First time using auto 4wd extensively. Horrible MPG

[fondupot]

If auto were so bad why would it even exist?

 

that being said, the whole "shift on the fly" system is fragile. I broke my encoder motor on my 2010 the 2nd time I used 4wd by shifting from 2wd to 4auto while doing a very VERY slight roll.

 

Now I always put the turck in neutral and come ot a full stop when changing.

 

Btw, I just drove auto4 this morning on my 14 mile trip to a client. It's been raining and the temp is dropping fast down here. This truck is like ice skating on wet roads.

 

I reset my trip meter, I got just about 16mpg on that trip, which was ~70mph the whole way. I did some stop/start tho for about 5 miles of that tho.

 

You're wasting your time if you think you need to come to a stop and shift into neutral when changing the transfer case. That 2010 you had was just a fluke.

 

On rainy or snowy days, I will flip back and forth between 2hi --> auto or 2hi --> 4hi and back to 2hi a few times when driving. All at the turn of the knob, at any speed.

[darkfox1]

Well, I hope you're right.The shop told me people break encoder motors all the time and that I had to be completely stopped or it'd strip the gears.

 

You'd think if that were true the DIC would flash PLEASE DO NOT MOVE DURING 4WD SHIFT or something ya know?

 

either way, better safe than sorry imo. That dealership's sales area was nice, but the service waiting room smelled like urine and had very uncomfortable chairs.

[Ventilator]

The only time I am in AUTO is when transferring from 2H into 4H. It's either I need 4WD, or I don't.

 

Last year when travelling ice and snow I was still getting 22-23 MPG in 4 H @ 45 MPH on the highway, as long as the truck (motor and tranny) was already warmed up. This was only about a 1 MPG drop from my normal mileage. The remote start ups, cold start ups, cold tranny fluid, cold tires, winter blend gas are what tanks the gas mileage in my truck, not the driving once it is warmed up.

 

So, I'm not a fan of the AUTO, even though I tested it out a few times last winter. It actually got me stuck temporarily once last winter in my driveway of all places. We had a major snowstorm, huge drifts, had to go play. I don't think it was the AUTO so much as it was the damned TC and Stabilitrak crap. Once I turned that crap off and put it in 4L, it walked right out of there.

 

Anyways, I like to have total control in situations where I really need 4WD. I just have to remember to turn off the crap first. I get between 21 and 22 MPG overall per tank in the spring/summer/fall, but when winter comes with winter blend gas it drops down to around 18 to 20 MPG in the extreme cold. The worst mileage I ever had on a tank of gas was while playing in the snow, in the dead of winter last year was 17 MPG on winter blend gas and remote start ups.

 

I just cannot understand how the gas mileage could ever get below 12 MPG, unless you are towing something big in hill country. I can't even fathom single digits.

 

My bet is your front sensors are braking your vehicle, and once you are above 25 they are still trying to brake, but the motor has taken over at that point. Feel your hubs or rotors after a short drive, bet they are HOT! I got the rear sensors, because they are nice for backing up safety, and hooking up a trailer. The camera is also nice, but I'll be damned if I want sensors on the front of my truck telling me how to drive. That is what the wife is for!

[TJay74]

Same here. I put it in 4HI while in the garage, once I got to the interstate I went over to 4 Auto and then once at work back into 2wd. no issues ever.

[SouthernSilveradoGuy85]

Something is definitely wrong. My 98 in 4hi still got about 7 I believe. As for when to use 4 auto, I keep mine in regular 2. 4 auto is when it's times where you might need 4hi but not the whole time you're driving, like when it's been snowing and it's melting where it's some wet spots and some icy spots. Everybody says to not have it in 4 auto all the time because sometimes it can kick in just from a bad enough rain. I've also noticed that you don't even have to put the truck in neutral like you used to, it's shift on the fly which is nice if you need it to shift without touching the brake trying to shift.

[KARNUT]

As far back as I can remember you could switch back and forth between 4wd high and 2wd high while moving at any speed.

[pm26]

As far back as I can remember you could switch back and forth between 4wd high and 2wd high while moving at any speed.

That's been pretty much the capability on most 4WD vehicles with auto front hubs. It is only when shifting to 4WD Low that you must stop first.

[SouthernSilveradoGuy85]

As far back as I can remember you could switch back and forth between 4wd high and 2wd high while moving at any speed.

 

Ya but you used to have to still put it in neutral first. Not sure when ti started but the 14+s can shift on the fly without taking it out of gear. Even in and out of 4lo. That doesn't mean much if you're just going to drive in the snow, but if you're off-roading having to put it in neutral can be the reason you get stuck instead of almost stuck and work your way out.

[Ventilator]

Well, I hope you're right.The shop told me people break encoder motors all the time and that I had to be completely stopped or it'd strip the gears.

 

You'd think if that were true the DIC would flash PLEASE DO NOT MOVE DURING 4WD SHIFT or something ya know?

 

either way, better safe than sorry imo. That dealership's sales area was nice, but the service waiting room smelled like urine and had very uncomfortable chairs.

If you are shifting into 4L, then yes, you need to be in neutral, preferably stopped.

 

Read about it in your manual. Shifting from 2H to AUTO to 4H can all be done on the fly.

 

Back in the day, we actually had to get out and manually lock in the front hubs, and if frozen a nature call could help, preferably stopped. LOL

 

I will admit, when it is extremely cold, I cringe a little when shifting on the fly, but until the warranty is up, I'm not going to worry about it.

[KARNUT]

That's been pretty much the capability on most 4WD vehicles with auto front hubs. It is only when shifting to 4WD Low that you must stop first.

Ive been using 4wds for 40 years with my work. The only time you would need to stop was going into 4wd low. You wouldn't want to run on the hwy all the time in 4wd high even in the rain. The reason I started buying the Z71 was the auto 4wd, if you left it in auto 4wd the only harm was a couple miles per gallon hit. You really wouldn't want to leave on but you could.

[bladz1454]

...last year I drove in Auto for like a month, saw a slight hit to MPG, bigger hits when in snow. Truck ran like a champ and tranny still runs like a champ. Other than Jiminy Cricket living inside my 4WD controls - I think Auto is fine for long periods.

[SouthernSilveradoGuy85]

In my 98 you wasn't supposed to come to a complete stop to go in or out of 4lo. If you stopped it would be a hard clank. You had to go 1-3 mph.

[KARNUT]

You sure wouldn't want to do it while your tires are spinning, but otherwise ok.

[newdude]

 

I know for a fact, that Auto will break your transfer case, and when you take it to the dealer they will say yea, we know, don't drive in auto.

 

Put your truck in auto and then do a slow tight turn in a parking lot. You will hear all 4 wheels grab and release. The transfer case thinks your vehicle is slipping, grabs, then releases. You WILL break something by driving in auto for long periods of time. Not by driving 60 down the interstate in a straight line, but by daily city driving of turning into parking spaces, and anywhere else it will grab and put strain on the transfer case.

 

But do whatever you want, its your truck.

 

Dude lay off that crack pipe...Auto 4x4 does NOT bind because unless there is a need to transfer power to the front axle, the transfer case does NOT send any power to the front axle. Sure the front end is locked but it won't bind under turns.

 

Quick rundown. Don't use Auto 4x4, 4x4hi or 4x4 low on ANY dry pavement period. Auto works great in the winter time (I had a 2012, used it frequently and had no problems). Use 4x4hi when it gets trickier and 4x4lo if you really really need it.

[waumo1]

OP - your vehicle is screwed up, take it in. Auto 4WD should NOT do that - period.