MPG and Previas

[Monster]

Alright, I have been driving my Previa for a couple of weeks now since my truck blew it's motor. Anyways, I filled up 2weeks ago with a full 17 gallons as it was the first time doing a full fill up in it. I have driven almost 175miles basically to and from work only and I have only a 1/4 tank left. WTF?!?! My last van got awesome gas mileage from what I remember and even my truck which I beat on got me 350 miles to a tank driving to and from work. I have done a full tune up(plugs,wires,cap,rotor,fuel filter,oil change,rear diff fluid change,air filter) and it runs beautiful, but the gas mileage is making me cry alittle on the inside since I expected better.

Any ideas?

[timsrv]

Yeah, the Previas aren't known for great gas mileage. If everything is in tip top shape the 2wd models will average about 18mpg. I'm sure other members may have had different results, but this has been my experience. I tow a 4X6 covered trailer with my All Trac and the van is loaded heavy. It is tuned well and runs good but I am only getting around 12 mpg :no:. Tim

[Monster]

Dang. I was expecting atleast 300 mile range for a tank, but I think there may be an issue or I'm just starting to get old and lose it. Lol. But I could have swore my gas was at the 1/4 mile mark this morning, I got off work and turned my van on and now its just above E:?: I'm starting to be really upset with the Previa, I love driving and really comfortable. But this gas mileage is turning me off, I at the point where I'm about to sell it and go back to an old TV.

[timsrv]

When my NA (Naturally Aspirated) All-Trac was new I'd consistently get 20 - 22 mpg. Somewhere around 100k miles I started noticing a decline and now (about 180k miles), even when solo & empty I only get around 16 mpg. All 3 of my NA 2wd Previas had higher mileage when I got them, but I kept them tuned well. If I drove like a granny I could get up to 20mpg but with normal driving (I'm a hot rod) only around 18. Based on the declining performance of my All-Trac (with age), I'm guessing the NA 2wd models should get 22-24mpg when things are new & tight. Not sure about the SC (Super Charged) versions as I've never had one. My guess is they are even worse. Tim

[Monster]

Well, I got 200 miles out of one tank of gas and not to thrilled with it. Got a buddy of mine wanting to buy it right now, but I need to find another Van asap since my truck is not streetable at the moment. Why is it so hard to find a 2WD 5speed Toyota Van?!?!:wall: lol, I'll even take an automatic.

[Monster]

I swear my gas is disappearing somehow, I came home lastnight after work and it was at half a tank. I get in today to go work on my truck and now I'm below half. WTF is going on with this van? :wall:

[timsrv]

Do you have a locking gas cap?

[Monster]

One of the first things I buy whenever I buy a new vehicle. Lol, but it is really bothering me about the gas situation on this van.

[wirewrkr]

Funny thing, I thought my early Van was sucking up gas like a fiend until the other night.
I was hit with a bout of insomnia and at 3 am drove to the all night gas station and filled it to where the auto shutoff on the pump did it's job.
Next I drove it about 40 miles west on a smooth country flat desert highway towards Arizona.
Average speed, between 60 and 65 mph.
Turned around and drove back (finally getting sleepy) to the same gas station and the same pump. Filled it and let the auto shut off do it's job again.
Not ONLY is it not getting bad mileage, it's getting GREAT mileage! used the calculator and got almost 28 mpg.
1988 5 speed two wheel drive Cargo van.
What I'm figuring, is that the gas gauge is not accurate. it is not consistent either.
Either way, that is pretty much the easiest way to tell.
When I was working at a very busy dealership on the DC beltway in 92 and 93, I only ever saw 2 or 3 stick shift Previas.
I thought they were awesome.
I hates ME an automatic.

[Monster]

Nice! I've actually ran the tank dry recently when I passed the 200mile mark on that one tank of gas, gauge works fine, the gas mileage just sucks balls. I'm in the process of purchasing a 85 TV LE with a 5speed, just need to save up for the shipping and it'll be all mine and I can't wait

[Monster]

Well, I have been driving the heck out of my van mainly too and from work. I filled up my tank last friday and this morning I was happy with it, I had 1/4 wasted and was at 70miles. I drove after work to pick up some things about 20miles one way and another 20 miles or so back home. I am now just above the 1/2 mark and now have 110 miles to the tank. Which is alittle better than when I first filled it up and got just under 100 miles to a 1/2 tank. I'm gonna try my best to try and hit the 300mile mark with this one tank of gas........ I'm determined!!!!:rol:


http://media.use.com/images/s_2/d79010263cae6cc9710a.jpg (http://www.use.com/d79010263cae6cc9710a)
http://www.use.com/images/clicklarge3.gif (http://www.use.com/d79010263cae6cc9710a)

[Burntboot]

One thing to consider is the gauge is just that, a representation (rough estimate) of what is in the tank.
It will be affected by things like braking, cornering, up and down hills... that is why they have resistors in line to slow down the readings and hopefully display a more accurate representation of what is supposed to be in there.
Throw in a little dirt and corrosion and things can get even worse.

