, or a 2.3 ATX?
~300 is about normal for me (2.3L/MTX) andmy heavy foot too. The heavier air you are now in would allow fora greater charge of air/fuel, asyou should now (in effect) be able to pack more air per charge than before. More air= more fuel to keep the 14.7:1 ratio correct. The good news, in theory at least,is that you should be seeing more performance along w/the lower fuel mileage.

 

If you make a move which features that dramatic a change in elevation and conditions,a visit to a dealer is probably in order (and trust me, I don't like dealers, so that's a big thing for me to say). I know people who live in CO, they tune the cars there very uniquely so that they run well in altitude ... I'm thinking you may need to undo some of that now that you have relocated.

I agree with V1 (gasp!), you need to tell us more about specifically what you are driving.

 

I apologize in my haste to find out answers I forgot to provide more information. My 3s is the 2.3 MT 5dr.

I know that when these cars originally arrive in a higher elevation, they tend to run lean and in turn have to be richened up. I was not sure whether the car's computer did that automatically or if it had to be programmed. Now that I'm in the lower elevation I'mrunning richand I'm afraid that my engine is dumping too much fuel in. Again with older carbuerated cars I know the fuel mixture could be manually adjusted, but not sure what they do for the computer controlled models.

Thanks for the feedback so far.

 

Your welcome! That's just one of the things we do here.
And may I say that you have excellent automotive tastes too. ( ^ ^ ^ )

It's possible the ECU will adjust the mixture by itself, but I'm not sure it has that kind of range.
I'm also not sure if there's a special program for high altitudecars, but I would guess there is. You should be able to tell after a couple a' hundred miles, or when you get a CEL for a rich @ idle code. Your local parts store should be able to plug you in and tell if you have any codes on the OBDII system. The Auto Zone's here will do it for free!

Oh BTW, I like your screename too. For someone who's only 25 it's kinda' funny!!