Want better low end performance, try this! It's free!
12-25-09, 02:21 PM
#151
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I didn't read through every post because there are a lot and I have an sc300 but instead of a toggle switch why don't you wire up a micro switch on the throttle body or find a way to use the tps sensor, to send a signal to a relay wired to the wire being discussed, so when the full throttle signal is sent it will open the wire circut and do what you are wanting and when to let off or go to light throttle the circut is back to normal.
12-25-09, 02:29 PM
#152
I haven't read through this whole thread because it is long as crap and I have an sc300 but I was thinking, why couldn't you wire up a micro switch to the throttle body so when you go full throttle the switch will power a relay and open that wire circut to do what you want and when you let off wot for light driving the circut is good again. Will work the same as a toggle switch, just automatic. And instead of people cutting the wire why not just unpin it.
One could de-pin if they'd rather. IMO, much easier to cut since I don't plan on ever putting it back.
My car is so far gone I don't think at this point it would be possible to return it to stock.
KC
12-25-09, 09:34 PM
#154
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The 4 speed SC400 auto transmission has 4 selonoids that work the shifting that are electricly controled by the ecu. 1 and 2 run the actually shifting ( not sure what 3 does they said something about locking but im not sure).
number 4 has to do with the "smoothness" of a lexus ride. at take off and in between gears this selinoid bleeds off pressure (makes the tranny slip) so that it doesnt snap your neck at launch and is smooth between shifts.
removing the #4 selinoid increases shift responce and makes the car squat at take off.
Although the downshifting is just as ruff (kinda crapy feeling).
To do this mod on the 92-95 sc400 you snip or interupt the wire in pin number 13 on the ecu. its pinkish red with a black stripe.
number 4 has to do with the "smoothness" of a lexus ride. at take off and in between gears this selinoid bleeds off pressure (makes the tranny slip) so that it doesnt snap your neck at launch and is smooth between shifts.
removing the #4 selinoid increases shift responce and makes the car squat at take off.
Although the downshifting is just as ruff (kinda crapy feeling).
To do this mod on the 92-95 sc400 you snip or interupt the wire in pin number 13 on the ecu. its pinkish red with a black stripe.
where is the ecu located on the SC4? I just bought this car 2 weeks ago so I havent really looked around much.
10-05-10, 08:33 AM
#158
10-18-10, 08:24 AM
#160
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Just did this in my '93 SC400, all stock...and HOLY *****! Like night and day off the line... 
The ONLY difference I noticed (other than tq) was a slight "tug" when down shifting into 1st gear when I pulled back in the driveway - does anyone know if this will negatively affect the tranny?
Now I have to go put everything back together on the passenger floor board
Will update after driving a bit more...
The ONLY difference I noticed (other than tq) was a slight "tug" when down shifting into 1st gear when I pulled back in the driveway - does anyone know if this will negatively affect the tranny?
Now I have to go put everything back together on the passenger floor board
Will update after driving a bit more...
10-22-10, 03:28 PM
#161
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After I did this mod, I got more firm shifts, quicker downshifts along with that off the line tq. I was amazed at the difference. Yesterday I tired unplugging the airflow meter along the no 4 plug. DAAAAAAAAAAM, off the line, the car will get sideways each and time I went wide open...only downside i see now is the od light flashes, but other then that, its all good, FOR NOW.
10-22-10, 05:17 PM
#162
I am very surprised to see everyone doing this ridiculous mod.
I dont mean to offend anyone but I mean cutting the wires to your solenoids----messing with the ecu? come on.
Who knows what sort of issues or problems you may be setting yourself up for or what sort of damage you may be doing.
And for what ----a slight boost off the line -----?????
Personally I love my car too much to experiment on it like this---thanks .....but no thanks.
I dont mean to offend anyone but I mean cutting the wires to your solenoids----messing with the ecu? come on.
Who knows what sort of issues or problems you may be setting yourself up for or what sort of damage you may be doing.
And for what ----a slight boost off the line -----?????
Personally I love my car too much to experiment on it like this---thanks .....but no thanks.
10-22-10, 05:29 PM
#163
Wow I just read this entire thread from front to back ------im amazed at all the people that were willing to put their car in jeopardy for this miniscule gain in performance--------
Im actually very disapointed to see it.
Some people are complaining of the tranny slipping and not changing gears properly--after cutting wires to your ecu and messing with your solenoids????---i mean really-----wtf did u expect?
This thread should be removed before it causes more harm.
Im actually very disapointed to see it.
Some people are complaining of the tranny slipping and not changing gears properly--after cutting wires to your ecu and messing with your solenoids????---i mean really-----wtf did u expect?
This thread should be removed before it causes more harm.
Last edited by 1WILLY1; 10-22-10 at 05:50 PM.
10-22-10, 07:49 PM
#164
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Wow I just read this entire thread from front to back ------im amazed at all the people that were willing to put their car in jeopardy for this miniscule gain in performance--------
Im actually very disapointed to see it.
Some people are complaining of the tranny slipping and not changing gears properly--after cutting wires to your ecu and messing with your solenoids????---i mean really-----wtf did u expect?
This thread should be removed before it causes more harm.
Im actually very disapointed to see it.
Some people are complaining of the tranny slipping and not changing gears properly--after cutting wires to your ecu and messing with your solenoids????---i mean really-----wtf did u expect?
This thread should be removed before it causes more harm.
LOL, modding is a self chosen risk no matter what you do, basically anytime you change it from stock there is a risk, its a risk reward system that not all are willing to take.
10-22-10, 08:15 PM
#165
I know right? I mean what’s next? People putting on coilovers or bags that kill the ride and wear out suspension? Fiberglass body parts that crack, Or turbos that push a crazy amount of pressure on engine internals, talk about a time bomb. They probably will do something stupid like a stall converter or shims in the valve body to make it shift even harder. Fools! Leave your cars stock!
LOL, modding is a self chosen risk no matter what you do, basically anytime you change it from stock there is a risk, its a risk reward system that not all are willing to take.
LOL, modding is a self chosen risk no matter what you do, basically anytime you change it from stock there is a risk, its a risk reward system that not all are willing to take.
To anyone that is going to do this mod ----i would ask you think it over long and hard------
Cutting wires on your ecu ----playing with your trannies solenoids----for a gain that accordiong to some people is barely noticed?
Some people are actually stating that now their tranny is slipping and isnt changing gears properly------i mean come on.
On top of that your car is now throwing codes and your playing russian roulette with your transmission-----im sorry but again-----I dont think anyone that really cares for their car should do this mod----im sorry and it is not my intention to offend anyone-------just my opinion.
Good luck to those that are doing it ---I really hope that there is no real negative side effect---although i would be surprised if there isnt.
And scott on another note-------your car is one of my fav's------I saw it a while back even before I bought my sc400-------I googled images and yours came up----very nice job.
Good luck everyone
Last edited by 1WILLY1; 10-22-10 at 08:18 PM.