I would like to tune my 1990 Chevy k2500 for better fuel economy and am new tuning so I have little to no idea what I am doing and nee some helping find tools and resources.

 

They're generally programmed to shoot for stoichiometric air fuel ratio. So around town I'm not sure there's much improvement to be had, other than going easy on the throttle.

Where there could be some improvement is on the highway. If the ECM has highway mode like my 7730 ECM does, you can program in a lean AFR, like 16:1 for light throttle cruise. I picked up a few mpg by activating that mode. It's not activated by GM from the factory. It automatically disengages when you try to acclerate.

However, I'd recommend getting a WB O2 to measure the actual AFR. You don't want to accidentally go too lean. For example I program in 15.5:1 to get 16 to 16.25:1. Often times there is a significant difference between the commanded AFR and the actual AFR.

 

You might pickup a few MPG on the highway as noted, but it's probably not going to justify the investment in equipment and the learning curve to do it. I wouldn't start out tuning by trying to maximize fuel economy - playing with lean mixtures can be trouble for new tuners. You might melt a piston, burn a valve, etc. Better to learn how to make power and richen things up before you start playing with lean mixtures.

Also you aren't likely to stand to gain much. It's a 3/4 ton truck with a V8..... I mean seriously. That's a work tool not a commuting appliance. Fuel cost shouldn't really matter much. At least not the amount you might be able to get for the effort on that rig.

GD

 

GM did enable highway mode in some bins but not all. I know the 305's in 89 it was enabled. FWIW.

 

Interesting info... thanks for the clarification. My guess is they were worried about NOx emissions or something. ..