Fuel gauges are far from perfect, but a great improvement over when we used a stick to dip what was remaining in the tank!

Track your mileage driven vs gallons used.
That is the only way to really know what your true mileage is.

BB

[Monster]

I've been using the mileage while seeing how far I can go on one tank of gas, I was just excited to see it over half a tank with 110miles put onto it. I'm at 180miles and just above the 1/4 tank mark. I'm hoping for over 200 miles on a tank of gas, I'll be alittle happier if I can squeeze out 250 on a tank of gas. And just incase, I don't speed or drive ridiculous at all. Just low and slow, I'm not in a hurry to get anywhere. Lol

[pdgizwiz]

Burntboot is correct. Gauges are there to let you know when you should start thinking of stopping for more gas, but are not accurate at all. One may show 3/4 when there is only 1/2 in the tank, or 1/4 when there is only a gallon left.
If you keep records of what your odometer reads when you buy gas, and how many gallons you buy at the time, you can get accurate numbers (and even then, subject to the accuracy of your odometer/speedometer, which can be off by a few percent). Add the date and the cost, and you can go nuts with numbers. I'm a little anal and keep track of all this in an Excel spreadsheet. My '91 Alltrac with 275k gets between 14 and 21 mpg depending on whether I'm just bonking around town a couple of miles per trip or on a roadtrip racking up a hundred or more at highway speeds. If I see those numbers change, I'll start looking for something out of whack.
BTW, my valve cover gasket is still holding oil!

[Monster]

Yeah, I reset the trip meter everytime I fill up.

Now, I actually got over 200miles to the tank finally!!! Not quite 250, but I got 212miles to the tank of gas. I'm just not pleased with the Previa gas mileage wise, I'm at a crossroads with what to do with it. I love it cause its comfy and easy to load up parts, but hate it for the gas mileage.

[maxemum610]

On hot afternoons I get a much lower reading from the gauge - as if the heat here in the tropics makes the dipstick in the tank read a lower level.
I'm not saying the fuel evaporates away purely, cause next moring it all seems good again

I think what needs to be said when we are talking about milage, is at what is the ambient temp outside when doing these distances?

At this time of year my ambient is around 30C (86F?) so I believe more fuel is used.
Cool days my Van sounds and seems to perform much better.

[Burntboot]

MAX - the difference in gauge readings due to temperature fluctuations, is more likely a bad connection than the fuel level actually changing.
Cleaning grounds may help but pulling the tank and cleaning the sender (which of course is NLA) will most likely cure that fault.

As to having more power when it is cooler. Air and fuel are both denser at colder temps so you're actually getting more of both into the combustion chambers at cooler temperatures than on a hot afternoon. The computer will keep the ratio of air to fuel the same but it cannot compensate for different densities.
So colder temps will actually induce more fuel usage (and hence, more power) not less fuel.
Just be glad you don't have to deal with "winter gas" as we do up here, designed for easier starts..... but sure doesn't go as far as the summer formulation.
BB

[batook]

I get decent mileage in my 91 Previas, but I do a lot of freeway driving. In the winter, it's something like 18-20mpg, 17 at worst. In the summer I usually see 20-22. The best I've seen is 24mpg. I have JDM motors in both of my Previas, so they are relatively low mileage engines, but I got similar mileage before when the Automatic AWD was at 300k+ on the original motor and the 5Speed AWD was at 260k before the headgasket blew.

I have fresh Denso O2 sensors in both, and clean and fully functional EGR systems/throttle bodies, which I found makes a big difference (especially the O2 sensors, before I changed those I would get 15mpg in the winter in the automatic).

Oh yeah, my driving style is "spirited/aggressive", especially in the 5-speed (usually 10-15 mph over the limit, often going 85).

In the summer I'll get to 300 miles by the 1/4 tank mark (I always fill up then to keep the fuel pump happy) and in the winter it's usually 250-280 on the trip meter by the 1/4 tank slash.

