Gas mileage improvements?

[srmitchell]

The EPA estimates dont seem to factor the CA gas, let alone the garbage gas we get in humboldt county. I get about 3 mpg less than in the bay area.

Highest gas prices in america!

 

[cruiser54]

:laugh:

The EPA estimates dont seem to factor the CA gas, let alone the garbage gas we get in humboldt county. I get about 3 mpg less than in the bay area.

Highest gas prices in america!

Doesn't the marijuana growing subsidize the gas prices? :eyes:

I attended Humboldt State in the early 70s. :laugh:

 

[clean96XJ]

If I remember correctly, Eureka is really foggy and has some serious hills.
Twistly roads too! All MPG killers.


High Humidity can negatively affect your gas mileage.
-Run AC to defrost the windows.
-Engine takes longer to warm up. etc. etc..


And those hills and twists!

"It's all relative!"

 

[srmitchell]

Makes sense to me.

 

[bigalpha]

This is for the 1995 year. (LINK)

2WD, 6 cyl, 4.0 L, Automatic 4-spd, Regular 14 19
4WD, 6 cyl, 4.0 L, Automatic 4-spd, Regular 13 18

​

This is for the 1988 year: (LINK)

2WD, 6 cyl, 4.0 L, Automatic 4-spd, Regular1520

4WD, 6 cyl, 4.0 L, Automatic 4-spd, Regular1520

As you can see, there is no difference in the estimates for the 1988 year for 4WD vs. 2WD. There is a 1mpg difference in the 1995 model year.

 

[cruiser54]

Thanks bigalpha.

 

[ONDAROX]

My MSD ignition helped alot

 

[DieselSJ]

My MSD ignition helped alot

Define "a lot". Also, what other things did you change when the MSD was installed - cap, plugs, wires...?

 

[CharlesS]

My 1998 XJ has been using the MSD 6a and Blaster coil since 2000 and while it does provide a hotter spark (required a larger plug gap of .045), smoother idle and better throttle response; I didn't notice much in the way of a mpg improvement.
MSD does recommend NOT using platinum and similar sparkplugs.

 

[kidarkitect]

Oh yeah, another thing. I eliminated the CAD on my 90 Comanche and fuel mileage stayed the same.That's good enough evidence for me.

thats good to know.

who knows maybe when the time comes i'll do hubs anyway, and report back. science is all about hypothesis and proving or disproving them. but learning from others can save wasted time. thanks!

for me this is part of the fun of tuning/building/modifying vehicles. iow my goal for my jeep is to make a capable overlander that doesn't waste anything unecessary. and maybe one day it'll be a jeepspeedish prerunner but at that point it wont matter anymore.

i think my next attack will be some new injectors but its going to be a little while. after reading up on this thread, i wonder if i may be losing fuel after shutoff. of course i have a renix so a longer crank time is to be expected from what i've heard/read.

speaking of your comanche, i saw on mythbusters after someone brought them up in here. that the myth of driving w/ your tailgate down is better is wrong. interesting to me bcuz i used to have a f150 that i put a lot of miles on. two actually but one was a snowmobile and snowboard drop-in hauler exclusively so i never cared much in that one.

 

[kidarkitect]

This is for the 1995 year. (LINK)

2WD, 6 cyl, 4.0 L, Automatic 4-spd, Regular 14 19
4WD, 6 cyl, 4.0 L, Automatic 4-spd, Regular 13 18

​

This is for the 1988 year: (LINK)

2WD, 6 cyl, 4.0 L, Automatic 4-spd, Regular1520

4WD, 6 cyl, 4.0 L, Automatic 4-spd, Regular1520

As you can see, there is no difference in the estimates for the 1988 year for 4WD vs. 2WD. There is a 1mpg difference in the 1995 model year.

Good base, thanks! See I get better than that on both fronts. (89 4x4 5sp cad 3.55r&p and 30") in the city 16 is the low end which happens when i've been stomping on it. highway average is about 23-25 and i've been as high as 27 on multiple consecutive tanks. google checked because i didn't believe it myself. this is also with camping gear, and a 80# front bumper. so it makes me wonder why.

other stuff i've done:
reg maintenance junk
K&N drop in
manifold back exhaust - 2.25 dp 2.5" cat and cat back w/magnaflow

i don't drive like a grandma either. :dunno:

the only time i fall that low is pulling a small trailer around the city.
(1989)
Jeep Cherokee/Wagoneer 4WD
6 cyl, 4.0 L, Manual 5-spd, Regular 15 20
$2276
10.80 NA

 

[kidarkitect]

Wait- this is why i don't put much stock in epa numbers look at 88 v 89 my model

listed 89 above.

1988
Jeep Cherokee/Wagoneer 4WD
6 cyl, 4.0 L, Manual 5-spd, Regular 16 22
$2152
10.20 NA

thats a 1mpg diff on city and 2 mpg diff on highway. not much changed between those two years, trans halfway through but gearing is similar enough that there shouldn't be a difference right?

 

[ONDAROX]

I gained about 2mpg when I did my MSD swap. Of course there were some other variables that could have been a factor. I did replace the spark plugs, wires, coil, and ignition all at the same time. anyway... I'm currently getting about 18 mpg with 8" of lift, 39.5" Iroks, and 4.88 gears. I'm pleased.

 

[yossarian19]

My MSD ignition helped alot

Vs an old, tired out stock ignition? Or vs a new-ish factory unit?
In a lot of cases, after market parts only seem to enhance performance - when in reality they are only restoring the lost performance due to the age of an OEM part.

 

[Dobbs]

I know on older car I had growing up with 75,000 to 100,000 on them the first thing I did was the timing chain and gears. made an unbleavable diffance in the way they ran havent looked at the way the 4.0 is set up but would bet changing it would help a lot setting the valve timing back to where it was factory.Giving more power and milage .Replacing the coil ,wires and any thing elese that could lose some of it ump will help for sure.

 

[Zuul99]

Gas mileage improvements dont work. there are so many variables that factor into fuel eco that gaining 1 mpg is nothing. I've gotten 22mpg driving in the city in 110 degree day in phoenix next week i got 15mpg and my driving style didnt change

 

[srmitchell]

I know on older car I had growing up with 75,000 to 100,000 on them the first thing I did was the timing chain and gears. made an unbleavable diffance in the way they ran havent looked at the way the 4.0 is set up but would bet changing it would help a lot setting the valve timing back to where it was factory.Giving more power and milage .Replacing the coil ,wires and any thing elese that could lose some of it ump will help for sure.

Call me stupid, but isnt the 4.0 non adjustable?

 

[cruiser54]

Call me stupid, but isnt the 4.0 non adjustable?

Stock cam and crank gears are non adjustable.

 

[Talyn]

They are non adjustable, but the chain will stretch with age. Using an adjustable timing set on a stretched chain is just a bandaid. Replacement timing set is the best bet.