Let's get this gas mileage thing down!

[Land Speeder]

8 mpg/city is about what I get. I'm told it's because I need an extensive tuneup and I believe my source since he loves 3FE's and has worked on my truck before. I specifically know that these things need to be done...
PCV Valve
Rotor
Timing check/adj
Run diagnostic codes
Vacuum test
Valve adjust
Compression test
clean the throttle body
Re set the throttle positioning sensor
clean the idle control solenoid
clean the cold start injector
clean the Air Mass meter

Man, listening to my own advice here, I can spend the money on the tune-up or pay the money at the pump over the next few months...
You might be in the same boat as me, needing a major tune-up.

 

[Rusty Phillips]

a couple of thoughts

get a vacuum gauge, put it on the dash and run the hose thru the firewall into the manifold

on acceleration, dont let the vacuums get to 0, (I try to keep em over 5 inches on acceleration unless I am about to be passed by a schoolbus and need some more giddyup) I have been trying to keep it over 10 inches when up to speed.

it really points out how heavy your right foot is

I tried to upload a pic of mine but it was over the max file size.



two - do as was suggested and measure your odometer vs. roadside mile markers

on a 60 mile trip I had traveled 1.05 times more miles than indicated on the odo

this was 285/75's (vs. 275/70)

the other side of that is that you need to drive slower (which will help mpg) because of the speedometer error.

anyone have good mpg data with their stock size tires and then with larger tires (no other changes)?

even after correcting for tire size my best mpg with 285's (high 14's) is less than my best with 275's (high 15's)
- unfortunately I really didnt get serious about checking mpg until I got the 285s installed so I have a lot fewer measurements from the smaller size.

I have been thinking about going back to the stock size when I wear these out.

 

[Digger276]

I have a 91 with 155,500 and it was getting pretty good mpg upper teens, but I installed the part-time 4wd kit in it to get that high, I also have borla exhaust, and still plan to high flow cats. It has now dropped, and now I am running rich, been working on it, I have rulled out the air flow meter, I am suspecting the fuel pressure regulator is on the fritz. All the readings on the o2 sensors were good.

Well, my 2 cents, good luck

 

[livelarg]

Thanks for all of the input,

All of the ideas are good.
As far as synthetic goes, I need to do that just to keep it running well. The tires do amake a difference, but with just 32's they are not big enoughto make that much of a difference. but the added weight and added rolling resistance may be costing 1 1/2 - 2 mpg when you add the added distance from tire size.

digger276: I am also running the part time 4wd. please keep me posted on the AFM and fuel pressure regulator.

Thanks
Kent

 

[parabola]

Calculated my first full tank on my new truck. 14.2 mpg city. Not as bad as I thought it would be but I'd love to get it in the 15's...

 

[livelarg]

My 91 with 31x10.50's consistently sees 9-10mpg for normal daily driving (10% interstate) and about 14mpg over 200 miles of interstate driving. 170k miles. Does that sound about consistant?

That is about exactly what I am getting.

 

[Hltoppr]

9-10 MPG city (which is why I'm on the motorcycle.... )
14-15 highway

1992, 200K miles

-H-

 

[wileetoyote]

11.5-12.5 mpg city/hwy driving (45mph/70mph avg)
10-11 mpg towing (3500lbs empty/ 4500lbs fully loaded avg)
13mpg long trips (light load on relatively flat highways)

'96 LC running 285's in/around Phx, AZ. tire pressure ~45psi. Full time 4wd and AC. Only use 87 octane. 90k miles on a bone stock engine. Did replace the cap/rotor/plugs (platinum)/ Fram Air filter about 5 months ago with no difference in mpg.

Looks like 90% of this forum is in this range with only the heavily modified, high mileage, and/or Part Time 4wd guys seeing a big difference.

Good luck

 

[Sorry Dog]

My '89 usually gets 13 and that's 2/3rds highway... but I drive 75-80 and have a lead foot in the city...and the dog's head is out the window.

The '91 I had that my friend now drives is basically 2mpg less with the same use. I attribute this to ARB bumper, front axle moving, less tuned, and 100k more miles.

BTW - When I changed my muffler to a dynomax after bashing the stock one I consistently gained at least 1 mpg. No other change whatsoever. It's gone back to normal over time but I'm due a few tune up issues like filters, plugs, wires, etc.

