I just bought a 2004 model

I understand the car equipped with three open differentials while wheel slip is controlled by an ABS/TC system - the original viscous central LSD was dropped, likely to save money (and maybe reliability issues as I have been reading...).

There is all variety of traction control system that have been developed around, operating in different ways. Some even go to suppress or retard spark http://en.wikipedia.org/wiki/Traction_control_system

Do you know how the X-Type TC system work? Is it just a basic system detecting a spinning wheel and selectively applying brakes on it, or there is more? or...less? someone told me it only acts on the rear wheels but I believe it is unlikely to be true (it would make the ABS/TC system more complicated). Just to make it clear, I am talking about traction control, not Dynamic Stability Control here...

Incidentally, as I have been reading some of the old threads concerning the failures of the transfer case in the earlier model, I noticed some have suggested swapping the failed unit with a 2004+ one. Since the pre-2004 models have no Traction Control, you would then obviously end up with no wheel spin control at all.

Thanks.

- Sandro

P.S. question to the administrators: why I cannot upload attachments? The "manage attachment" window does not appear on my screen... Thanks

 

Hold on...

I just read in another post from "jimmy" - who sounds very knowledgeable - that all the X-Type models have Traction Control.

So, what I said earlier - about replacing the viscous coupler transfer case (pre-2004) with an open one - may not be accurate...

Sorry for the confusion... I am new here and just trying to learn fast...

- Sandro

 

Sandro, these following paragraphs were pulled directly from the JTIS CD, so, this is coming straight from JAG:

02-03 models (to include early 04 cars):

Dynamic stability control (DSC) maximises vehicle stability under all conditions. The DSC system compares actual vehicle course to that intended by the driver. If the intended course differs from the actual course due to over steer or under steer conditions, the DSC system will brake individual wheels and reduce engine torque to bring the vehicle back to the driver's intended direction. By using a combined yaw rate sensor and lateral accelerometer, the vehicles rotational motion around its vertical axis and centrifugal forces generated while cornering are calculated to determine the vehicle's actual behavior. Using additional sensors for detecting steering wheel position and road wheel speed enables the system to recognize the driver's intentions.

On 2.0L vehicles the traction control system (TCS) is incorporated into the anti-lock brake system (ABS). On 2.5 and 3.0L vehicles the traction control is an additional function added to the DSC system. The vehicles driven wheels are continually monitored for wheel spin relative to the calculated reference speed and to each other. If wheel spin is detected, the traction control function intervenes independently of the driver, applying brake pressure to the slipping wheel and reducing the engine drive torque supply. Meanwhile, brake pressure is modulated by the traction control until traction is re-established. Traction control brake actuation is diminished above 25 mph. Above this speed traction control relies primarily on engine torque reduction.

Mid 04-08:
Dynamic stability control (DSC) maximises vehicle stability under all conditions. The DSC system compares actual vehicle course to that intended by the driver. If the intended course differs from the actual course due to over steer or under steer conditions, the DSC system will brake individual wheels and reduce engine torque to bring the vehicle back to the driver's intended direction. By using a combined yaw rate sensor and lateral accelerometer, the vehicles rotational motion around its vertical axis and centrifugal forces generated while cornering are calculated to determine the vehicle's actual behavior. Using additional sensors for detecting steering wheel position and road wheel speed enables the system to recognize the driver's intentions.

The DSC system also incorporates emergency brake assist (EBA), which measures the rate at which the brake pressure increases during a braking manoeuvre. If the system detects an emergency braking situation, EBA automatically initiates the full braking effect. This can reduce the stoping distances in critical situations, therefore allowing an inexperienced driver to stop in the same distance as an experienced driver.

On 2.0L vehicles the traction control system (TCS) is incorporated into the anti-lock brake system (ABS). On 2.5 and 3.0L vehicles the traction control is an additional function added to the DSC system. The vehicles driven wheels are continually monitored for wheel spin relative to the calculated reference speed and to each other. If wheel spin is detected, the traction control function intervenes independently of the driver, applying brake pressure to the slipping wheel and reducing the engine drive torque supply. Meanwhile, brake pressure is modulated by the traction control until traction is re-established. Traction control brake actuation is diminished above 40 kph (25 mph). Above this speed traction control relies primarily on engine torque reduction.

