Help!!!??????

[oab_au]

Originally posted by Beav
One thing to remember/consider Harvey: the TCU will throw as much torque to the rear as posible each time the car is accelerated from a standing start, in order to thwart torque steer.

Hi mate, Yes it does apply pressure at blast off, but does the transfer valve move as far as it does when the front wheels actually spin. Then max pressure is applied and the valve has max travel, into areas not used for some time.

Have you pulled down a failed valve to see what the cause was?


Harvey.

[Beav]

Originally posted by oab_au


Hi mate, Yes it does apply pressure at blast off, but does the transfer valve move as far as it does when the front wheels actually spin. Then max pressure is applied and the valve has max travel, into areas not used for some time.

Have you pulled down a failed valve to see what the cause was?


Harvey.

I guess I'm lucky enough to have avoided that pleasure so far.
However, if I recall prorperly, I read somewhere that it was supposed to go full apply at launch. It has been my experience on other cars that duty solenoids go belly-up from sheer wear, due to the nature of their operation. Of course, contamination is always a huge possibility too.

[oab_au]

Originally posted by Beav


I guess I'm lucky enough to have avoided that pleasure so far.
However, if I recall prorperly, I read somewhere that it was supposed to go full apply at launch. It has been my experience on other cars that duty solenoids go belly-up from sheer wear, due to the nature of their operation. Of course, contamination is always a huge possibility too.

Yes the DRW site said that the solenoids fail mechanically, as you would expect from the number of cycles in their life. Though it seems strange that this time, it happens when Roger8519 has a wheel spinning snow run.

Harvey

Wait, the power is supposed to be transfered to the rear wheels at launch? Whenever it is wet and I floor it my front two tires will spin freely (bald tires) for about a full second to a second and a half before more power gets shoved to the back. Is this normal?

[oab_au]

Originally posted by AbdominalSnoman
Wait, the power is supposed to be transfered to the rear wheels at launch? Whenever it is wet and I floor it my front two tires will spin freely (bald tires) for about a full second to a second and a half before more power gets shoved to the back. Is this normal?

No Snoman, That's not normal. The TCU will apply torque to the back wheels based on two premises. First it will apply torque in line with the program, that is written in it's AWD map. This depends on the gear selected and the throttle position, The lower the gear, the more throttle, the more torque applied to the rear. So the TCU pre-empts wheel spin and the need for rear drive.

The other way it responds, is to a difference in the front to rear wheel speed. A small amount means the car is turning a corner, so a small amount of rear torque is applied. If the difference is large, (over 20%), the TCU will react by applying full torque to the rear wheels , this should be almost instantaneous and there should be no noticeable front wheel spin.

If the front wheels do spin, as you say "for a second or so" there is a delay in the take up. This delay is not good as when the clutch takes up the front plates are already spinning faster than the rear clutch plates. This causes the clutch to act as a brake to slow the front wheels down to the back wheel speed. As you would realise this causes a lot of clutch plate wear.

If everything is working right, the clutch never has to apply with plates spinning at difference speeds, as it will allways apply pressure before it gets to that state.

What would cause the delay? A slow acting C Solenoid? may be. Worn clutch plates? may be. Slow acting or sticky transfer valve? This would be my guess.

Harvey.

[svx_commuter]

Originally posted by AbdominalSnoman
Wait, the power is supposed to be transfered to the rear wheels at launch? Whenever it is wet and I floor it my front two tires will spin freely (bald tires) for about a full second to a second and a half before more power gets shoved to the back. Is this normal?

I had no rear wheel drive and turned out to be a bad C transfer valve assembly. It did not give any codes on the computer. The easy way to find out i sget all four wheel off the ground and see if the rears have power. It is important to get this checked because you can wear out the front dif if no power is going to the rear. That does depend on how you drive. Fast starts will over overload the front dif when the rear isn't working.

That may explain why about 6 thousand miles ago my front differential gears completely shattered into several pieces forcing me to rebuild the tranny before its time was due. I'll get this checked out as soon as I can. I'll also research how to get all the codes out of the ecu, tcu and any other ?cu that can give me any.