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Throttle opening and kickdown switch

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Old Feb 9, 2020 | 04:06 PM
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Default Throttle opening and kickdown switch

I have read a lot about the kickdown switch on this forum, but still unclear about how it affects the actual throttle opening. I realize it is for urgency/emergency when it comes to auto mode downshifting, but even in manual mode I have seen the acceleration is a lot harder when I "kick through" the kickdown switch. Thing is, I have seen you have to slam the throttle really hard to "kick through" the switch otherwise, if I progressively push the throttle down, it has enough resistance to stop my foot with mild pressure.

Question is, what are the affects of the kickdown switch on the actual throttle opening? If you push the throttle down to the kickdown switch thinking you are full throttle, is it actually open say 80% and you have to push the throttle through the kickdown switch to get full 100%? Is it a placebo effect I am feeling that the acceleration is much harder when I slam the throttle all the way to the floor as opposed to getting blocked by the kickdown switch? Thanks.
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Old Feb 10, 2020 | 08:44 AM
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This issue has been heavily discussed on the IS F forum in multiple threads. Take a look at this thread for a method to make the kickdown switch not noticeable:

https://www.clublexus.com/forums/is-f-2008-2014/521519-little-button-behind-gas-pedal-2.html

https://www.clublexus.com/forums/is-...ml#post9672614 - my impression of the kickdown switch in the GS F after driving the modified IS F and GS F back to back.

Last edited by lobuxracer; Feb 10, 2020 at 08:51 AM.
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Old Feb 10, 2020 | 11:18 AM
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Thanks. I agree with your observation about the stiffness of the kickdown switch. RCF feels similar to what you described about the GSF. It is quite stiff and you have to really commit to wanting to push through the switch. It almost feels like a nanny that was put there by lawyers or something. If I progressively push down, it seems like I have hit the floor, but it is actually the switch blocking the throttle. If I really kick hard then it goes all the way to the floor and the car launches forward with a lot of wheel spin. If I had not known about the kickdown switch, probably I would be thinking it is full throttle when it is actually not.
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Old Feb 10, 2020 | 05:58 PM
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Nerdy tech stuff, I love it. I've been calling it the "but wait, there's more" button.
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Old Feb 11, 2020 | 04:45 AM
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I took care of that stiff switch on my RCF. Here are some pictures I took when I did it.







Taken apart.


Showing 3 springs after cutting.


Last edited by JT2MA71; Feb 11, 2020 at 04:54 AM.
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Old Feb 11, 2020 | 10:20 AM
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Looks very familiar to me.
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Old Feb 11, 2020 | 12:16 PM
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Nice pictures. My biggest complaint about it is, you can roll into the throttle especially coming out of a turn past the kickdown switch since it requires so much pedal pressure to get past it, your foot slams to the floor and suddenly you have 100% throttle.
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Old Feb 14, 2020 | 11:22 AM
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Question

Originally Posted by lobuxracer
https://www.clublexus.com/forums/is-...ml#post9672614 -
my impression of the kickdown switch in the GS F after driving the modified IS F and GS F back to back.
Originally Posted by lobuxracer
I've been driving them back to back for a couple of weeks now. Issue #1 - the kickdown switch in the GSF is too stiff and artificially limits WOT. I chopped the springs in my ISF's kickdown switch and it is no longer noticeable when I go WOT. I think I need to do the same thing to the GSF to be fair. Issue #2 - the GSF seems so much more gentlemanly than the ISF. My ISF throws me back in the seat with an attitude while the GSF squeezes me back. It's just not the same, but both cars leave the average driver in the average car totally for dead. Issue #3 - I am still sorting out all the options on the GSF, and just today I figured out the mirrors will not do stupid things in reverse if you pair the key with the personalized settings. I've bee suffering because I normally set my mirrors to zero overlap, and the damned things go crazy wide if you don't have a key paired to the seating preset. The ISF does not do this. Pissed me off to no end at first because I always back into my garage, and more often than not, back into parking spaces to ensure I don't scuff the carbon fiber nose (OK, I do the same thing with my ISF too).
Curious... What is your solution for the GSF then?


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Old Feb 14, 2020 | 12:29 PM
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Originally Posted by finny76
Curious... What is your solution for the GSF then?
Nothing. It's the wife's car, and she could use some resistance to going WOT. If it were mine, I'd do the same thing I did to my IS F - cut the springs.
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Old Feb 14, 2020 | 06:25 PM
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JT2, how is this thing attached to the car? I see no screws through the 3 holes on the flange in the top picture, or you already removed the screws before taking the picture?
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Old Feb 14, 2020 | 07:04 PM
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I wonder if it has nothing to do with the throttle open % and activates some type of fuel enrichment in the ECU.
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Old Feb 14, 2020 | 07:16 PM
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Originally Posted by buister
JT2, how is this thing attached to the car? I see no screws through the 3 holes on the flange in the top picture, or you already removed the screws before taking the picture?
Yes, the bolts were already removed in the first picture.
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Old Feb 14, 2020 | 08:31 PM
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Originally Posted by CinFulxgs
I wonder if it has nothing to do with the throttle open % and activates some type of fuel enrichment in the ECU.
No, I am quite sure it is tied to opening of the throttle body (someone correct me). The kickdown switch limits 80% (or thereabouts) throttle opening and then when you apply pedal pressure and trip the swtich slamming to the floor, you get 100% throttle. It annoys the hell out of me that I cannot gradually roll into the throttle 70%, 80%, 90% and then 100%. Basically it is suddenly 100% after 80%. Also, I wonder how many people thought 80% was 100% because the pedal stops LOL.
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Old Feb 15, 2020 | 11:40 AM
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Originally Posted by 05RollaXRS
No, I am quite sure it is tied to opening of the throttle body (someone correct me). The kickdown switch limits 80% (or thereabouts) throttle opening and then when you apply pedal pressure and trip the swtich slamming to the floor, you get 100% throttle. It annoys the hell out of me that I cannot gradually roll into the throttle 70%, 80%, 90% and then 100%. Basically it is suddenly 100% after 80%. Also, I wonder how many people thought 80% was 100% because the pedal stops LOL.
100% on point. This is exactly what happens.
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Old Feb 15, 2020 | 03:37 PM
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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.
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