AWD vs. FWD Performance...

[wwest]

AWD would probably be the quickest in acceleration IF an over abundance of horse power were available. Road or street driven car are not designed to burn rubber for the full quarter mile. Mazda "AWD" is not a true AWD in that at maximum, only about 50 power can be transfered. Vehicles with true AWD like Porsche, Audi and Subaru have ALL 4 wheels driving ALL the time and can transfer up to 80 % of the power to the rear to help acceleration.

Insofar as I know Porsche has NEVER been brain dead enough to transfer "up to 80% of the power to the rear".

Maybe up to 30% to the front.....

 

[wwest]

Actually your info is completely false. Please quit spamming multiple threads with the same post complaining about your problem. Sorry you are having trouble, but your problem seems to isolated. I have over 40k on my CX-7 and no problems. The AWD system is actually one of the best in its price range, excellent system. This is how it really works:


Here is the explanation right out of the Mazda training manual:

"The CX-7 is equipped with Mazda’s new active torque split all-wheel drive system, which
debuted on the MazdaSpeed6, featuring a more aggressive transfer of torque to the rear
axle in accordance with driving conditions. This intelligent system achieves a satisfying
balance between the interactive control over the vehicle that makes it particularly enjoyable
to drive, and confident handling stability necessary for snowy, wet or other uncertain road

surfaces/conditions; engine power and torque are faithfully and efficiently transferred to the
road surface for maximum performance.
The active torque split AWD system uses real-time data input on steering angle, yaw rate,
lateral G-force and engine status to determine road surface and driving conditions. The CX7’
s onboard computer then automatically determines which of three different modes of
front/rear torque distribution should be engaged: Normal, Sport, or Snow (for slippery
surfaces). The active torque coupling mounted in front of the rear differential is
electronically controlled in accordance with the data provided by the computer, adjusting
front/rear wheel torque distribution between 100:0 and 50:50 to deliver optimum drive
power to each axle. The result is that the most power and traction are made available under
all conditions; positive acceleration and confident handling are provided regardless of
constantly changing road conditions, as well as the ability to fully balance the vehicle in a
turn by skilful use of the accelerator pedal.
Unlike many competitor offerings, the torque transfer system in the CX-7 seamlessly
integrates the inherent stability of all-wheel drive; because the active torque coupling is
controlled electronically, it can react to wheel slippage much more rapidly than conventional
gear- or fluid-controlled systems. To ensure consistent power delivery under all weather and
driving conditions, the Power Take-Off (PTO) system on the centre differential that
distributes torque to the rear axle is fitted with its own liquid-cooled cooling system. "

Once the computer has shifted into snow or sport mode it pre-loads the rear axle so you don't have to wait for slippage. As oppossed to the system in the 01-04 Tribute where the wheels had to actually slip before the AWD kicked in.



For those debating the TCS system here is the blurb from the manual on that:

"The braking system works in synergy with the CX-7’s Dynamic Stability Control (DSC),
incorporating a traction control system (TCS), to exhibit an outstanding level of active
safety. The Dynamic Stability Control system is designed to activate when the vehicle is
taking a turn too quickly for the road conditions. DSC compares the driver's intended
direction (from the steering wheel angle) to the actual vehicle path; if the system senses
understeer or oversteer, it applies braking force, and reduces engine torque if required, to
correct the situation.
Traction control systems generally come in one of two primary systems: an ABS-based
system, or an engine management system. Both systems use the ABS wheel speed sensors
to determine if there is wheel spin (wheel speed greater than vehicle speed). The CX-7
system uses engine management to reduce the amount of power output by reducing fuel,
ignition timing and throttle position to reduce wheel spin. This system is superior to systems
that use the ABS brakes to slow down the spinning wheel – ABS systems have a tendency
to be very jarring in their operation and can overheat the brakes if used for extended
periods of time.

The CX-7’s traction control system (TCS) deals with the problem of the
engine supplying too much power for road conditions right at the source; when wheel spin is
detected, the TCS simply reduces the engine’s power output until the wheel spin stops.

I hope, sincerely, the above paragraph isn't true, otherwise CX-7 owers are likely to spend a lot of time with TCS disabled. If only one wheel is "stuck", freely "spinning", the only solution is to apply braking to that one wheel ("virtual" LSD functionality) in order to sustain a high level of engine torque to drive the vehicle via the wheels remaining with traction. And yes, the engine MUST also be dethrottled simultaneously.

I would be VERY surprised if the above is the entire TCS "story".

Modern day vehicles almost all make use of TCS to provide some level of LSD, "virtual" LSD to be sure, but just the same....

The way TCS on the F/awd CX-7 SHOULD work.

If wheelspin/slip is detected and the awd system is NOT fully engaged then TCS should command full awd engagement FIRST. If wheelspin/slip still persists the question becomes, one front wheel or both?

With only one front wheel having lost traction the obvious solution is to apply braking, moderately so, to only the slipping wheel ("virtual" LSD functionality) in order to maintain engine torque to a high level. Also obvious, the engine MUST be simultaneously dethrottled in order to help alleviate the high potential for loss of directional control resulting from loss of traction at the front.

