39 MPG, hope I can repeat

General information about the first-generation Nissan Maxima in the US. What was the Datsun 810 became the luxury leader Maxima in the US in 1981.

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odie
Posts: 114
Joined: 13 years ago
Location: CC, TX

39 MPG, hope I can repeat

#1

Post by odie » 12 years ago

my last leg of my trip I pulled 39 MPG. New Orleans to Meridian MS, kinda hilly too, doing 70.

I'm surprized since I usuall get 28-29 commuting to work and only got 33 from South Texas to New Orleans in the flats.

Maybe I had a great tail wind, lol. Or just a fluke.
1996 VW Passat B4V TDI diesel...main ride
1983 Maxima LD28..sold
1984 Isuzu P'up diesel 4x4..sold
1981 Rabbit diesel - sold
1984 MB 190 diesel - for sale...sold
1987 MB 300TDT diesel...sold
1983 Holiday Rambler 6.2 diesel Banks turbo...sold
1983 Dodge Ram D50 2.3 TD diesel for sale
gas stuff-Jeep, Lebaron, Porsche, Harley

rlaggren
Posts: 541
Joined: 13 years ago
Location: San Francisco

#2

Post by rlaggren » 12 years ago

Tail wind _can_ make that kind of difference. But maybe you just refrained from pumping the right pedal. <g>

Rufus
82 Maxima wagon

odie
Posts: 114
Joined: 13 years ago
Location: CC, TX

#3

Post by odie » 12 years ago

well, there really was not any wind. I had the cruise on. it's just a bit of a shock. does anyone get 39 in these cars? the real trick is to repeat it on my drive back, and over & over again.
1996 VW Passat B4V TDI diesel...main ride
1983 Maxima LD28..sold
1984 Isuzu P'up diesel 4x4..sold
1981 Rabbit diesel - sold
1984 MB 190 diesel - for sale...sold
1987 MB 300TDT diesel...sold
1983 Holiday Rambler 6.2 diesel Banks turbo...sold
1983 Dodge Ram D50 2.3 TD diesel for sale
gas stuff-Jeep, Lebaron, Porsche, Harley

rlaggren
Posts: 541
Joined: 13 years ago
Location: San Francisco

#4

Post by rlaggren » 12 years ago

I'll bump this thread to add info related to fuel economy.

I recently installed new large rear tires 215/75R14. There were handling differences (slower acceleration, more wiggle from the rear when changing lanes or on grooves) and some increase in fuel mileage.

Tire data from the Yokohama and the Bridgestone site mostly agrees which each other (the static radius is the actual radius with the tire inflated properly and loaded by the car):

185/70 has a static tire radius of 10.9"
215/75 " 12.4"

Delta is 1.5" and it's 13.76% over the stock radius - kinda more than my guess of 8% before I got the figures. This also agrees with the measurements I made on the tire while parked.

In the last 3 tanks, my corrected MPG is about 28.3 in daily driving around (not so much in) San Francisco. Two good hill climbs (guessing ~700' vertical) to and from Pacifica 4 or 5 times a week, then about 70/30 hiway/city. With the stock tires I got about 27 MPG.

This is OK but not a no-brainer unless you live in the flat lands. The gear ratios make it hard to find a good spot to climb the hill and the 35mph set that many of the timed traffic lights around here use means that I can't reach lock-up while traveling these streets (I could usually get it locked at 36mph previously). The car can make the hill in 3rd and locked but it drifts slowly down to 38-40 mph (indicated) over a period of a 90 secs or so. 2nd will bring the speed up but with excessive (for economy) revs and no lock-up.

There are a couple things that would make this better:

1) Modify the TC lock-up so it could be controlled by the driver; also lower the base lock-up to an indicated 32 mph. If the driver could enable and disable lock-up in both 2nd and 3rd, then hill climbing would work better. Probably have to monitor the tranny temps if running open in 3rd.

