Lexus IS Forum banner

1 - 20 of 45 Posts

·
Premium Member
Joined
·
5,207 Posts
Discussion Starter #1
Tired of the dead zone at the top of the throttle pedal where nothing happens? This occurs because Lexus placed a small spring on the throttle cable where it mounts to the pedal. This helps dampen any vibrations in the throttle cable as well as gives a smoother throttle input by dampening initial inputs.

What You'll Need:
flashlight (its pretty dark in the footwell)
phillips head screwdriver (optional)
small piece of rubber hose (fish tank hose works well, or others, I used some extra 5/16 inch SAE hose I had laying around
zip tie to secure the hose
-or-
hose clamp instead of hose and zip tie (for you sanity I would suggest the rubber hose, I originally used a hose clamp which was much more difficult)

To modify the spring on the pedal, you need access to the topmost portion of the throttle pedal, looking up from under the dash, this is where we are working, the throttle pedal is going down out the right side of this photo. Because my original photo didn't turn out very well, this is with the spacer already installed, though you can see the spring we are neutralizing through the slot in the rubber hose.


If you can reach up there without removing the panel below the steering wheel, there is definitely much less work involved and you can skip the next couple photos which address getting this panel off for extra room to maneuver.

If you need to get the panel off, start by pulling up the door trim and opening the fuse panel door, the fuse panel door blocks the panel from dropping down and the door trim prevents the fuse door from opening. The trim at the bottom of the door is simply clipped in and needs to be firmly lifted to pop the tabs out of the clips and remove.



The fuse panel door is also on steel clips and requires a firm pull to pop it out, grabbing the outer edge and pulling towards the back of the car and then into the car will remove it the easiest, this only flips out of the way into the footwell as the front of it remains attached.


Next, unscrew the phillips head screws attaching the panel, they are at the bottom left and right of the panel as well as just below and right of the steering column. A couple clips will hold the panel up after the screws have been removed, pull gently and the panel should come off without much force, other connections behind the panel will prohibit the panel from moving too far, these will have to be removed to completely remove the panel.




Next you have to disconnect the hood release, OBDII port and a couple other connections keeping the panel from dropping away.

Behind the blank panel to the left of the steering column, you have to press on the outboard side of the connector to release it from the blank filler panel. *This is an '02 manual car w/o memory seats, your car may be different*


On the right side, near the vent and blank filler panel, remove the white hose simply by pulling and the blue connector by pushing on the tab and pulling.


Remove the cap from the OBDII port and pinch the sides of it on the outside of the panel, simultaneously pushing it through to the back of the panel to free it.


Remove the hood release cable from the slot behind the latch


Remove the cable from the latch by pulling the cable out of the slot and pulling the barb to the outboard side of the latch. *I removed the latch from the panel to get a better photo, its removal is not necessary and it will not fit through the back of the panel(it would be much easier if it did, the hood latch is the most difficult part to reassemble)


The panel should now be free to be removed from the car.


I used a small piece of 5/16" automotive hose which I cut with a fine-tooth hacksaw, a razor blade will also work but it is more difficult. I then sliced the piece open with a razor blade so it could be simply placed over the spring.



Simply slip the rubber hose over the spring between the whitish plastic pieces and secure with a zip tie, cut off the excess tail of the zip tie.



Alternatively, you can use a hose clamp by opening it up all the way, putting it over the spring and then tightening it down. This is the way I originally did the modification over a year ago, it was much harder to tighten the hose clamp on than it is zip tying a piece of hose over the spring. I also feel that the rubber hose gives a much better feel as it doesn't shift around as the metal hose clamp did.


Re-attach the connections behind the panel, replace the panel, fuse box door, and door trim.

After performing this modification, make sure your throttle cable has not been affected by checking for slack at the adjustment point at the throttle body. Alternatively, start the car and let it warm up, make sure the car idles properly, if the modification made the throttle cable too tight, a small throttle input will keep the car from dropping down to its regular idle, once the car is warm, it should idle below 1000rpm. If it does not, follow the throttle cable adjustment tutorial to loosen the cable.
 

·
Registered
Joined
·
69 Posts
Excellent write-up.........I'll be doing this mod soon.
Can you advise to what length you cut the rubber hose that was installed?
 

