AccraBob
Well-Known Member
You're right...after I noticed the tight turn chatter in 4A, I started using 2H at all times when on dry pavement.
Rumbling noise on turning 2017 exp LTD EL
- Thread starter Cynthia2963
- Start date
Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.
Rod Smith
Member
I too had a very noticeable vibration that felt like I was going over rumble strips. It occurred in low speed turns, left or right. By the time I got my 2017 EL to a ford dealer, the shuddering had stopped. My fault for waiting over a week to go to a dealer. I was on a family vacation. I was convinced the noise was coming from the rear of my car. The dealer found nothing wrong. 11,000 miles on my Expy.
Last edited:
Sorry, I don't mean to be a contrarian … but I've run in AWD and 2H in as exact same conditions as I can manage and I can't detect any significant difference in mpg. Done this many times for example cruising on the interstate with cruise set at a specific speed on fairly flat terrain. I used to be a Test Engineer so I know this isn't a perfect test but in the past several years of testing I've never seen a detectable difference. Just a data point FWIW. Has anyone else ever tested that theory?
I have, and saw the exact opposite. Hence my statement.
4A is not AWD. It is not driving all 4 wheels all the time. Things have to engage. You can feel it when 4A is on, and there is slip, there is a definite engage moment, when the front engages.
4A is merely 4WD, where the computer engages 4WD for you and locks the front hubs. It is not AWD.
Sent from my iPhone using Tapatalk Pro
Hmmm … I typed AWD but should have typed 4A because that's whats on the switch in an Expy. We shouldn't get hung up on industry standard terms anyway, this all 100% Expy. I've drivin nothing but Expys since 1999 (on my 3rd now). I have never felt any engagement of the transfer of power to front wheels in any Expy that I guess you would have with 4A. Its always been totally un perceptible to me but maybe I'm not very good at sensing those things. Its my understanding that it happens at the millisecond time frame and it adds power in very small increments, like 1% until it achieves the traction goal. The system senses the slip of the rear tires (difference between front & rear axles rotation) and adds power to the front tires to equal the rotation of the rear tires. Or something like that. Of course there probably have been many versions over the years since 1997 and the newest system is nothing I have experienced since my latest Expy is a 2014.
What test did you run to determine the mpg difference and what was the difference?
If I might ask. Its fair to ask, right? Has anyone else experienced an mpg difference or are we the only 2 people who tested it?
I'm not all hung up on being right, I could be wrong easily. I just have never seen an mpg difference and thought that might be useful experience. I like to know what is right though.
Yeah I’ve never done it. I got to 4hi to boost launch Thts about it. I very rarely go off-road. Mines more of a pavement princess that’s hauls ass and looks nice
Even on pavement … I truly believe 4A is safer on wet and snowy roads than rear wheel 2WD. I have definitely seen rear tire slip in 2WD when pulling out from a stop onto a main road in wet weather. Much less so or never in 4A. I would rather just leave it in 4A so I don't have to try to remember to switch if it starts raining. I've heard some on here like 2WD because they enjoy sliding around corners. With hydroplaning and other wet factors I'll take traction where I can get it!
I had to put it in 4Low couple weeks ago pulling out of a gravel driveway up a hill. If I left it in 4A … it was digging a hole with rear tires making a mess. Pop it in 4L and better for the gravel driveway. That was like 0.001 mph so the 4A (power to front) never had a chance to kick in.
Yes, 4hi, TC off, advanced trac off, Rpms to 2700 while holding the brake, then she gone. Only when I race
Standard, Run a tank through, test MPG, do the opposite, run a tank through. Same normal driving around town, with no long trips. We did the testing on our previous 15. Now we have a 17.
I record and calculate MPG for every tank. So it was easy to see that 4A hurt the MPG, both the tank before and after were 1.5 MPG higher.
Our 4WD system itself has ZERO torque modulating capability other than engaging the front driveshaft and locking the hubs. It is either on or off. It is basically the same basic system as the F-150. It can use the brakes to assist torque distribution from side to side, Example, brake the wheel that is spinning to send power to the wheel that Isn’t, because the front Diff is open. The rear can be a limited slip if it has the appropriate option pack. If the front drive shaft is engaged, 50% of torque is going forward. There are no clutch packs to vary the torque distribution in our trucks.
The AvanceTrac system does a real good job in the Expy at using the brakes and modulating power to keep the vehicle moving. Driving in slippery snow, I can feel and hear the system working.
Sent from my iPhone using Tapatalk Pro
Last edited:
No clutch packs in rear diff?
Similar threads
