Query re: mileage difference between 2WD and 4A

[Richard Hinsley]

You should be able to handle 2wd on wet pavement with all the traction control these days. Man up.

 

[TwizzleStix]

You should be able to handle 2wd on wet pavement with all the traction control these days. Man up.

Bless your heart Richard...

 

[Mister Pinky]

I used 4A for a trip in the snow and wet for the first time today. I monitored the Power Distribution page in the gauge cluster. In 4A, there is always some power going to the front wheels. That, combined with the fact that the transfer case, front axles, and hubs are all engaged, means that you will have a loss of MPG over just running in 2WD. But as somebody mentioned earlier, if it saves you from putting the truck into a guardrail, what’s the difference of a few MPG?

 

[FordTechOne]

I think it's been covered, but more components moving (to speed up, then slow down) with hubs engaged. As said, even under very modest acceleration, some power vectors to the front which adds to the hit.

I've found it is probably shy of 1 mpg to run in 4A. Lots of rain here and I use it in really heavy rain, but not light to moderate rain. I also use it on steeper roads, even if dry - saves the rear tires. And the steeper roads it provides a more planted feel.

I'm of the mind that whether you need it or not, you should use it about once a month. Not sure if that artefact from manual hubs carries over to these or not?

On 2019+ and 17/18 models that have had the TCCM software updated, the IWEs (hubs) will be engaged on a cold start regardless of 4WD mode and will remain engaged for the first few miles of driving. This circulates and warms up the front diff fluid and allows time for the system to build vacuum, which is used to hold the IWEs in the disengaged position.

 

[jabroni619]

Yes. pretty sure mileage takes a hit in 4A as it will send some power to the front as well, even on dry surfaces. someone smarter than me will have to explain why.

From a dead stop, it will always send power to the front, this is likely to prevent slippage should you be in slippery conditions. While cruising, there shouldn't be any power going to the front. The front hubs remain locked so you'll feel more drag on the steering wheel but the only power going there during normal cruising would be from the viscosity of the fluid in the transfer case surrounding the clutch packs. That is unless the traction control system senses slippage, it will then engage those clutch packs as it sees fit to appropriate some power to the front.

Under moderate and heavy acceleration, it appears to send power to the front as well. Again, probably to counter any slippage before it occurs.

 

[amREADY]

On 2019+ and 17/18 models that have had the TCCM software updated, the IWEs (hubs) will be engaged on a cold start regardless of 4WD mode and will remain engaged for the first few miles of driving. This circulates and warms up the front diff fluid and allows time for the system to build vacuum, which is used to hold the IWEs in the disengaged position.

Next level info. Very informative, thanks.

It also explain why sometimes I feel like I am in 4A when cold, but check the selector and it says 2H..

 

[rtmozingo]

You got a lot of good (more importantly correct) answers here OP, but as a SCAB owner to another SCAB owner you'll learn to love 4A.

You'll occasionally lose grip on dry tarmac in normal mode, let alone sport. If the roads get wet 4A is nearly a must. Don't be afraid to use it. The fuel economy hit is minuscule, and the component wear is negligible. Your safety (and fun) is of much more import.

Personally, if the roads are a bit wet I go Normal + 4A; if they are really soaked I'll go Weather mode (defaults to 4A, was also nice for our snow day last month). If I'm serious about playing in Sport mode I'll also go 4A + TC off.

You should be able to handle 2wd on wet pavement with all the traction control these days. Man up.

And do you have a Supercrew or SCAB? There's a notable difference. SCREW is super easy, the SCAB will get away from you. Yes, TC works very well, but better to be proactive than reactive. There are situations where being in 4A would save you from something TC could not.

On 2019+ and 17/18 models that have had the TCCM software updated, the IWEs (hubs) will be engaged on a cold start regardless of 4WD mode and will remain engaged for the first few miles of driving. This circulates and warms up the front diff fluid and allows time for the system to build vacuum, which is used to hold the IWEs in the disengaged position.

Always show up with the great insider info. Do you recommend getting this update done, and how would one go about requesting it?

 

[FordTechOne]

Always show up with the great insider info. Do you recommend getting this update done, and how would one go about requesting it?

The update is only necessary if you are experiencing a concern with IWE engagement. Otherwise it's nothing to worry about, since no noise means the system is functioning properly.

 

[Heeter87]

On 2019+ and 17/18 models that have had the TCCM software updated, the IWEs (hubs) will be engaged on a cold start regardless of 4WD mode and will remain engaged for the first few miles of driving. This circulates and warms up the front diff fluid and allows time for the system to build vacuum, which is used to hold the IWEs in the disengaged position.

@FordTechOne on older 4WD trucks I was under the impression that it was good practice to drive a few miles in 4WD on a regular basis to keep everything lubricated and running smoothly. Does this eliminate the need for doing that in the raptor?

 

[FordTechOne]

@FordTechOne on older 4WD trucks I was under the impression that it was good practice to drive a few miles in 4WD on a regular basis to keep everything lubricated and running smoothly. Does this eliminate the need for doing that in the raptor?

Yes, on trucks like Super Duty that have mechanical locking hubs, it is good practice to periodically engage the hubs and/or 4WD to circulate the fluid and rotate the joints. This is not necessary on F-150 since the hubs are engaged on every cold start.