count dorkula

hey cats . . .
just found your site - new member & new owner of 90 sr5 v6. my question relates to altitude and fuel economy - i live up at 7,800 feet in the rockies and wonder about mods to improve fuel economy up here in the rarified atmosphere. i had great luck rebuilding the carbs on my vintage bmw motorcycles with high altitude jets/needles etc . . . and can adjust mix in my carbureted 70 gmc 1/2 ton, but this is a very different critter obviously. anyone have any thoughts on adjusting oxygen sensors or computer information for elevation? are there different sensors based on elevation? mixture adjustments for the computer? (i do have "colortune" plug for adjusting mix - for the uninitiated, it's a sparkplug with a clear "window" for viewing the color of the ignition - adjusting mix until you get the right color of fire, blue or yellow - but the computer would need reprogramming, right?)

thanks in advance for any help. also any other links or sites you might suggest.

Dr. Zhivago

Sorry to be the one to break the news to you on this, but there really isn't much you can do to improve fuel economy on those engines. They get 12-15 mpg around town, with 12-13 mpg being the more common.

If your mileage is far worse than that, try setting the initial idle timing to 12* BTDC. A free-flow muffler might helps things a bit as well. You could also look into an ignition upgrade from say MSD.

Good Luck, but you really aren't going to find much that you can do. Welcome to the forums, by the way.

Dr. Z

aviator

hey count if you want to get better fuel economy try a K&N aif filter a cone filter kit (fipk?) will get you up to about 17MPG . I also ported the air meter (if you look in side the thing once you have it out you will see there is a lip there from the casting process with the meter completely out of the truck file down the bottom till the lip is gone . you must use a hand file it is aluminum and a grinder will melt it or take off too much metal too fast) reinstall everything and advance the timing on your engine about as far as you can (till it sounds wrong) then back off a quarter turn. I went from an average 15.5 mpg to 17.4 mpg and when I run a can of octane boost with the regular in the tank i get 18.9 mpg. you can also put on an aftermarket exhaust. I'm having a custom manifold back set up with a free flow cat installed. if you decide to go cat back ie borla have a free flow cat put on as well. my mechanics clients who have this done are reporting 2-4mpg over stock improvement and it sounds better too :-) a stock K&N rplacement filter should give you at least a 1-2 mpg improvement in any case I 've owned 87 yj 87 toyota hilux and saw improvements in that range with more power as well. hope this helps.

aviator

opps forgot to mention those milages I quoted are for two wheel drive opereation in four wheel drive i went from 12 mpg to 14 mpg this winter but then around town we only use 4wd when they have'nt plowed the roads yet or to get that good parking spot on top of the snow pile at the multi-plex right:-)? chees