·
Premium Member
Joined
·
5,207 Posts
Discussion Starter #3
somewhere around 1/4" to 3/8" probably closer to 3/8"
 

·
Registered
Joined
·
1,824 Posts
I tried this: put in a 3/8inch spacer. The car was idling waaayyy too high, at about 2200rpm. I let it warm up, but it still didn't drop.
So i said f*ck it....I took it out
 

·
Premium Member
Joined
·
5,207 Posts
Discussion Starter #6
I tried this: put in a 3/8inch spacer. The car was idling waaayyy too high, at about 2200rpm. I let it warm up, but it still didn't drop.
So i said f*ck it....I took it out
As long as you are not stretching the area the spring is in, idle should not be affected. You just want to modify it so that the spring cannot compress as you press on the accelerator.
 

·
Registered
Joined
·
1,129 Posts
Awesome write-up. This literally took me 5 min... just used 4 zip ties tied in a circle instead of the hose and did not even have to remove the under dash... it makes a world of difference...
 

·
Premium Member
Joined
·
5,207 Posts
Discussion Starter #9
...or just take the slack out of the throttle body wire up by the motor.
Taking the slack out of the line by the motor will help if there is slack there; however, it will not change the fact that this spring is on the line dampening your inputs as well.
 

·
Registered
Joined
·
389 Posts
Tired of the dead zone at the top of the throttle pedal where nothing happens? This occurs because Lexus placed a small spring on the throttle cable where it mounts to the pedal. This helps dampen any vibrations in the throttle cable as well as gives a smoother throttle input by dampening initial inputs.

What You'll Need:
flashlight (its pretty dark in the footwell)
phillips head screwdriver (optional)
small piece of rubber hose (fish tank hose works well, or others, I used some extra 5/16 inch SAE hose I had laying around
zip tie to secure the hose
-or-
hose clamp instead of hose and zip tie (for you sanity I would suggest the rubber hose, I originally used a hose clamp which was much more difficult)

To modify the spring on the pedal, you need access to the topmost portion of the throttle pedal, looking up from under the dash, this is where we are working, the throttle pedal is going down out the right side of this photo. Because my original photo didn't turn out very well, this is with the spacer already installed, though you can see the spring we are neutralizing through the slot in the rubber hose.


If you can reach up there without removing the panel below the steering wheel, there is definitely much less work involved and you can skip the next couple photos which address getting this panel off for extra room to maneuver.

If you need to get the panel off, start by pulling up the door trim and opening the fuse panel door, the fuse panel door blocks the panel from dropping down and the door trim prevents the fuse door from opening. The trim at the bottom of the door is simply clipped in and needs to be firmly lifted to pop the tabs out of the clips and remove.



The fuse panel door is also on steel clips and requires a firm pull to pop it out, grabbing the outer edge and pulling towards the back of the car and then into the car will remove it the easiest, this only flips out of the way into the footwell as the front of it remains attached.


Next, unscrew the phillips head screws attaching the panel, they are at the bottom left and right of the panel as well as just below and right of the steering column. A couple clips will hold the panel up after the screws have been removed, pull gently and the panel should come off without much force, other connections behind the panel will prohibit the panel from moving too far, these will have to be removed to completely remove the panel.




Next you have to disconnect the hood release, OBDII port and a couple other connections keeping the panel from dropping away.

Behind the blank panel to the left of the steering column, you have to press on the outboard side of the connector to release it from the blank filler panel. *This is an '02 manual car w/o memory seats, your car may be different*


On the right side, near the vent and blank filler panel, remove the white hose simply by pulling and the blue connector by pushing on the tab and pulling.


Remove the cap from the OBDII port and pinch the sides of it on the outside of the panel, simultaneously pushing it through to the back of the panel to free it.


Remove the hood release cable from the slot behind the latch


Remove the cable from the latch by pulling the cable out of the slot and pulling the barb to the outboard side of the latch. *I removed the latch from the panel to get a better photo, its removal is not necessary and it will not fit through the back of the panel(it would be much easier if it did, the hood latch is the most difficult part to reassemble)


The panel should now be free to be removed from the car.


I used a small piece of 5/16" automotive hose which I cut with a fine-tooth hacksaw, a razor blade will also work but it is more difficult. I then sliced the piece open with a razor blade so it could be simply placed over the spring.



Simply slip the rubber hose over the spring between the whitish plastic pieces and secure with a zip tie, cut off the excess tail of the zip tie.



Alternatively, you can use a hose clamp by opening it up all the way, putting it over the spring and then tightening it down. This is the way I originally did the modification over a year ago, it was much harder to tighten the hose clamp on than it is zip tying a piece of hose over the spring. I also feel that the rubber hose gives a much better feel as it doesn't shift around as the metal hose clamp did.


