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First time using auto 4wd extensively. Horrible MPG

bloggs

By bloggs
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bloggs New Member

bloggs

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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!

 

This is kind of what I was wondering about since my sensors seem to be acting a bit oddly anyways, and I know there is some assists with them where it breaks slightly. I didn't get a chance to turn off the sensors today and try it again. I will give it a shot tomorrow and see if it improves things at all.

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bloggs New Member

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Also, thanks a lot for the input, everyone. Personally, I have used auto 4wd on my last several vehicles during certain conditions and have kind of grown accustomed to it. I work in a larger city and live in a small one, so I get a bit of a variety in road conditions and plowing statuses on the trip between the two. In the little town where I live, we have a couple inches of snow that gets left on anything but the main streets, and in the larger city it's pretty much always dry on all but the back roads. I certainly don't need 4HI for the trip most days, but I've really grown to like the auto for times when I need to turn out onto an otherwise dry busy road from a pile of snow and ice on a side street. There's nothing like that moment of terror where you're halfway out in the street in front of a semi and your rear tires spin out.

 

I've had two nearly identical 1500s as my last two vehicles, and hadn't seen anything like it in either. In fact on my last one (2012) the mileage between 2wd and auto was identical. I thought I'd ask to see if everyone would just tell me to put a couple hundred miles into it and all the 14s act that way at first or something.

 

After seeing Ventilators comment, I'm going to try turning off all of the sensors first so I can at least tell if I'm dealing with a xfer case issue or sensor wackiness combined with auto assists, then take it in. It needs an oil change and the xfer case software update anyways. I'll be sure to come back and update in case anyone else finds this thread later on as well.

MikeNH Senior Enthusiast

MikeNH

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I'm on with what everyone said, there is no harm that can come from using auto mode on inconsistent-condition roads. I've been doing it for almost 4 years and close to 70k miles. I wouldn't leave it on all the time or use it in the rain like I've seen some mention (though I live where rain doesn't make the roads all greasy like it can in some places) but after a storm most of MI is like what is described above- some places get cleaned up quick, others not so much.

mossbum Enthusiast

mossbum

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I never had a single issue in any of my GMCs when running in AUTO and I used it a lot on my 10 and 11 but not much on my 05. It's one of the features I wish I had on my current Ford.

MikeNH Senior Enthusiast

MikeNH

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One interesting observation I remember from last winter is that it feels like the front axle is disconnected when coasting- so if I'm driving around town on a road that I don't feel is justified for normal 4HI use and go around a corner I may let off to coast and then the truck starts understeering/plowing if it loses traction whereas running it in 4HI or staying on the gas keeps things in order. I don't think it's a malfunction or anything, as I recall this was how the AWD system worked on Hyundais when I was at the dealership. I guess it's just some insight as to how the system works (I have a 2011 BTW).

Jon A Senior Enthusiast

Jon A

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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!

 

What sensors are you talking about? The parking sensors/assist system won't apply the brakes, just beep at you and vibrate the seat. The collision avoidance system will shut off your cruise control in addition to that, but won't hit the brakes.

 

The only system that can actually apply the brakes without your foot being on the pedal is the stabilitrac system. So unless he was fishtailing down the road some system applying the brakes shouldn't be the issue.

fondupot Senior Enthusiast

fondupot

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What sensors are you talking about? The parking sensors/assist system won't apply the brakes, just beep at you and vibrate the seat. The collision avoidance system will shut off your cruise control in addition to that, but won't hit the brakes.

 

The only system that can actually apply the brakes without your foot being on the pedal is the stabilitrac system. So unless he was fishtailing down the road some system applying the brakes shouldn't be the issue.

 

I think he meant wheel sensors. If there is a bad wheel sensor, it could think the truck is slipping. which would cause the traction control/stabilitrak to turn on. Which applies the brakes to correct any slippage.

TJay74 Senior Enthusiast

TJay74

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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!

 

 

I don't know where you got this info, but the front sensors have no bearing or affect on the brakes in the trucks at all. We do not have the active/adaptive cruise control on the K2 trucks (as of now) so there is no way the front sensors would be activating the brakes.

Z45 Senior Enthusiast

Z45

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Automatic transfer cases will have the characteristics of both the Part-Time 4WD and the AWD systems depending on the mode selected. If the transfer case is operated in 4HI or 4LO, it will behave as a Part-Time 4WD system. If it is operated in the Auto 4WD mode, it will behave like an on-demand AWD system.

Isriam Enthusiast

Isriam

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like i said its your truck, use auto when you want. ive spent enough of my money on transfer cases, i'll never use auto, and if i need 4wd i'll use 4wd.

bloggs New Member

bloggs

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I tried turning off the parking assist today, and drove around 40 miles in a combination of highway and city driving. MPG shot up to close to 14 again. The engine seems to be able to drop into v4 about like I'm used to seeing again, and I didn't notice any of the dragging sensation. At this point I'm not 100% sure if that was the issue or not, but it seems possible since the parking assist would feed off data from the proximity sensors. I'll take it in anyways, but hopefully that will get me by until I can get an appointment with them.

Jay700 Enthusiast

Jay700

Posted
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Auto is for soccer moms the mechanics told is at the dealership. It's really cool until the clutches are junk then you get your wallet out and bend over. Like they said either u need 4wd or u don't y destroy those clutches? Unless you want too throw good money away.

SouthernSilveradoGuy85 Senior Enthusiast

SouthernSilveradoGuy85

Posted
Posted

Auto is for soccer moms the mechanics told is at the dealership. It's really cool until the clutches are junk then you get your wallet out and bend over. Like they said either u need 4wd or u don't y destroy those clutches? Unless you want too throw good money away.

 

Actually the only time for me where auto 4x4 will come in handy is after a snow storm where some places (mainly hills and intersections) are still slippery enough to need 4x4 or a FWD car but where other parts of the roads are fine. Those situations I would just keep it in 4hi which can't also be good for the drivetrain on the parts of the roads that are good. Other than that I just keep it in regular 2wd.

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