In many commonplace wintertime conditions the immediate result of this virtual LSD activity, moderate braking of the slipping wheel, will be slipping of the "opposite" wheel in addition.

Should both front wheels lose traction simultaneously the potential for loss of directional becomes quite dire and therefore recovery from this circumstance must be as instant as the manufacturer can provide. Therefore I cannot see a circumstance wherein both front brakes wouldn't be applied while simultaneously dethrottling the engine.

But there remains at least one circumstance wherein Mazda3's explanation of TCS might prevail. Suppose the awd system is fully engaged, or even partially so, and it is both rear wheels that have developed wheelspin/slip due to too much engine torque being used for roadbed conditions. There is some danger, potentially, in the initial use of brakes in this instance. Braking both rear wheels in this instance might very well result in the rear wheelspin/slip quickly "leap-frogging" to the front wheels and that might very well prove disastrous. So it would be very prudent design to dethrottle the engine first and then later, within a few hundred milliseconds, apply braking to the rear wheels should the dethrottling not alleviate the rear wheelspin.

In that case it is perfectly acceptable to first/initially simply dethrottle the engine in an effort to regain traction since loss of directional control in this instance is not directly threatened. On the other hand if rear wheelspin/slip persists and the driver doesn't quickly respond by "feathering" the throttle then within a few hundred milliseconds the brake will be used in addition.

Obviously, again, should it be only one rear wheel slipping then the virtual LSD aspects of TCS will automatically brake the slipping wheel and possibly dethrottle the engine if braking turns out not to be an aid alone or if braking one rear wheel simply results in its opposite number also losing traction.

Hope this helps.

Oh, one more thing.

On some vehicles in certain circumstances TCS will be pre-emptive in dethrottling the engine. Enter a tight turn at low speed while attempting to rapidly accelerate and it is highly likely that TCS will SEVERELY dethrottle the engine almost instantly. It is important note that in this circumstance the awd system CANNOT(***) be fully engaged, perhaps not even partially, due to the potential for driveline windup.

And try a quick/fast launch with the FWD version and with the turbo spooled up and TCS will very likely instantly intervene.

*** It is probable that the awd system will be DISENGAGED automatically when the brakes are applied, when turning tightly, and/or if DSC is active.

A good detailed description of these new F/awd systems can be had at techinfo.toyota.com as they are now used in the new Venza and the 2010 RX350.

 

[Mazda3]

Your post is based on a lot of generalisations and assumptions. There is no real knowledge of the CX-7 awd or TCS in your post. This seems to be consistent of all of your posts here in the short time you graced us with your presence.

 

[wwest]

Your post is based on a lot of generalisations and assumptions. There is no real knowledge of the CX-7 awd or TCS in your post. This seems to be consistent of all of your posts here in the short time you graced us with your presence.

Yes, most of what I wrote was "generalization", information gleamed from INTERNET sites and factory documentation for the Ford Escape, Mercury Mariner, Mazda Tribute and CX-7, and now the Toyota Venza and 2010 RX350, all of which appear to use basically the same F/awd system.

All reinforced by many years of driving experience starting with farm tractors, Ford, farmall, and John Deere, back in the Early fifties. But when it comes to AWD/4WD/4X4 systems it goes back to a WWII jeep we used on the farm, sometimes to serve as a tractor and sometimes just to get down to the Tennessee or Mississippi riverbank for cat-fishing.

But my real experience, adult experience, began with the purchase, and NEED, for a used 1985 Jeep Cherokee Limited in about 1987. That was followed by a new 1992 Jeep Cherokee limited which was retired to the north central MT ranch near the Missouri breaks in 2001 after we purchased our first RX300. The Jeeps had RWD/4WD/4X4 modes and the '92 is still doing STELLAR duty on the ranch.

Our first RX was a F/awd '00 but quickly traded in for an '01 F/awd RX300 to get HID, TC, and VSC. We also have a R/awd '01 Porsche C4 but the awd aspects of that are not worthy of discussion "here".

Over the years we have also gone through a series of R/awd Ford Aerostars, mostly, initially, acquired for family and group ski trips. First was a new '94 AWD Aerostar, followed by a used '92, and now another '94 Ford Aerostar.

So, yes, I do not own an RDX, CX-7, Escape, Mariner, Tribute, Venza, nor a 2010 RX350. Nor even an RXh F/awd. At this moment I would say that the Venza is my most likely my next purchase, but the RX will need to die for some unforeseeable reason first.

Sorry to be so verbose but I felt the need to give you some level of assurance that I just might know something about that which I often discuss "here".

 

[Mazda3]

The CX-7 doesn't have the same AWD system as the Tribute/Escape/Mariner and the RDX is completely different system. The info I posted IS how the AWD works in the CX-7.

Your posts are very long winded, uninformative, misguided, and generally not useful to the CX-7 owners here. I'm recieving complaints from the members and you have apparently been banned from other sites for the same reasons.

 

[wwest]

"...no real knowledge.....CX-7 awd....or TCS..."

