4x4 stuck causing drastic MPG loss

oooh, ok because i figured out how to customize it, but i didnt get why his was showing the trip summary with 3 different numbers on screen. i can't add anything to the bottom page for some reason, i hold the menu button and it asks if i want to customize it and i say yes and it just goes back.... go to settings, i still see no option to add items to the bottom screen.

thanks.

 

Bottom screen is always blank. Seems like they would've made it where you could just delete everything from a screen instead of having a dedicated one that's completely blank.

 

Pardon my ignorance, new to trucks here, but one can't simply drive around with 4x4 engaged?

 

Well you could. But turning would be a bitch and you may break something if it gets in a bind. Generally not recommended to have 4wd engaged unless you're on a loose surface or only going in a straight line. It's not like the awd vehicles.

 

Glad i joined the forum
Thanks

 

I don't think that was the problem. I think I still get better mileage than that in 4h on the road. I don't do it much because it's not good to do according to the book, but have done it to give the t case some oil when going straight on the freeway in traffic

 

Low fluid and an odd shifting transmission are totally different than a truck stuck in 4wd. Is this your first 4wd?

 

You would notice the power sent to the 4 front wheels hence 4wd

 

seriously. this doesn't make much sense to me. though i'm not really mechanically inclined, i've driven around with 4hi before and yes the steering is different because your front wheels are now powered but beyond that the truck provided no feedback to me that i was doing anything wrong. as someone who lives in the northeast, i imagine myself driving to work in the winter at speed in 4hi through the snow along my normal commute.. this can't possibly be an issue, right?

 

With snow on ground not an issue, dry pavement yes

 

This is not my first 4x4. I have had several. My first truck was a 89 toyota sr5 4x4. It had manual hubs. And I am not saying I was driving in 4hi or low but only that the truck was malfunctioning. The only thing I did was adjust the 4x4 several times. Also, I did hear some grinding which is why I took it in to the dealership. The mileage was 12/13 regardless of the duration of the trip. The 2.9 was just the trip I happened to take a picture of. If you look at the other pics it shows my best as 13.3 mpg and my current average was 12ish mpg. This shot up immediately after I adjusted/played with the 4x4. I heard a similar grinding when I was taking it from hi/low to 2wd several times. (I only heard the noise once while adjusting) I dont need people to say I would notice or not if it were in 4WD vs 2WD. I am simply offering up my experience and results. Other have asked me to comment when/if I found a remedy. This might be an issue if the 4x4 system is not functioning correctly and resulting in a 30% loss of mpg. For those of you who drive your truck on dirt roads or often take it off roading this might not ever impact you as you prob engage your 4x4 system regularly. For those of us in the city who might only get to take it off road once a month or so, this could shed some light on a weird issue. I am concerned with the damage that could have occurred in the tcase.

 

this....

 

If you don't ever use your 4wd at least once a month engage it to lubricate the system. the guy I bought mine from did some gnarly off roading, but said when he wasnt using it he'd engage it once a month to keep it lubed up and it was still running like a champ at ~330k miles when I sold it.

 

I'll bet you can put it in 4 hi and drive around and get better than 12 mpg. When I first drove my truck it wasn't averaging well. Was averaging 15. Now I'm at like 18. All city driving currently. I've never see 4 wheel drive have that big of a swing on mpg. Also that's tank average. So if the truck has been sitting there idling while they were showing you how to use your radio or something at delivery or your in a parking lot that's all going to have an impact on the tank MPG. Also depending how you drive your still adapting to the truck. You might of been harder on the accelerator because it doesn't have a lot of power down low. I know I was. Now I just accept it and if I need I'll mash it or hit the ect button when I need the power quick.

 

Interesting... good post OP.

One thing I love about this Taco and my 2nd gen was how constant MPG was with or without 4x4 engaged. I only saw a minor 2 mpg drop when I cruised alot in the dead of winter with 4x4 on.

 

Yup. Think the book says that too. Run it for about 50-100 clicks a month.

 

I went though a thousand miles and got around 13mpg on average. I did the math at fill up and watched the tank miles per gallon and the trip. The best I had ever got regardless of how I drove was like 16.7 on the highway. It had nothing to do with trip length or driver usage. Once I activated the 4x4 and toggled between all the low high and 2wd, it had corrected the condition giving me 17/19 city and about 22/24 hwy regardless of distance or how I drove it... If I mashed the gas and was crazy on it Im sure I would get lower MPG but keep in mind, I was trying to improve it and watching it constantly. I wanted to see what the problem was. I am telling you, the problem was the 4x4 not disengaging fully. I dont care what some people say about it being only on or off... thats not how things work in the real world. once I fully disengaged, the noise went away completely and my MPG shot up by 30% driving the same exact way I had been doing before.

 

if you understand how 4 wheel drive works you'll see there is 3 possibilities. 1) it's engaged, 2) it's disengaged, or 3) the actuator is stuck and its perhaps partially engaged. If that happens your going to get a bunch of grinding and the truck isn't going to go far before something fails. While I can't fully give you an explanation with the info you provided I can pretty much assure you it wasn't partially activated. And even if you drive around on a full tank of gas right now I'll bet if you drive the same way you'll get better than 12 mpg in 4 wheel

 

To add a little more detail...

When you have 4WD engaged, the front and rear driveshafts are connected and make the same number of rotations. When you're going straight this is fine, but when you start to turn the front axle and rear axle travel different paths, and thus different distances. The tighter the turn the greater the distance differential. To accomodate this the tires have to slip some; easy on dirt, gravel, snow, or wet pavement. Not so easy on dry grippy pavement, leading to "hopping" or even breaking parts.

All-wheel-drive avoids this by adding a differential between the front and rear driveshafts. Downside of that is that all the power can go to the single wheel that has zero traction. With 4WD you'll have power delivery to the other axle even if one is spinning freely.

EDIT: more info at http://www.tacomahq.com/4546/toyota-tacoma-4-wheel-drive-explained/

 

ill be willing to bet some of it is because of your wheel and tires you upgraded to. Are those 10 ply?