Pwr Button

[LexusForever]

I may be dumb, but i can't for the life of me figure out what purpose the PWR button has in my Auto SE??? the car reacts exactly the same whether i have it turned on or not. i was expecting it to unleash the vvti much earlier or something to improve performance, but there is no difference whatsoever! when i use the snow button there is an obvious change in the engine and performance, so why not with the PWR button?

Can someone enlighten me?

[Rikos]

You say that you where hoping it released the vvti earlier but the vvti i is always working. It's not like a sc or turbo it doesnt have a kick in point. vvti is designed to optimise valve performance by using less valves in the lower rev range to maximise performance and then using the 24 valves at the higher end of the rev range.

I have no idea what the power button does though as i have the manual.

[LexusForever]

but then why does it take off like a rocket at 4500rpm? below that my mother could walk faster, but the second it hits 4500 all hell breaks loose and away you go, kinda like my fiat turbo used to?

geeez i'm so confused!!!!

[derekyau]

What you should notice is the sharper throttle response - the gear's eagerness to kick down a lot sooner than you would normally be used to. Slightly more of a stiff neck syndrome due to the slightly harsher aceleration on your drive.

D.

[LexusForever]

Ahh. thanks. i will check it out on the way home :)

[Rob]

You say that you where hoping it released the vvti earlier but the vvti i is always working. It's not like a sc or turbo it doesnt have a kick in point. vvti is designed to optimise valve performance by using less valves in the lower rev range to maximise performance and then using the 24 valves at the higher end of the rev range.

I have no idea what the power button does though as i have the manual.

it always uses 24 valves - there is no "disconnect mechanism" for the valves VVTI is Variable Valve Timing with Inteligence all it does is vary the valve timing to achieve better performance.

[LexusForever]

thanks for that. next question - is there a way of reprogramming it so that if you press the pwr button it sets the timing to the max performance no matter what the revs? in other words instead of taking of from 4500 it takes off from stand still?

feel free to tell me if i'm being an idiot - i'm just learning about all this stuff. usually to me if the car starts it's working, if not call the AA. i only open the bonnet to fill the washer or clean the engine bay, couldn't tell you what anything in there does if my life depended on it.

i suppose i should really do some work but this site is becoming addictive!!!

[Rob]

you can if you really really wanted to... there is a unit available to do that but have no idea of cost or whats invloved with the setting up. I dont think anyone has had it fitted tho

[LexusForever]

thanks mate, might look into it.

[Rob]

I think dave at prolex can get the units???

[tyrrp]

thanks mate, might look into it.

I used to have an old style (gen 2) Honda CRX imported from Japan. It was a VTEC which was the start of all the variable valve timing stuff. It had a VTEC Controller installed. You could set the revs at which the timing changed anywhere from 500rpm to 7000rpm. It was very handy. Must say, that was the most fun car I ever owned. Unfortunately became the car of choice for drug dealers over here so it had to go. I do miss it though.

[Rob]

vtec is totally different from vvti

[Lexxy_703]

definitely notice the difference in my IS300 when PWR button on, very handy for a swift take off at a busy roundabout! :D

[MacRS200]

vtec is totally different from vvti

Welcome to LOC Rob

As Rob says the systems are different, VTEC changes the cam profile at a set RPM. VVTi changes the position of the drive pulley relative to the cam shaft enabling the valve timing to be advanced or retarded, it does not change valve lift or dwell times like VTEC does.

In answer to the question about about changing the valve timing, it can be done with a "piggy back" controller such as the CamCon (which is probably the lowest cost option), without any other mods I really don't think it would make much difference though.

[kingy58]

definitely notice the difference in my IS300 when PWR button on, very handy for a swift take off at a busy roundabout! :D

Me too in my IS300 Sportcross there's a definite difference when pulling away and also car stays in lower gear longer before changing up giving better accelleration.

[tyrrp]

vtec is totally different from vvti

Never said it was the same. Just said it was the start of the variable timing. VTEC actually slides the cam shaft so there are different cams acting on the valves making them stay open longer etc. Much more of an ON or OFF system then VVT but still lots of fun and probably more designed for performance then the VVT systems.

Remember that Honda were the first to get over 100bhp per litre from a normally aspirated engine with the VTEC system.

[MacRS200]

vtec is totally different from vvti

Never said it was the same. Just said it was the start of the variable timing. VTEC actually slides the cam shaft so there are different cams acting on the valves making them stay open longer etc. Much more of an ON or OFF system then VVT but still lots of fun and probably more designed for performance then the VVT systems.

Remember that Honda were the first to get over 100bhp per litre from a normally aspirated engine with the VTEC system.

It actually uses oil pressure to push a roller into the cam lobe to change the profile and increase lift. Sure I read that somewhere

edit - both wrong as it happens, here is a short VIDEO showing how it works :D

Edited September 4, 2007 by MacRS200

[swfcdan]

but then why does it take off like a rocket at 4500rpm? below that my mother could walk faster, but the second it hits 4500 all hell breaks loose and away you go, kinda like my fiat turbo used to?

geeez i'm so confused!!!!

love the description

[tyrrp]

vtec is totally different from vvti

Never said it was the same. Just said it was the start of the variable timing. VTEC actually slides the cam shaft so there are different cams acting on the valves making them stay open longer etc. Much more of an ON or OFF system then VVT but still lots of fun and probably more designed for performance then the VVT systems.

Remember that Honda were the first to get over 100bhp per litre from a normally aspirated engine with the VTEC system.

It actually uses oil pressure to push a roller into the cam lobe to change the profile and increase lift. Sure I read that somewhere

edit - both wrong as it happens, here is a short VIDEO showing how it works :D

Doh! That's right I remember it being explained to me properly now. It's a different rocker that's engaged.

[LexusForever]

but then why does it take off like a rocket at 4500rpm? below that my mother could walk faster, but the second it hits 4500 all hell breaks loose and away you go, kinda like my fiat turbo used to?

geeez i'm so confused!!!!

love the description

thanks. comes from trying to be a motoring journalist like jeremy clarkson when i was a teenager : got published once and they edited out all my witty comments :tsktsk: the witty comments were the only thing worth reading about a Ssangyong Musso!!!!

[Bazza]

the power button simply raises the revs before it changes gear :D

nought to do with vvti or vtec or any other v thingys

[MacRS200]

the power button simply raises the revs before it changes gear :D

nought to do with vvti or vtec or any other v thingys

what about v-power Bazza, you will use a bit more of that

[LexusForever]

this was my initial confusion, because i don't see the point in that. if i press the power button it means i'm a second away from planting the accelerator through into the engine compartment and if i do that with the button switched on or off, it makes no difference, the engine will go to the red line before changing.

what i really want it to do is give me the power boost that comes in at 4500rpm, much lower in the revs range so that when i am at junctions, roundabouts, or when the urge overwhelms me, i can boot it without having to leave a gap waiting for the revs to build up. it's almost as if she has to brace herself and take a deep breath first!

from what i'm told the camcon? is the way to go. i see pro-lex do one and i am going to contact them about it when the dosh flow has grown a little.

[w481ggc]

All the power button dose is hold the revs to about 6500 then changes up provided you keep the pedal floored :)

[MacRS200]

It also sets the change down higher up the rev range so it changes down earlier when you floor it to keep in the "power band".