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It's kinda like a double barrel carburator. I used tweak mine, so the second carb would open a little sooner.
That's a crap shoot. Velocity is key to success and a lot of why the OEMs went to vacuum operated secondaries. If you give an engine too much throttle, velocity drops like a rock and the carburetor loses the Bernoulli battle - it fuel starves. Ask anyone who ran big "smoothbores" on a bike engine and whacked the throttle open at low rpm only to have the engine stall completely.
In this case, nothing bad is going to happen if you alter the springs unless the kickdown switch remains on all the time. When that happens, the ECM ignores the kickdown switch entirely and you lose normal downshift ability in D mode.
^^^^Back in the 70s I ran Holly Spread Bore Double Pump carbs in my GTOs and then a TA. I could feel the detent in the pedal when the secondaries were about open. When they opened and the second pumped squirted fuel into the secondaries, it was hold on No vacuum secondaries for me, double pump was the way to go.
This GSF owner made a video about it just recently showing the kickdown switch. He credited just recently having found out about it on clublexus about unleashing the extra HP. Makes me think it must be my thread that raised awareness about it.
I'm curious now if the claimed 0-60 and 1/4 mile times were based on this 100% throttle input? Anybody with a dragy able to do a test?
Yeah, that is a good question. A lot of people have no clue about it. It is anyone's guess how hard the throttle was being pushed down by the tester. Agreed someone at sea level should do a test using a cellphone app.
I believe that is what post #5 is showing where the switch is being disabled.
No, it isn't. It's showing how to reduce the pressure required to actuate the switch. If you disable/bypass/set permanently on/off, the ECM will ignore this input and not kickdown hard when you go WOT. This is well documented by Lexus.
No, it isn't. It's showing how to reduce the pressure required to actuate the switch. If you disable/bypass/set permanently on/off, the ECM will ignore this input and not kickdown hard when you go WOT. This is well documented by Lexus.
List price is $113.43. The Bay has them much cheaper. They're only rarely damaged in an accident and they're used on 2IS, 3IS, GS since2005, and all RC platforms, so they're pretty cheap used.
Based on this thread I wanted to do some tests about the claim that the car doesn't go full throttle unless the kick down switch is pressed. I wanted to know if it was just a placebo effect. So I connected up my OBD2 scanner and monitored the relation between accelerator position and throttle opening.
My conclusion is the switch only affects transmission control, it really only kicks the transmission down to lower gears, giving you harder acceleration. Did a few 60 mph pulls, full throttle dropped from 8 to 4th gear, full throttle pressing the kick down dropped to 3rd gear. Obviously the 3rd gear pull was "stronger."
Screen shots are below, first two are accelerator stopping at kick down switch, next two are pressing the switch. The car reads this as ~90% vs 100% - however the actual throttle opening is EXACTLY the same in either scenario.
For that to happen, it would mean the last few inches of the throttle pedal travel past the kickdown switch does not yield more throttle opening? Essentially, it is 100% throttle opening before the kickdown switch? I am skeptical of that. I drive only in manual mode and don't know, but I do feel a "surge" after tripping the kickdown switch and flooring it all the way down to the floor board.
For that to happen, it would mean the last few inches of the throttle pedal travel past the kickdown switch does not yield more throttle opening? Essentially, it is 100% throttle opening before the kickdown switch? I am skeptical of that. I drive only in manual mode and don't know, but I do feel a "surge" after tripping the kickdown switch and flooring it all the way down to the floor board.
yup, it's 100% throttle opening before the switch. There might be load or timing differences, but my test proves the throttle position isn't affected by a transmission kick down switch.
yup, it's 100% throttle opening before the switch. There might be load or timing differences, but my test proves the throttle position isn't affected by a transmission kick down switch.
No vacuum secondaries for me, double pump was the way to go.