[timsrv]

Lol, I checked mine yesterday and only got 10.2 mpg (my all-trac towing the trailer) :no:. Only made it 160 miles before the low fuel light came on :doh:. Part of it for me is that crappy winter blend gasoline. My son usually gets 30 - 35 mpg with his Corolla but reported he has dropped down to about 25 mpg. We're both using out of the same storage tank, so that seems to be the common link. Both rigs run great but our driving habbits are also spirited/aggressive. When you add the weight of the cargo trailer the Previa is moving about 3,500 lbs (in addition to it's own weight). It really struggles to maintain 75 mph on the freeway & rarely shifts into overdrive (which by the way is about 70% of my driving). Tim

[batook]

Haha, that's abysmal. My 5-speed Previa is completely stripped inside, (none of the rear seats are installed, no carpet either) so it's pretty low-weight most of the time. Sounds like you need to find a different gas station! Around here, I usually try to go to Shell or Conoco, and I get the 91 octane (highest here).

I just filled up my 5-Speed AWD tonight, and it had 300 miles on the trip meter at the 1/4 tank slash, and my mpg phone app calculated 21 mpg for this last run, so I'm really happy with that, especially on winter gas. :thmbup:

[Monster]

I'm still currently getting crappy gas mileage, 230 miles to a tank is the best I can do and thats pushing it. 200-220 is about average for me but my van is also running rich, so I'm gonna spend some time replacing the o2 sensors, and try cleaning the EGR out to see if it helps

[batook]

Amazon usually has the best prices on the OEM (denso) o2 sensors. The front/upstream sensor is the more expensive of the 2 and includes 2 heater wires along with + and - leads. You can save yourself $20-30 by buying the "universal" Denso sensor and soldering the connector from your old sensor onto to bear wire leads it comes it. I have gone this route on both my vans and soldered/shrink wrapped the connections and they work great.

Front/Upstream sensor 234-4050 (universal) currently $29.99 + $2.99 shipping from seller "AD Auto Parts" through Amazon, or $43.27 through Amazon directly:
http://www.amazon.com/Denso-234-4050-Oxygen-Sensor/dp/B000C5SG2W/

Front/Upstream sensor 234-4072 (direct fit) currently $63.83 at amazon:
http://www.amazon.com/Denso-234-4072-Oxygen-Sensor/dp/B000C5UFMG/

Rear/Downstream: Denso 234-2052 (direct fit) currently $35.98 at amazon:
http://www.amazon.com/Denso-234-2052-Oxygen-Sensor/dp/B000C5YCFM/

Denso also sells a universal style for the rear/downstream sensor, but it's more expensive than the direct fit. Both versions with the diamond-shaped flange and gasket you need to install them...the only difference between the universal and the direct-fit versions are the presence or lack of the wiring connector terminal.

If replacing the o2 sensors and cleaning out/testing the EGR system don't help your mpg, I'd look to EFI problems like leaky injectors or bad FPR or something like that. I think the FSM has a list of things to check in order of priority to diagnose a rich running condition.

[Leppah]

I have a 1991 all trac. I'm getting around 270 miles per tank. I ran my van down until the fuel light came on. I think i only have a tank that's right around 16 gallons.
Most of my driving is in town, running to work, running a kid to school, picking her up, running to the store. I don't get much freeway driving.
I actually just did the lift on my van, so I'm wondering if that's going to give me less mileage per tank.
I'm thinking i'm going to replace my plugs this weekend.
I'm running a full tank of premium gas right now, so we'll see if that makes a difference at all.

[willyjake]

Old thread but I will reply anyway cause this always comes up.

So anyhow, my 91' had about 320k miles on it when I got it and mpg was pretty low....I didn't really realize how bad it was though until I replaced my O2 sensors. As others have stated here it makes a huge difference. This summer I was driving at altitude (over 8,000 ft in the San Luis Valley Colorado) on a road trip back from Mesa Verde and calculated at just under 25mph (it was like 24.8 mpg or something) which I was really pleased with (4 people in the car and all our stuff as well).

I just pulled the o2 sensor on my new previa today and have it soaking in gas overnight. I'm expecting similar results although I haven't cleaned up the throttle body or EGR passageway on the new van yet. Maintenance makes a huge difference on MPG in the Previa and not keeping up on it will see your mpg decline by almost 25% in worst case scenarios it seems.

