MPG Revelation

[maybe_a_80...]

Thought this might raise some eyebrows...

my '96 FZJ80, which just came into my posession, had original spark plug wires and 56,000 miles on the spark plugs (at least), original distributor cap and rotor. air filter was an aftermarket replacement. i don't think the transfer case, transmission, or differential fluids have ever been changed and the front axle needs a rebuild...the truck has 106,700 miles on it.

i got 13.6 mpg off the first tank.

to me, it is amazing that i got that good mileage off a vehicle that has has very little PM over it's life....given the truck is carrying no gear and the tires are LTX M/Ss 275/70R16. this speaks volumes about the quality of these vehicles.

tonight i replaced the spark plug wires, spark plugs, distributor cap, rotor and air filter with OEM parts (thanks cdan!)...i'll repost change in mileage once i get through another tank (should be a week or more).

i plan to have all the fluids changed and rebuild the front axle in the next couple weeks...will be interested to see what happens to fuel consumption when everything is in tiptop working order...

 

[IdahoDoug]

Heh, don't hold your breath. Modern engines can run just fine for that interval without serious MPG degradation. As long as the air filter's not plugged they'll keep compensating and that aftermarket filter may have been HELPING you with poor filtration and thus low resistance. Drop a nice quality Toyota OEM filter in there and you'll be getting quality filtration.

DougM

 

[reffug]

1-2 mpg improvement at best would be my guess.

 

[maybe_a_80...]

Heh, don't hold your breath. Modern engines can run just fine for that interval without serious MPG degradation. As long as the air filter's not plugged they'll keep compensating and that aftermarket filter may have been HELPING you with poor filtration and thus low resistance. Drop a nice quality Toyota OEM filter in there and you'll be getting quality filtration.

DougM

It still amazes me...such old parts and still "good" mileage for a 80.

i replaced the air filter with an OEM one last night.

 

[maybe_a_80...]

MPG Update

so, just drove 325 miles yesterday. Since my last update I had Mark Miller Toyota spend an hour tuning up my engine, like they would in a tune-up. As mentioned before, I recently replaced the wire, plugs, rotor, air filter and cap with new OEM parts.

I am now up from 13.4mpg to 15.6mpg!

 

[alaskacruiser]

maybe- it sounds like you did the tune-up yourself! What exactly did Mark Miller Toyota do with your truck for an hour?

 

[rhyary]

When testing for MPG you got to make sure you are measuring round trip. Goint one way and checking for MPG is not a good indication for true MPG

 

[maybe_a_80...]

maybe- it sounds like you did the tune-up yourself! What exactly did Mark Miller Toyota do with your truck for an hour?

i'll get back to you when i get home - yes i did alot of the tune-up myself but the engine was still not idling or running as smooth as i thought possible, so i asked them to adjust the engine...it only took them half an hour and it is noticeably better. i'll repost with exactly what they did when i am home next week.

 

[maybe_a_80...]

When testing for MPG you got to make sure you are measuring round trip. Goint one way and checking for MPG is not a good indication for true MPG

Salt Lake City, Utah to Steamboat Springs, Colorado on US40 was 15.6mpg.

It will be interesting to see the round trip, which will include Steamboat to Winter Park to Summit County to Denver and then back to Salt Lake. I'll repost when I get home for sure.

 

[gnx7]

what is your speed and was it windy? A near stock rig should get better than that

 

[maybe_a_80...]

what is your speed and was it windy? A near stock rig should get better than that

I was driving over 70mph the whole way. If you haven't driven US40 from Park City to Steamboat Springs, it is extremely hilly, so can wreak havoc on gas mileage.

My mileage keeps getting better - the last tank I averaged 16.7mpg, again at 65+mph the whole time!

 

[SnapsEighty]

I'm curious as to what they did to make it run smoother. Clean the TB? Couldnt have did the injectors in half an hour. Well maybe if it was a on the vehicle machine which hooks up to the fuel system. What did they charge you for that half hour?

 

[Blue Bomber]

Have you verified your odometer/speedometer vs. GPS? That is really great MPG.

 

[maybe_a_80...]

I'm curious as to what they did to make it run smoother. Clean the TB? Couldnt have did the injectors in half an hour. Well maybe if it was a on the vehicle machine which hooks up to the fuel system. What did they charge you for that half hour?

...still not home to check exactly what they wrote down, but will post when I get home Wednesday. They did not clean the fuel injectors, which I plan to have cleaned when I return to the States in October.

The shop charge was about $50 for the engine work, IIRC.

 

[maybe_a_80...]

Have you verified your odometer/speedometer vs. GPS? That is really great MPG.

Unfortunately I have not verified with GPS...I don't have that hardware.

 

[smileyboy]

Did a trip to Pubelo this weekend from Denver. Drove 269 miles. before the lift, tune up and larger tires. i was at 12.66 mpg. After lift, tires, new spark plugs, new cat and new magna flow exhaust, I'm at 14.34 mpg. I need to do a new cap and rotor and wires and i'll report back. I am hoping for 15-16 mpg and I'd be happy.

 

[Chevinater77]

wouldnt the larger tires warrant a false reading in higher mpg?

 

[smileyboy]

My speedo was adjusted.

 

[maybe_a_80...]

OK. Last information post from me on this thread cause it's beat.

My round trip gas mileage for the trip was:

1,656.6 miles driven.

103 gallons gas used.

= 16.08 mpg.

I'm impressed.

The work I had done at the dealer after replacing all that stuff in the driveway was simple stuff I just don't know how to do - Mark Miller Toyota adjusted the engine settings and it made a difference for sure - the engine idles smoother and clearly runs better. Worth the $50 to me, just to have the engine idle smoother.

I guess my conclusion from all of this is that if your 80 is hogging gas, do all the basic tune-up stuff you can think of and you'll probably get at least a couple miles better gas mileage.

The next thing I am going to do to make everything run smoohter/more efficient are:

• change diff fluid front and rear
• rebuild front axle (questionable as a benefit, but new wheel bearings can't hurt)
• engine rail cleaning service at the dealer
• new fuel filter
• adjust throttle body to get transmission operating tighter (not shifting as well as I think it can)

I'm not trying to go overboard, it just happens that alot of the PM I am doing seems to be positively affecting mgp.

Over and out.

 

[sundaypunch]

wouldnt the larger tires warrant a false reading in higher mpg?

Larger tires give you a false reading but they make your mileage look worse than it actually is. They also make your speedo read slower than actual.