Re-attach the connections behind the panel, replace the panel, fuse box door, and door trim.

After performing this modification, make sure your throttle cable has not been affected by checking for slack at the adjustment point at the throttle body. Alternatively, start the car and let it warm up, make sure the car idles properly, if the modification made the throttle cable too tight, a small throttle input will keep the car from dropping down to its regular idle, once the car is warm, it should idle below 1000rpm. If it does not, follow the throttle cable adjustment tutorial to loosen the cable.
I did this using a thick cable tie and it works good. also adjusted at at the motor, not too much though. Its a lot better still not as responsive as i like, i like to be able to feather it quick, like really quick. But definitely better.
 

·
Registered
Joined
·
488 Posts
Is it possible to cut that spring and then just tighten the slack, thus not worrying about having to put any spacer at all?
 

·
Registered
Joined
·
4 Posts
Thanks, it works and it's easy to do. Just took car out briefly and I could actually manage to properly rev match on downshifts, which I've been struggling with since I bought it a year ago. A must for manual transmission owners.

But still seems a little disconnected compared to other cars I'm used to.
 

·
Registered
Joined
·
4 Posts
I've had my car for a year and a half now, and always *hated* the initial throttle tip in when leaving from a stop. Mine is a 2002 Sportcross (which means automatic transmission). When leaving from a stop (no matter how controlled I was with the throttle) the car would accelerate normally for a split second, then slightly decelerate, then accelerate again. It drove me bonkers!!!

Anyway, I did this mod tonight (using fuel hose and zip tie) and the problem completely dissapeared. I feel like I'm driving a regular car again :eek:) Sure, the throttle isn't as snappy as a direct cable, but at least the initial surge is gone.

Great write-up!
-Dan
 

·
Registered
Joined
·
229 Posts
THIS MOD IS AWESOME!

Just did it a few weeks ago and the difference is day and night.


I can finally rev match on a downshift! I didn't bother taking apart the footwell. I just squeezed in there. :p

I cut a piece of fish hose I had lying around for my turtle tank and 2 small zip ties. Worked like a charm.

+rep ;)
 

·
Registered
Joined
·
75 Posts
This is exactly what I've been looking for. I just assumed the input was part of DBW and couldn't be helped. I'll be doing this first thing tomorrow morning.

+rep
 

·
Registered
Joined
·
547 Posts
Wow, this is taking us back to 2005. See the note below and be sure to add this shim for throttle stop.

___________________________

A caution to those that has done this mod.

By putting on the spacer, you actually reduce the travel of the gas pedal from 100% to approx. 85%. With this mod, at Wide open throttle, the throttle pedal will not bottom out to its previous position, even though the throttle body is 100% open.

The implication is that throttle stop is now limited by only the throttle body, and no longer the pedal. If a driver uses excessive force to floor the pedal, he may break the stop at the throttle body or the cable itself. I do not know if this is realistic but it is a possibility that I do not want to find out so I put in a shim on the round rubber stop below the gas pedal to act as a secondary stop.

I spent some time investigating this and learned that for stock (unmodified) setup, the stop on the throttle body would act as a primary stop. If a driver pressed harder, the linkage may deform a little more (1 mm) and thus allow the pedal to move this additional 1mm. At this point, the gas pedal hits the secondary rubber stop. I belive this secondary stop is there to protect against overstressing the throttle linkage, so it is crucial that this secondary stop is maintained by taping or epoxying a shim in place. Be careful that the shim is not too thick or else, this shim will act as your primary stop instead of the secondary, thus preventing the throttle body from being fully open.

The picture below is from CEB.

 
  • Like
Reactions: Matt K

·
Registered
Joined
·
7 Posts
lk250f;6107210 begin_of_the_skype_highlighting**************6107210******end_of_the_skype_highlighting said:
I did this using a thick cable tie and it works good. also adjusted at at the motor, not too much though. Its a lot better still not as responsive as i like, i like to be able to feather it quick, like really quick. But definitely better.
your not really going to see that much of a change, the only way you will see a lot of throttle response is by doing an 80mm tb upgrade. ebay also sales a 90mm tb idk how well it is but 90mm that's huge!

Here ya go, bro, this will give you info on the 80mm TB upgrade
http://my.is/forums/f114/80-mm-tb-n-420534/
 
1 - 20 of 45 Posts
Top