4A vs 2H. Which gets better gas mileage?

[Big Boss]

Anybody getting better mileage with Eco, was gonna give that a whirl as well or is it negligible.

I have been testing it for about a month or so now. Eco Mode + Auto start stop on did result in better mileage. The thing I have noticed with eco mode is that you also have to change your driving style. The first time I used it, I noticed I was a little heavier with the throttle input(because Eco mode really changes that) and didn't get much better MPG. Then I started accelerating slower and coasting as much as possible and cruise control whenever I got to speed. Best I got was 25.5MPG (computer and hand calculated) Doing the same in normal mode is usually about 22ish to 23ish. Wthout ASS on it drops to 20-21.

You can have eco or boost but not both

Sponsored

 

[Tricky Dick]

Anybody getting better mileage with Eco, was gonna give that a whirl as well or is it negligible.

Yes, it's worth 5-10% in my testing. It appears to detune the engine as well, not just throttle mapping and shift points.

As to the original question, there won't be any difference in normal conditions.

 

[JT58Bronc]

I have tried ECO mode in other vehicles I have owned and usually get the same if not worse MPG so I won't even try it. I'm getting 21 average in my 2 door base 2.7 SAS brand spanking new- which I think is amazing given the vehicle. I do use the start/stop though as some lights where I live are really long. I got only 18 in my 97 Wrangler with 31" tires that I sold to get my SAS. It's so powerful with the 2.7 I barely touch the gas and it's plenty fast enough. So fun to drive.

 

[Shane78]

We obviously see tons of Bronco pictures. No clue what it is, but yours in your profile picture jumps out as looking especially good. Noice!!

Hey thank you! She is a beaut, just happened to look particularly clean that day. Literally just spent 2 hours detailing, pulled it out of the garage, starts raining. At least I got a pic for proof

 

[AZ_Liberty]

I've done a few 100mi round trips on Eco versus Normal (all highway) and I didn't see any appreciable difference in fuel economy. You can tell the throttle mapping is different and that the transmission shifts in lower rpms in Eco, but other than that, little to no savings to mpgs.

Yeah, for highway driving, Eco, Normal, and Sport should all give the same MPG, because once you are in your highest gear it's all the same.

These modes change the throttle response and shift points, so they only really do anything on city streets. If you take off slowly and want to chase higher gears as fast as possible, then Eco will do that. In mixed driving where there is moderate traffic, sometimes you can get the bast mileage in Sport, because it keeps lower gears longer which means more torque with less boost.

If you treat the gas pedal like an on/off switch (like my wife) you get crappy milage irrespective of what mode you are in.

 

[Tunagates]

So have a FE and have about 3,500 miles on it. Mostly driven in 2H normal mode getting around 16.5 eveyday driving. I swear the couple of times I have driven it 4A non-snow I have gotten better mileage. Any insights on this or was it just a fluke.

Idk what im doing wrong man - 4door FE, drive 2H for everyday driving - 7k miles in, im at 13.8 mpg on the gauge.

 

[bytheway]

Idk what im doing wrong man - 4door FE, drive 2H for everyday driving - 7k miles in, im at 13.8 mpg on the gauge.

I thought I was doomed to 16mpg for life. Took my first roadtrip this week and got almost 21mpg on the way there. Heavy crosswind on the way back dropped me to low 19s but I was still impressed. Try resetting your meter. The average fuel economy gauge seems to take from a larger sample size. The trip mileage seems to calculate more short-term.

 

[DakotaGuy]

4A doesn't only engage when slip is detected, it defaults to sending some power up front from every stop, so there will be more drivetrain losses.

The axle disconnect/IWE system isn't clear to me yet, but on the trucks the front axle or wheel ends are disconnected in 2H, removing the parasitic losses of spinning those components at all times. Not sure what configuration the Bronco has.

I'm almost positive the Bronco runs a live axle system like the Ranger. There are no disconnecting vacuum hubs like the F-150. The front drive system is connected and spinning at all times. It is just disconnected at the transfer case in 2H. Correct me if anyone knows something different.

 

[VoltageDrop]

I thought I was doomed to 16mpg for life. Took my first roadtrip this week and got almost 21mpg on the way there. Heavy crosswind on the way back dropped me to low 19s but I was still impressed. Try resetting your meter. The average fuel economy gauge seems to take from a larger sample size. The trip mileage seems to calculate more short-term.

About what speed were you averaging? I averaged 19.1 going to Super Celebration, 19.3 driving in the mountains in 4A Sport, then 18.0 coming back to Arkansas in a nasty headwind. I've been pleased with the mileage compared to sticker and I don't notice any difference 93 vs 87 or 4A vs. 2H.

I'm almost positive the Bronco runs a live axle system like the Ranger. There are no disconnecting vacuum hubs like the F-150. The front drive system is connected and spinning at all times. It is just disconnected at the transfer case in 2H. Correct me if anyone knows something different.

For advanced transfer case that is true but I've seen mention of some sort of axle disconnect at the front differential in the service manuals so maybe the M190 has one? Neither has it at the hubs from what I've seen.

 

[BRBUSTER72]

Anybody getting better mileage with Eco, was gonna give that a whirl as well or is it negligible.

I believe eco helps in stop and go conditions, probably not much or at all with constant higher speeds.

 

[Hoss360]

I didn't buy my Bronco for fuel mileage, but at the same time, you'd think that it would have improved a bit from 40 years ago...

 

[Drex]

Does the A4 burn more fuel in 2H than a Bronco not equipped with one? Per my recollection the Advanced automatic transfer case never decouples from the front axle, so it always has to expend energy to overcome friction, angular moment changes, and so on. On the units without it, the wheels can freewheel at the hubs, no? I would figure that would be a measurable penalty at the pump. Anyone who understands the systems care to chime in?

 

[Saltlife4shore]

I wonder if 4A changes any mapping characteristics of the engine and trans, and the truck utilizes its power more efficiently. I can see this as a benefit and possibly better mpg's.

 

[drew707]

2. 4A pulls in the front axles that are usually freewheeling, which would likely have a slight negative effect on mileage.

Pulls in with what? The hubs are directly engaged there’s no IWE to disengage them.

 

[drew707]

About what speed were you averaging? I averaged 19.1 going to Super Celebration, 19.3 driving in the mountains in 4A Sport, then 18.0 coming back to Arkansas in a nasty headwind. I've been pleased with the mileage compared to sticker and I don't notice any difference 93 vs 87 or 4A vs. 2H.


For advanced transfer case that is true but I've seen mention of some sort of axle disconnect at the front differential in the service manuals so maybe the M190 has one? Neither has it at the hubs from what I've seen.

There are two M190 variants. Both are open but one has a Front Axle Disconnect and the other does not. Unsure of what trims get what I never dig far on it. But basically the FAD is the M190’s version of the locking diff. Maybe it’s even marketed that way I don’t know for sure. With the FAD off the driver axle is still locked up to the diff and the passenger axle goes free however since there is no IWE system they still spin with the wheels no matter what

Edit: I see it’s actually not what I was thinking. It sits laterally out from the differential on the passenger axle tube and disconnects it there. So technically there is some parasitic loss savings though not much. And it won’t lock together the diff I was mixed up. It’s a marginally effective economy feature really.

Sponsored