Originally Posted by Javi22RE
Good to get a thread like this going with someone willing to help others out. I'm still searching for my crappy gas mileage fix. New plugs, wires, air filter
, fuel filter, timing is set at factory specs, maf sensor (brain fart on the name for our set up, I know its not maf) works well, no vacuum leaks, brake booster seems to be ok, idle is correct, tps was just replaced, not sure what else to check anymore.
But it could be that this thing has different gearing than stock as it is way too peppy in 1, 2, 3, and 4 with 33s on the street. Swapped in a diff from a donor truck awhile ago, didn't check the gearing.
From my old trucks, every single one with tires bigger than 31x10.5 got terrible MPG for being a 4cyl
gearing def can be a part, my truck with 4.88 and 35x15.50, welded diffs and lockouts on the front only got 11-12 mpg.
My 85 with 32x10.5 in all proper specs and driving nicely usually only got around 16 mpg average but was a dog.
My Dads 85 with 31x10.5 and 4 inch lift gets about 21 mpg highway, 4.30 gears but he drives extremely nice. Before the lift he averaged about 22-23 with the same size tires
My 81, with 31x11.5 swampers gets about on the highway with 4.37 gears and 17-18 with 31x10.5 street tires.
Making sure the AFM and everything is in spec is usually the first step, i have seen more than a few 22r and 22re trucks that have been 1 tooth off on the timing chain with everything else in spec and they usually know its off with bad MPG
A worn chain will also cause you to get worse MPG even if its not worn to the point of rubbing your timing cover.
With the new TPS did you adjust it with a multimeter after installing it?