But that looks like real high-up pie. The FSM doesn't have much detail info on where the hydraulic circuits for the tranny are located so I don't know if theres a way to jigger the TC control by inserting a solenoid valve and I'm not inclined to scrunch around under there for the forseeable future. Probably be quite a diddly project anyway. <g>

2) Raise engine power. I don't think my injectors have ever been serviced so that might be an easy try. I don't see any smoke when I'm going up the hill so possible the fuel delivery could be increased (very) slightly; I'll have somebody tail me up the hill to confirm this. Don't know how bad that would hurt economy. When I get ambitious I'll tee a vacuum gauge somewhere into the intake manifold and see if it's throttled at all; if so open it up somehow. Turbo would be a perfect fix but that's not in sight at this time.

Cheers, Rufus
82 Maxima wagon

odie
Posts: 114
Joined: 13 years ago
Location: CC, TX

#5

Post by odie » 12 years ago

I could never repeat it. I think it was a one time fluke or something. But thats what the math showed. Filled up, drove almost 200 miles and refilled. dist/gal. High 20s seems the norm. I guess I should really do a long term check. say a couple thousand miles and track all the fuel purchases.

anyway, that will wait until next year. I just hanging in Afghanistan right now. diesel trucks everywhere. I get a neat little toyota 4dr pickup with diesel engine to drive around the base. It's a new truck but its mechanical injection?? kinda strange with TDIs everywhere.
1996 VW Passat B4V TDI diesel...main ride
1983 Maxima LD28..sold
1984 Isuzu P'up diesel 4x4..sold
1981 Rabbit diesel - sold
1984 MB 190 diesel - for sale...sold
1987 MB 300TDT diesel...sold
1983 Holiday Rambler 6.2 diesel Banks turbo...sold
1983 Dodge Ram D50 2.3 TD diesel for sale
gas stuff-Jeep, Lebaron, Porsche, Harley

rlaggren
Posts: 541
Joined: 13 years ago
Location: San Francisco

#6

Post by rlaggren » 12 years ago

This tank got 29.3mpg so it looks like the large tires may be a good bet even with the gearing issues. Actually I seem to recall there were one or two grades in Nevada that wanted another gear with the stock tires. The real test will be the run to Chicago - see how high into the 30's it'll get.

Rufus
82 Maxima wagon

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asavage
Site Admin
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Location: Duvall, Wash.
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#7

Post by asavage » 12 years ago

My '82 Wagon: achieves 29-31 MPG on highway trips, 25-28 in normal mixed commuting. More or less stock tire size.
Regards,
Al S.

1982 Maxima diesel wagon, 2nd & 4th owner, 165k miles, rusty & burgundy/grey. Purchased 1996, SOLD 16Feb10
1983 Maxima diesel wagon, 199k miles, rusty, light yellow/light brown. SOLD 14Jul07
1981 720 SD22 (scrapped 04Sep07)
1983 Sentra CD17, 255k, bought 06Jul08, gave it away 22Jun10.

rlaggren
Posts: 541
Joined: 13 years ago
Location: San Francisco

#8

Post by rlaggren » 12 years ago

Thanks for the benchmark Al. I think I'm in that ball park - all stock I got 28 at 68 when I hit Ca on 80 and went over the Sierras. We shall see...

Rufus
82 Maxima wagon

diesel-man
Posts: 150
Joined: 14 years ago
Location: Elkton, MD

#9

Post by diesel-man » 12 years ago

rlaggren:
I don't see any smoke when I'm going up the hill so possible the fuel delivery could be increased (very) slightly; I'll have somebody tail me up the hill to confirm this.
If you are going uphill or flat at "speed" 50? and floor it and there is very little smoke, you are looking at a nearly plugged fuel filter...not a "bombing" opportunity. :wink:

I have gotten 40MPG on a trip to Florida and described it on an old thread.

rlaggren
Posts: 541
Joined: 13 years ago
Location: San Francisco

#10

Post by rlaggren » 12 years ago

If you are going uphill or flat at "speed" 50? and floor it and there is very little smoke, you are looking at a nearly plugged fuel filter...not a "bombing" opportunity.
Hmm. I got the car from Steve and he had just changed the fuel filter (2k ago at most when I got it). I've put about 10k on it with no particularly noteworthy fueling incidents (all petro w/stanadynes additive) but maybe there's some other fuel restriction.

However, has run very well; seems to go up hills and such OK. Maybe I just don't know what to look for in the way of smoke. Guess I'll have to let somebody else floor it up a hill while I drive behind it to see what I'm talking about . <g>


Rufus
82 Maxima wagon

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