I dunno about the vacuum guage eggfoot method. Lately I'm thinking the motor would get the same or even better milage boosted so that it would shift way earlier. My city milage sucks because I try not let it shift before 2500 because it bogs so bad below 2000 in second. I think RPM's kill milage just as much or as throttle position.

 

[Zen Dude]

97 LX 6 hours of hiway driving only
17 MPG.
City driving, don't know " afraid to check"

 

[livelarg]

Gas just went up $.12 today, Man, I need to get my mileage down!

 

[Grouseman]

Just did my first check on my 1996 with 130K miles on it. It is stock for now. Got 15.69 miles per gallon combination of city and highway driving. I'm thinking I might get 17 or so on the road like Zen Dude.

Grouseman

 

[crushers]

want better fuel milage?
no brainer, stick a diesel in it...
cheers

 

[Rusty Phillips]

Just did my first check on my 1996 with 130K miles on it. It is stock for now. Got 15.69 miles per gallon combination of city and highway driving. I'm thinking I might get 17 or so on the road like Zen Dude.

Grouseman

do you have the stock 275/70-16's on it?

 

[Rusty Phillips]

I dunno about the vacuum guage eggfoot method. Lately I'm thinking the motor would get the same or even better milage boosted so that it would shift way earlier. My city milage sucks because I try not let it shift before 2500 because it bogs so bad below 2000 in second. I think RPM's kill milage just as much or as throttle position.

Id be really curious to see if we couldnt find some wire from the ECU to the fuel injectors that we can put a voltmeter on - get a lttle more immediate feedback on how quickly the gas is sucked out of the tank....

this past weekend I drove from Columbia to Clemson SC and back (for a cruiser get together and cookout) and managed 323 miles actual (305 odometer) round trip on 18.5 gals for 17.5 mpg

as I said before I'm normally in the high 14's, (probably 60/40 hwy city split) but this trip I wanted to try a couple things so I tried really hard not to drop vacuums below 10" at any time(had to floor it a time or two on the on-ramps). I sped up on the downhill sides (I got up to 80 mph in OD at 10" hg) and slowed down on the uphill sides (dropping out of OD if needed - a lot of 55 - 60 mph uphill runs @10"hg).

When all is said and done Im not sure it was worth the stress and whatnot to save 4.5 gallons of gas over the entire trip, and I really hate getting passed on the long uphill runs, but that's what I did, and it seemed to make a difference.

but as they say, your results may vary.....

one other thing regarding cruise control - I do not run the cruise control unless on relatively level stretches because what happens on the uphill runs it goes to WOT and vacuums drop to 0, (pouring gas into the engine trying to maintain speed) then as soon as you get over the top and start down the hill the throttle slams shut, and you start engine braking, pulling 20 to 25 inches of mercury on the intake side (which does nothing but try to slow you down)

 

[snowwolfwarrior]

The UK gallon is smaller than the US gallon 1 gallon equals 1.2 gallons in the USA
Just thought I would chuck that in for good measure...LOL

 

[Grouseman]

Rusty,

Yes stock size tires..

 

[aamiggia]

My 1997 LX consistantly gets 17 USmpg with 50/50 mixed driving and 18+ (very minor pluse) on the highway.

The best way to improve fuel economy is learn how to drive with fuel conservation in mind. The owner's manual has a section of tips for better driving habits. The best thing to remember is that you're driving a 2.5 Ton truck not a sports car.

want better fuel milage?
no brainer, stick a diesel in it...

BTW, a 1HD-T will get you about 23 USmpg which is only 5 ish mpg better than a late model 1FZ-FE. The 1HD-FT or 1HD-FTE is a different story. Neither of which will offset the install price, if that's all your concerned with.

 

[OGBeno]

Drive slow....like grandma.

You might get some bad looks or the but at least you know that you are conserving.

I generally go under the speed limit in town (so, if speed limit is 35, I go about 30).

I also generally drive 40/60 speeds: highway--about 55-65 miles per hour tops...cruise helps too.

There doesn't really seem to be a way to get the gas mileage up...that's the short end of the stick with these rigs...

I guess Diesel is one possible route...also a Honda as Stucky said...