[cb97alltrac]

I got up to 400 miles per tank on the highway on my old 95 na 2wd supercharged. My 96 doesn't do as well, don't know why. Alloy wheels help a little. Cleaning the EGR passageways under the drivers seat helps. Of course, new plugs and wires and cap and rotor help. Tire pressure helps. If your mileage is bad, then make sure no leaks from filler pipe or tank. I cut my 95 fuel filter with 140 k open once and it was surprisingly clean. 95 avg.about 22mpg overall on fuelly, 96 and 97 alltrac avg about 20 mpg, slighty more highway than city driving

[herrstrand]

Here are my mpg figures for the statistics. I have a NA 1993 Previa with automatic that runs at around 17 mpg with mostly town and short trips. At highway speeds above the point where the interlock bridges the converter, the mpg improves up to 24 mpg. There is little difference in consumption from summer to winter.

[Jonny]

Fuel consumption on my '91 is pretty much identical to batook's (post #18). It seems like there's got to be something not quite right if a tank only gets barely past 200 miles.
Just supplying another reference point for anyone searching this thread.

[tbkilb01]

My 92 at 165k still gets 19ish city and 22ish hwy. use it for camping now more than just DD. Has had an easy life. If I want economy I use the Prius or MX-5. Previa still gets better MPG than FJ Cruiser! Hauls some stuff too! Not the best on mileage. Sure is a dependable vehicle! However I still got my sites on a SIENNA! great power!

[previa tank]

I just recently acquired an 1992 previa AWD with and ABS system at 192,000 miles on it and an very nice thick folder of maintenance history mostly to the dealership. Currently I'm getting 250mpg per tank. I have yet to run it dry (which I do not like doing because of the possibility of burning out the fuel pump) and I wont, Ill fill the tank and drive a bit then fill the tank to get an accurate read of my mpg for a future post. So far I have only filled it with chevron and shell plus, as a means to clean out the fuel system because the vehicle had sat not running for almost a year.

Having just acquired it as a literal barn yard find I changed some fluids and parts; alternator (needed it, battery was still good though!), shocks, struts, strut mounts and bellows, break fluid, both differential fluids, oil (mobil one synthetic with rislone additive), transmission fluid (castrol and a couple quarts of mobil one aft).

Parts and jobs I have planned to replace and clean are many the ones related to mpg more so are; cleaning the throttle body and EGR passage way, cleaning the EGR and vacuum modular, new belts, cleaned or new O2 sensors, fluid change for the transfer case. possibly a new fuel filter. I may also change just to be on the safe side; water pump, thermostat and radiator.

My last previa an 1991 RWD with 239,000miles on it got over 350mpg on an tank. I hadn't even cleaned or changed the O2 sensors or EGR system. I always ran high quality fuel plus. I also always used rislone additive in every oil change, wich quickly and permanently got rid of an noisy lifter.

I have plenty of miles ahead of me so this will be a good opportunity to get a solid read of the changes.

[previa tank]

I filled up the tank and drove 52 miles, i burned 2.58 gallons of fuel giving me 20.15 mpg. Not nearly as bad as I had suspected. I did find out that I was around 3/4 of a quart of oil shallow in my engine witch i filled up before driving. I'm not sure if it was just my low oil that was the issue or a sticky fuel gauge preternaturally turning on the low fuel light.

I still plan to do all the above and are currently contemplating putting on new O2 sensors.

I forgot to mention in the above that I had a roof box the packasport 90 on my 91 RWD previa and also have it on my 92 AWD I know that usually takes it down a mile per gallon or 3 at the worst. Though its very aerodynamic in shape.
When I put it on my 91 I noticed that I got around 335 on a tank of fuel down from 365ish I never did let that one burn empty either or track the fuel too much I noticed that when I really had to fill it up it took 14-16 rarely more gallons.

[mjg0711]

Hi Folks;
'93 Previa, 2WD, automatic. Remanufactured engine about 40,000 miles ago. Average 20-21 in town. Highway fuel mileage is a different story depending on speed. If I keep it to 55 MPG, then I'll get 26 mpg. But if I'm running 65 - 70 MPH, then I get around 22 mpg. I've read a bit about the wind spoiler above the rear window. It supposedly will add about 2mpg. Apparently, the aerodynamics are typical of a minivan - ie. it's a brick. The spoiler smoothes out the airflow behind the vehicle where most of the drag occurs. That's why Toyota added them on later Previas.