Hope this gives you the info that you are after in explaining how the two systems, while very similar, are different.

 

Thank you for the information Chris.

Mmmm, this is puzzling though...

I have to make a relevant premise here...I just bought the car but don't have it yet... So I am relying more on the specs/features listed by the seller rather than direct knowledge. Having said that:

1. She is a 2004 2.5 L manual

2. I believe she does not have DSC but only TC

According to the JTIS:

3. "On 2.5 and 3.0L vehicles the traction control is an additional function added to the DSC system."

Clearly, 2. and 3. do not match

4. I am also wondering about "...reducing the engine drive torque supply..." Do these cars have throttle-by-the-wire control? If not, how is the torque reduced? Pulling timing? Cutting sparks?

5. Finally, the JTIS information does repeat the same even for pre-2004 cars (those equipped with central viscous couple inside the transfer case) that the TC is incorporated into the DSC. What about those without DSC?

I know these questions may sound academic. It's just that I like to know how things work (in general)...plus I am now rushing to learn more about these cars (while waiting for mine to be delivered) - I guess you can understand...

Thanks

- Sandro

 

Sandro, yes, our cars are drive by wire. So, the computer can limit the torque even though you are hard on the gas.

It is easy to see if your car has DSC or not. On the center console, you should have a button marked "DSC". No button, you don't have the feature.

 

Thanks Chris.

Drive by wire then.

As for the DSC, I will have to wait getting the car first to check it definitely.

For now, I am relying on the seller (TexasDirectAuto) listing, which says TC but does not explicitly lists DSC. TexasDirect Auto listings are generally very accurate. If the car has indeed DSC it will be a nice plus.

- Sandro

 

Sandro, I went back to your other post with the E-Bay link showing the car. Although you can't quite tell from the pictures, it DOES look like you have. Hope you do!. Let us know how happy your are with the car when you get it.


It sounds like you did not actually go there and see the car before buying it. Just curious, how does that work if when the car is delivered you see things that are not correct or not exactly as described? What if you are not satisfied? The internet has changed how people buy cars, but I guess for me I would have a hard time buying something like that by pictures. I found mine on the internet, but flew down 500 miles to look at it before signing anything. There were a couple things that I needed ironed out before I drove it away. Hope everyuthing works out for you.

 

Thanks for looking into it!

I bought a 8.1 L (a quite rare "marine" engine) 2005 Suburban from TexasDirectAuto two years ago, which I have been happily using to trail around my Rx7 autox car.

It has been a very satisfying experience and I trust their model, which they pioneered. They have $200 M in sale now and 100% satisfaction feedback.

1. They pre-screen vehicles and only sell those in top conditions.
2. Quite meticulous description and detailed listing
3. 3-mo limited but quite extensive warranty
4. You can return the car within 3-day of delivery if you don't like it (but have to pay for sending it back)
5. Reasonable pricing v. local market
6. 100% customer satisfaction based on a very broad statistical base

In the end, you are buying a "commodity" not a custom piece.
Although I have a quite good cars knowledge (mostly from working on, modifying and tuning by myself my twin-turbo Rx7), I do not think I would be able getting any better judgment just by looking at a car in person or test driving it - other than obvious flaws of course...
I trust better a specialized company, equipped with the technical and commercial tools to screen the car they sell, a pristine track record and reputation.

There are also some practical reasons: I could not find a good example locally for a reasonable price, and I did not to wait for the "right one" to show up. Sure, I would have preferred a 3.0 manual and perhaps with the mechanical LSD (I used to have a very sure footed Subaru with the viscous coupling in the past) rather than relying on the ABS to brake spinning wheels... but overall I find this model very satisfactory for the price. A stiff platform and quite an advanced engine and engine management for what I know so far. I am looking forward to learning more...JTIS CD is on its way to be delivered and then devoured.

- Sandro

 

So... car is in and definitely does not have DSC - only a slotted cover where the DSC switch should be.

Car is 2004 2.5 L

So, if I now read again the JTIS with Boolean eyes

either

1. the JTIS is wrong and I still have traction control (like the 2.0 liter - not a US model)

or

2. I may have a car with three open diff and no intrinsic mechanisms for slowing down a spinning wheel...

I hope is 1.

- Sandro