Hesitation Solution, Maybe!

[wwest]

2004 RX330 electrical wiring diagram Pub. No. EWD563U page 177.

(Quote)

"4. Mutual System Control

To efficiently operate the VSC system at its optimal level, the VSC system and other control systems are mutually controlled while the VSC system is being operated.

Engine Throttle control.

The engine power does not interfere with the VSC brake control by controlling the opening of the throttle and reducing the engine output.

Engine control and electronically controlled transmission control.

The strong braking force does not interfere with the braking force control of the VSC system by turning off the accel. and reducing changes in the driving torque at shift-down."

(End quote)

As one can readily see from the above statements the inadvertent operation of the VSC system can result in engine dethrottling and delayed downshifts.

If the VSC detects over-stearing it will apply, modulate, the brakes on the outer turning wheels. The greater the degree of over-stearing the harder that outer front wheel will be braked.

On the detection of under-stearing it will apply both rear brakes (RX330 only??) while controlling engine power.

Notes:

"The engine power does not interfere with the VSC brake control by controlling the opening of the throttle and reducing the engine output."

Take notice that this statement does not necessarily mean that engine power is reduced to idle. It may mean that engine power is "set" to match road speed, no acceleration torque nor any compression braking.

"The strong braking force does not interfere with the braking force of the VSC system by turning off the accel...."

...turning off the accel....

I take it this means opening the firmware control loop between the gas pedal (accelerator) and the throttle valve.

Therefore I take this to mean, again, that the engine throttle control is taken over by VSC to prevent any significant level of engine compression braking.

"...and reducing changes in the driving torque at shift-down..."

Wouldn't this mean delaying down-shifts until the VSC ceases operation?

Since for most of the vehicles exhibiting the hesitation/delay the "outer turning wheel" is also one of the two driven wheels, or as a minimum for AWD one of the two primary drive wheels it is no surprise.

I think we already know that the VSC system firmware has a proactive mode wherein it dethrottles the engine to alleviate the potential for rollovers in an accelerating and/or tight turn.

So, what might make it, the VSC system, think it needs to "operate" just before coming to a full stop or just as you decide to downshift for acceleration.

An unequal rotation rate at the driven, front, wheels versus the rear, that's what!

Would those of you experiencing this problem please, if you don't mind, check and be sure all of your tires are equally inflated. Maybe even a pound or two extra in the front since the majority of the weight is there?

Remember that if you adjust the pressure you will need to "normalize" the new tire pressure levels.

[John_D33]

I know this is 2 plus years later nd I have been living witht h ehesitation in my 06 RX330 for longer than that, but ths really makes sense. Mine is worst whrn I am "rollling" to the accelerating throught a stop making a right turn.

And yes, a bit mor air where the weight is greater would make the tire diameters closer in size.

Thanks,

John