hey guys!! loooong time since i have posted had a few questions on how to get better mileage. all mods are in my sig. the mileage im getting right now varies between 10mpg-13mpg and thats the best i can get. i drive like and old man most of the time. i have 3.07 gears and a three speed auto no overdrive, i dynoed almost 500rwhp. im not sure what the deal is. i have 435 injectors and the timing is at 16.5, should i get a better set of injectors, change the timing??? any ideas. thanks for any help you guys might have


jason

 

whats your rpms when your cruising?

brett

 

i cruise 2000rpms at 60mph and about 2400 at 75mph, also on my way to Idaho a couple months ago i was getting like 18-20mpg at 70mph for about half my tank but haven't gotten that ever again, and on my trip to montana i drove 70-75 most the way and got from 12mpg to 15mpg a tank, even when i did 60mph for an entire tank of fuel i only got 13ish mpg so i dont know what the problem is


jason

 

Winter fuel is lowering your mileage.

 

Well if you have no overdrive then your fuel mileage will drop significantly if you're going 70-75 mph. You sure you got 3.07 gears?

 

All 1st gen 3spd autos should have 3.07s

 

Ohhh... I read 1999 for some reason.

 

i dont think winter fuel would account for a 7 mpg drop in milage. something else is going on...

brett

 

Your lift and larger tires will really hurt your fuel mileage but it still sounds too low to me.

Does your engine sound normal? Is there any extra smoke? Are your filters up to date(air & fuel)?

Have you checked to see whether your brakes are dragging? It is probably worth jacking up each end and seeing whether everything spins freely. Also, it is worth seeing what the temperature of your hubs are after driving for a while to make sure that you don't have a bad bearing or something.

 

fuel shouldnt make that big a difference, and the injectors you got shouldnt make that big a difference, the rpms that you're cruising at are fine and even shouldnt make that big a difference, anything with an extra load on the engine will cause low fuel mileage. for ex. in the summer for hay hauling i use a fan clutch that is froze up and will turn all the time well i left it on for a week and mileage was goin from 25 to 18. then when the ps pump was going out my mileage droped the same amount.

 

well i changed all my filters a week ago. my a/c clutch came apart this summer so i got the non a/c serpitine belt so i have even less drag on my motor. it does smoke/haze at low speeds around town, but only until it gets up to speed, i think im going to check my timing, since i want to bump it a little more, hopefully that will help, any ideas on some different injectors 125-150hp range but will give me better mileage?? thanks for the help


jason

 

cant go wrong with the DDP4's, i've seen them with no haze and about the same smoke as 215's
oh yeah just noticed you got lazer cuts and a 64/71/14 that definatly isnt helping. before you get bigger sticks i would try some 181's but that still inst goin to help much with the lag of the 71mm wheel

 

ya the laser cuts can dump some fuel, but made no actual mileage difference when i swapped them out for my stock dvs. i do plan on twins, 62/13ss over an s400, but who knows when ill build those, maybe if i get the 62/13ss and run it as a single for now, would that improve mileage??? who nows im out of ideas


jason

 

the the are you gonna get the 71mm wheel? if so, that is still gonna have some lag, would even more laggy in a twin setup.

 

Just an idea but are you taking into account the larger tire size? Is your speedo corrected for the 33s?