[timsrv]

I could be wrong, but I was under the impression they only put the spoilers on the LE models with the moon roofs. Something to do with air flow past that window. I'm not saying it won't increase fuel economy, but if it was put there to increase fuel economy, then why not put them on all (including the non-sunroof models)? But then again, I'm only familiar with the 91 - 93 Previas, if they put them on the later model Previas (in all trim levels), I would be the last to know about it. Tim

[Burntboot]

Drag co-efficient for Previa 91-97 is listed as 0.35
With the footnotes:

"Toyota Previa LE S/C 1995" (http://www.theautochannel.com/vehicles/new/reviews/wk9441.html). theautochannel.com. Archived (https://web.archive.org/web/20100506141014/http://www.theautochannel.com/vehicles/new/reviews/wk9441.html) from the original on 2010-05-06. Retrieved 2010-05-02.
^ (https://en.wikipedia.org/wiki/Automobile_drag_coefficient#cite_ref-54) "1990 Toyota Previa" (http://www.carfolio.com/specifications/models/car/?car=36201). carfolio.com. Retrieved 2010-05-02.


It would appear that the wing has no significant impact on aerodynamics, at least as measured in the wind tunnel.

[man_btc]

There's this, FWIW:
http://blog.toyota.co.uk/history-of-the-toyota-previa
[In 1993] Previa also underwent a subtle revision primarily focused on improving its aerodynamics. The launch version had a drag co-efficient value of 0.35, but by altering the windscreen wiper design and fitting a rear spoiler this value was reduced to 0.32.

[buzz2401]

I've had a few over the years. My 93 NA 2wd got 21-22 on the highway. My 95 Alltrac S/C used to get 19-20 on the highway then I put bigger all terrain tires on it and it went down to 17-18. Then the mileage took a hit and was down around 15-16 couldn't figure it out . Tell the other day when checking my brakes I found the culprit, I had a sticky caliper and brake pad was almost gone. My co-worker used to have a 91 2wd and he swears he used to get 400 miles out of a tank.

[apham8]

1992 Toyota Previa LE with a recently replaced engine. It is a low mileage JDM engine, although I do not know exactly how many miles.

21.5 mpg with a good 50/50 mix of highway and city driving. Also, I do not drive my Previa slow. I typically cruise at about 68-70 mph on the freeway and I get up to speed quickly in city driving.

I only recently got the van and did do the mpg calculations AFTER having changed my rear differential fluid with Amsoil Severe Gear 75W-90 Gear Oil. Others in various applications have recorded mpg improvements with Amsoil Severe Gear. Although, I do not know if that factor contributes to my 21.5 mpg. There is a noticeable difference with the Amsoil gear fluid though. Just feels like less resistance in the drivetrain.

[celeron55]

Maybe I should've blogged about it here but I made a full EV conversion of my 1992 Previa (the third one), so here's my take on "fuel" consumption.

One thing that is clearly visible with an EV drivetrain is that energy consumption starts about 30Wh/km higher than what it settles down to after 30km or so, all of that being unrelated to the motor itself. That's at ambient temperatures of 20°C or so.

80km/h (50mph): ~200 Wh/km (~320Wh/mile)
100km/h (60mph): ~250 Wh/km (~400Wh/mile)
80km/h towing a reasonably sized trailer: ~250 Wh/km (~400Wh/mile)

City driving takes a bit less than slow highway driving, but those numbers don't really matter. These are summer numbers, at winter it's worse (270Wh/km @ -20°C 80km/h) due to cooler lubricants, less tyre pressure, snow on the road and such, not even counting for heating which can be done economically non-electrically with an off the shelf eberspacher or whatnot.

My drivetrain is a Nissan Leaf motor attached to the original manual transmission, without a clutch. 2nd gear can be used at all times. 4nd gear is used on long highway drives. 4th gear gets rid of about 30Wh/km of gearing losses as it's direct drive through the transmission and some of the gears will spin slower, causing less losses in moving the transmission oil around.

My differential oil is probably too thick as I was too lazy to go buy the proper thickness when topping it up.

My tyres are some old korean crap.

These numbers are similar to the Audi e-Tron, which is a rather small car compared to the Previa. The e-Tron is said to have a drag coefficient of 0.28, which admittedly makes my numbers make no sense. Maybe the german test labs used duct tape and cardboard? 8)

Anyway, based on these numbers the Previa's only problem is the grossly inefficient engine. Put a modern one in it and you'll get nice fuel mileage. Too bad they make all of them too tall to fit, except electric ones.

9105

[llamavan]

^^^ This is VERY COOL!!! :thmbup:

I hope you will blog more of the details, and also duplicate this post (and add some information if you're so inclined and have the time) in THIS EV Conversion thread (https://www.toyotavantech.com/forum/showthread.php?605-EV-Conversions).

Gwen