Anybody know what type of 4WD sytem is used on the hybrids and is it any different than what's on the non-hybrids.

The reason I ask is because of a post, maybe in this forum about the use of a Scanguage II in a older hybrid 4WD. They claim that it can show the % of torque to the rear wheels. The user has pictures taking off from a stop sign on what appears to be dry pavement with the guage showing 47% and going to 0% at a cruise! How can you get that more rear torque with no wheel slipage? Does a hybrid have a much different 4WD system? That doesn't sound like a good way to save gas to me!

 

It's the same system. The reason that guy was showing torque split is because the system reacts and kicks in so fast that it makes corrections before you can sense wheelspin. It analyzes the wheelspin many times per second and makes adjustments. The tiniest bit of wheel spin (such as on hard take off) will induce the 4wd system to send power to the rear wheels. You don't necessarily hear or feel the wheelspin. After it determines that the wheelspin event is over it goes back to 100% fwd and zero splitting.

On my Dodge Caliber (front wheel drive 300 hp) the stability control and traction control will tug at individual front wheels under hard acceleration as it detects wheelspin conditions and you have no sense of the wheels spinning. There is no tire noise and no feeling of them actually spinning but you can feel the control system applying brake pressure to the different wheels. When you disable the traction control you don't feel the same tugging action and you get the wheels actually spinning. Basically today's sensors react unbelievably quick, before your senses can notice what is happening. While my Caliber is a totally different vehicle, most manufacturers are all using the same technology and sensors are pretty close in specifications.

 

If it reacts so fast to go into 4WD and out, do you think that he'd have time to take a picture of it? I don't think so. What does it take to break traction on dry paveemt? He didn't say that it was a full throttle start either! I asked the same questions of the poster but they never responded.

 

While it reacts extremely fast to engage 4wd, I've never known how long it keeps 4wd active once it is engaged. That was a question I asked myself many times when I drove an 06 xlt 4wd, I could never tell when the 4wd system disengaged. Who knows how the algorithm of the 4wd control system is setup ?. Snapping a picture doesn't take that long if you are set up to do it in advance of the event, like 1-2 seconds max ?, enough time to have the 4wd still enaged. I doubt the 4wd system stays engaged for a 1/4 mile down the road after it engages on dry pavement, but it could theoretically stay engaged for the first 30 feet or so.

The poster would be best to answer how he did it. It's been a while since I last read that post, but I thought he accelerated off the line with a bit of gusto, likely enough force to activate the 4wd system. You don't have to hear the tires chirping to have the 4wd system activated, and how long it remains engaged is anyone's guess. I know the current generation claims to have the system engage and disengage very quickly if you watch their little video demonstration on the Ford website, the previous generation may have disengaged based on a different algorithm.

 

The poster stated from a stop sign, no mention of pedal to metal! If you don't lose traction at a front wheel, 4WD shouldn't engaged unless under "some" sort-of heavy throttle. Tires chirp on a Ford Escape? Are you kidding?

I found the post interesting but the poster left me hanging! I looked up the ScanGuage-II but the site only mentions showing 4WD ON/OFF on the hybrid only, nothing about the torque percentage so there is some difference right there.

 

My '02 V6 Tribute FWD will easily smoke the front tires while my '09 4WD won't make a chirp, yet the 09 is clearly the quicker vehicle with a more aggressive 1st gear. Having some torque always going to the rear tires must make a difference.

 

With the "on demand" system from a dead stop, all the way to the floor, you should be 100% rear wheel drive from what I've read about the system. I could smoke the tires on my 97 Ranger too. The rear was so light, I had to use 4WD when in a little snow just to keep up with a conventional vehicle.

 

I found and reread the post which included a link with more details. The following is a quote from the percentage of torque and a bit about the conditions, etc.

>>
Pulling away from the stoplight with a 47.4 4WD value. I have seen as high as 62.6 with my leisurely driving style.
>>

That sure isn't a description of a person with a lead foot!! I'd still like to know why a hybrid 4WD would send so much torque to the rear wheels? Maybe what they are reading isn't really rear wheel torque?? These people seem to be poking around in the PCM looking for the PID that would show rear wheel torque by trial/error not really knowing if it exsists.

 

The hybrid Escape has a third electrical motor that drives the rear wheels. Could be that the electric motor is that much quicker in reacting vs the engine.

 

Regardless, why does is need 4WD leaving a stop sign with a leisurely driving style? No wheel spin or heavy throttle, why is it sending torque to the rear wheels? Not all hybrids are 4WD either! Makes no sense to me at all.

 

The Escape Hybrid works like most other hybrids — supplementing the 4-cylinder gasoline engine with an electric motor for low-speed all-electric-power driving. Acceleration is satisfying when the electric motor helps propel the vehicle, because torque from electric motors comes on instantaneously.

There are other similar quotes out there.

Whether or not you stomp on the gas, the electric motors kick in to assist in accelleration. My AWD hybrid, even when it starts cold, will show the electric motor assisting while driving. I'm guessing that it's in the software to help with gas mileage.

HTH

 

Both of my Hybrid Escapes are front wheel drive only but I am near 100% certain that the 4WD version does not have an additional electric motor to drive the rear wheels. I believe it has the same rear differential setup as the other 4WD Escapes. The Hybrid Highlander (IIRC) has the read electric motor but not the Escape.

It doesn't happen that often but there have been occasions where I've stood on the gas pedal from a dead stop (or even from low speed) and the tires most certainly spin. We aren't talking smoke show but it will make some noise for sure.

As to the original topic, my theory on this would be the reaction, or refresh, time between the vehicle computer and the Scan Gauge. I doubt very much if everything that is displayed is instantaneously accurate.

 

The Scan Guage has a slow, medium and fast refresh rate.

 

Relative to what though? I guess what I am asking is how much time is there between the computer sending some piece of data and the scan gauge displaying it. How often does the computer send information? Does the scan gauge display EVERY piece of information that is sent or does it display every "X" number of data?

 

I took a casual look at the manual for the Scan Guage, some of which was confusing. It appears that you send/request data, data received is processed, formatted, etc. You must interpet the data which means room for error to me. I assume that the refresh is how fast you repeat the request. The Scan Guage can display four different values.

The user credits some other user for finding the PID for 4WD torque to the rear wheels which they "thought" exsisted! Whatever it is shows 47.4%-62.6% accelerating from a stop and 0% at a steady speed.

I can't see 4WD being enabled under the driving condition stated and whatever PID they are monitoring, it isn't 4WD torque to the rear wheels.