Do you also burn books...???

You obviously haven't a CLUE....!!

But, why not, rather than simply being another naysayer, your position "here" warrants a reasoned, well reasoned response.

Like by not only saying wherein my disertation was incorrect, but stepping up and providing the correct information.

Sorry, but I am able to say, truthfully say, I have more real knowledge, knowledge of SOLID foundation, of the CX-7 F/awd system and the Mazda FWD and F/awd TCS system than the clear majority of owners of same.

 

[Mazda3]

I posted how the AWD works. The info I provided is not only correct, but all the detail 95% of the people here require. You opened a can of worms that didn't need opening. The info you provided wasn't required and some of it was wrong. You don't own a CX-7 and aren't buying one, why are you here?

 

[wwest]

The CX-7 doesn't have the same AWD system as the Tribute/Escape/Mariner and the RDX is completely different system.

May I first ask...What is YOUR foundation for making this statement?

Have you bothered to research, read up, on the operation of the Tribute/Escape/Mariner and the RDX (huh,...how did the RDX get in there..Did I goof..I am very, VERY well aware that the RDX uses the SH-AWD system, a STELLAR AWD system in comparison to most FWD based awd systems.) If I actually said RDX I most probably meant to say RX350 (and venza)

The info I posted IS how the AWD works in the CX-7.

I'm quite sure I NEVER said your information was incorrect, mine was simply an expansion of the slightly more meager knowledge you provided.

Your posts are very long winded, uninformative, misguided, and generally not useful to the CX-7 owners here. I'm recieving complaints from the members and you have apparently been banned from other sites for the same reasons.

Yes, the truth often hurts, and it is often that pain that results in true believers, those that will not, do not wish to face the bare truths, that are complaining.

Plus, if TCS operation is as you stated why are so many posters seeking ways to disable same...?? The only reason for wishing to disable TCS would be because it sin't fully fucntional in all circumstances.

Now, while that is certainly true of many other TCS, Traction Control Systems on F/awd vehicles (intentionally excluding FWD) I do not believe it to be true on the CX-7. If the CX-7's combination of F/awd and TCS cannot suffice in ALL circumtances then what you need is more traction, say tire chains, a tow, or maybe an entirely different vehicle. Or maybe just a wintertime driving LEARNERS permit.

There is, really, no substitute for TRACTION. The CX-7 F/awd system has the ability to spread the available engine torque evenly between teh front and rear drivelines. Absent a mechanical rear and/or front LSD TCS is often used to "fill-in" provide a virtual LSD.

If the CX-7 is providing ALL of this capability and you are still stuck then you simply do not have enough traction between the tire surface and the earth.

 

[Mazda3]

My AWD and TCS work fine in all conditions.

Everyone who is tired of wwest's rambling please place him on ignore, stop responding to his posts and he will go away.

 

[SuperStretch18]

Done...

 

[wwest]

I posted how the AWD works. The info I provided is not only correct, but all the detail 95% of the people here require. You opened a can of worms that didn't need opening. The info you provided wasn't required and some of it was wrong. You don't own a CX-7 and aren't buying one, why are you here?

Is there a relatively easy way, paypal say, I could fund you the $10 needed to join techinfo.toyota.com for just one day and thereby enable access for you to read about the Venza and 2010 F/awd system and therefore understand the basis for my saying that those are virtual duplicates of the CX-7 F/awd system..??

After you have read that material and we still disagree I will go silently into the night.

 

[wwest]

I posted how the AWD works. The info I provided is not only correct, but all the detail 95% of the people here require. You opened a can of worms that didn't need opening. The info you provided wasn't required and some of it was wrong. You don't own a CX-7 and aren't buying one, why are you here?

"...but all the detail 95% of the people here require.."

And you know that, HOW...??

Nice to be able to speak for 95% of CX-7 owners and potential owners doing research for eventual purchase.

"..the info you provided wasn't required..."

And that's for you to say.........???!!!

"..and some of it was wrong..."

Not to do me any favors but if I was providing incorrect information don't you think, as a moderator, it might be beneficial to the other forum members to not only point out in detail which parts were incorrect but provide the correct information...??

And finally...

"..and aren't buying one..."

I haven't yet made that decision, yay or nay.

I may yet buy one just to implement the Atkinson cycle for cruising and have it transition in the Miller cycle as boost begins to rise. I would probably also modify the anti-lock system in order to prevent activation absent the actual need as indicated by DSC.

 

[wannabe]

I may yet buy one just to implement the Atkinson cycle for cruising and have it transition in the Miller cycle as boost begins to rise. I would probably also modify the anti-lock system in order to prevent activation absent the actual need as indicated by DSC.

lol. oh, and show me where you found out that the cx-7 uses an atkinson OR miller cycle design? or are you saying you would BUILD it to that??? you should work for mazda then....and let us know how the electric motor design goes...

 

[SpooledupRacing]

lets just say with two modded cars AWD will win in a drag race.. take an EVO IX with the rev box.. watch one of them drop from 5K or so and launch.. it will eat a FWD off the line anytime..