Overtaking Performance at High Speed

[KWAWD]

Question for the AWD owners about overtaking.

When going to overtake at high speed (aprox 100 kms) when I put my foot down the auto will kick down what feels like a couple of gears (so to 3rd?) causing the RPM to then rapidly increase to near redline (6000 rpm). The actual speed pickup is slow and not very satisfactory. The engine RPM is screaming at me for little benefit and I have to back-off so it will upshift. Is this typical? The car accelerates fine at lower speeds.

I know these arent performance cars, but I hate this behavior, I'd rather it kicked down 1 gear only, to avoid all this fuss and rev noise. So could it be driver error, am I just being too heavy footed?

(Once again, my KH experience is completely different. Sometimes it won't kick down at all, which can be annoying, but when it does it never redlines like that and is quite smooth and quick to overtake.)

[munkeymanz]

I'd say use tippy to either hold 5th or select 4th. Best solution though is to fit a 6G75 motor. I find the 3.8 much better at overtaking in 5th than the 3.5 overtaking in 3rd or 4th! Not to mention if it shifts back.

[MadMax]

Most auto boxes have that problem, kicking down too far in the gears and revving the pants off the engine without speeding up.

As above, plant the foot and pull back one gear in tippy mode.

6,000 rpm at 100 kph - does that sound like second or third gear for the 5 speed? What are the speeds at 6,000 rpm through the gears on the 4 and 5 speed boxes anyway?

I've noticed the tippy gearbox will downshift by itself as you slow down, but you have to upshift manually as you speed up. Does the tippy function lock out the kickdown function when you plant it at speed?

[GTVi]

Too avoid this behavour on an open road, I normally take a "run up" so that I reach overtaking speed before I approach the vehicle, and then pass without having to change down. But what you described is normal, that's why I would use the tippy if I needed to.

[vlad]

6000rpm is way past usable torque hence not much acceleration. You have an AWD which has the 5sp tippy. Just shift across and down once which will be in 4th and around the 4000rpm range which is where the peak torque is at. Mind you, with the 380 cams, I noticed that it can happily accelerate up incline in fifth where before I had to change down a gear.

[KWAWD]

Thanks guys, this is just driver error then. I'll try out the tiptronic - havent really played much with that since getting the car. Will be a bit of an adjustment for me after all these years!

Does the tippy function lock out the kickdown function when you plant it at speed?

Hmm, i sure hope so. I'll try this over the weekend.

[vlad]

Thanks guys, this is just driver error then. I'll try out the tiptronic - havent really played much with that since getting the car. Will be a bit of an adjustment for me after all these years!


Hmm, i sure hope so. I'll try this over the weekend.

To answer MadMax's question, yes. I always drive in tippy mode and the few times when I forgot to downchange, it did not kick down.

[MadMax]

To answer MadMax's question, yes. I always drive in tippy mode and the few times when I forgot to downchange, it did not kick down.

Good to know. Fresh to the tippy bit myself, haven't had much of a chance to play with it.

[SH00T]

A tippy will hold the gear you are in, unless you slow below the allowed speed in the ECU....

[WytWun]

When going to overtake at high speed (aprox 100 kms) when I put my foot down the auto will kick down what feels like a couple of gears (so to 3rd?) causing the RPM to then rapidly increase to near redline (6000 rpm). The actual speed pickup is slow and not very satisfactory. The engine RPM is screaming at me for little benefit and I have to back-off so it will upshift. Is this typical? The car accelerates fine at lower speeds.

I know these arent performance cars, but I hate this behavior, I'd rather it kicked down 1 gear only, to avoid all this fuss and rev noise. So could it be driver error, am I just being too heavy footed?

I know exactly what you mean. As others have said, the tippy downshift gives the best control. At 100kmh, my recollection is that a shift down from 5th to 4th raises revs to around 3000, which is not quite enough for maximum acceleration (needs to be over 3500rpm with a stock engine in my experience). Downshifting to 3rd gets you to a bit over 4000rpm which is close to peak torque.

This is mostly a problem with the shift maps, both up and down, in the ECU. The L/W series AWDs have the most aggressive 5th gear downshift maps of them all (even more aggressive than the Ralliart autos) but the downshifts below that are the same as the TJ AWDs (which are somewhat more aggressive than the FWD 5 speeds and similar to the Ralliarts). However the other problem I found with the stock shift maps is that the WOT upshifts are set for around 5800rpm, which is too far above the top of the power band for the stock cams (though fine with better cams).

The TPS based shift maps are modifiable now (via ECU reflash), however it does take some work to set up a satisfactory shift mapping to cover most situations. tippy still works better though... more grunt (cams, extractors, tune, etc) helps too...

(Once again, my KH experience is completely different. Sometimes it won't kick down at all, which can be annoying, but when it does it never redlines like that and is quite smooth and quick to overtake.)

The stock 4 speed shift maps that I've seen won't downshift from 3rd to 2nd until very slow speeds (30-40kmh).