Go Back   Club Lexus Forums > Lexus Model Forums > SC Models > SC 400/300 > Performance & Maintenance
Sign in using an external account
Register Forgot Password?

TPS Throttle Stop Screw Location w picture

Reply
 
 
 
 
Thread Tools Search this Thread Display Modes
Old 06-20-13, 12:58 PM   #1
philllyj
Rookie
Trader Score: (1)
 
Join Date: Apr 2010
Location: PA
Posts: 64
Default TPS Throttle Stop Screw Location w picture

Afternoon, I'm having a time of it attempting to adjust my TPS. I have all the tools to adjust it. Just making sure that this is the Throttle Stop Screw. Please confirm.

Thanks in advance. I'm sorry I may have further questions if I'm not successful.

This ad is not displayed to registered members.
Register your free account today and become a member on Club Lexus!
philllyj is offline   Reply With Quote
Old 06-20-13, 01:07 PM   #2
Bleak
Driver
Trader Score: (1)
 
Join Date: Aug 2009
Location: FL
Posts: 150
Default

what does this do? I wanna know!
__________________
www.facebook.com/thelaststance
Bleak is offline   Reply With Quote
Old 06-20-13, 04:40 PM   #3
O. L. T.
Keeper of the light
Trader Score: (15)
 
O. L. T.'s Avatar
 
Join Date: Feb 2003
Location: 1997
Posts: 33,514
Default

Moved to proper forum
__________________
Mercedes C Class | 19" Staggered Zenetti's | HID's
OESpectrum Suspension | K&N filters | 2" drop

O. L. T. is offline   Reply With Quote
Old 06-20-13, 09:58 PM   #4
durps
Lead Lap
Trader Score: (8)
 
durps's Avatar
 
Join Date: Nov 2011
Location: Jersey
Posts: 593
Default

Yes it is! I have messed with mine myself.
__________________
Join the NELOC section(North East Lexus Owners Club) in the regional forums if you're from the north east!
durps is offline   Reply With Quote
Old 06-20-13, 10:02 PM   #5
durps
Lead Lap
Trader Score: (8)
 
durps's Avatar
 
Join Date: Nov 2011
Location: Jersey
Posts: 593
Default

Wait, what is circled in the pic is actually called the iss, idle stop screw which controls the idle rpm. The actual tps is called throttle position sensor. My car had an issue where it would accel by itself or it would die randomly. Had to mess around with both in order to fix my issue.
__________________
Join the NELOC section(North East Lexus Owners Club) in the regional forums if you're from the north east!
durps is offline   Reply With Quote
Old 06-21-13, 07:22 AM   #6
philllyj
Rookie
Trader Score: (1)
 
Join Date: Apr 2010
Location: PA
Posts: 64
Default

Quote:
Originally Posted by durps View Post
Wait, what is circled in the pic is actually called the iss, idle stop screw which controls the idle rpm. The actual tps is called throttle position sensor. My car had an issue where it would accel by itself or it would die randomly. Had to mess around with both in order to fix my issue.
Thank you Durps, I'm having the same issues, ISS I'm getting somewhere now. So where is the Throttle Stop Screw?
philllyj is offline   Reply With Quote
Old 06-21-13, 12:15 PM   #7
SC400slide
Lexus Champion
Trader Score: (5)
 
SC400slide's Avatar
 
Join Date: Apr 2012
Location: In Recovery mode
Posts: 2,919
Jonathan Hoppman SC400slide Jonathan Hoppman Jonny Hoppman
Send a message via Skype™ to SC400slide
Default

Throttle stop screw is located beneath the iss, generally speaking. Most brutal placement ever. Correct me if I'm wrong...
__________________
1992 Lexus SC400,1995 Lexus SC400, 1996 Ford Explorer, 1971 Oldsmobile Cutlass SOLD, 1992 Ford Explorer SOLD
Lebo Boh tak miloval svet...
Apple Device Intellegentsia
TLN# 49 "Burnt Brownie"
SC400slide is offline   Reply With Quote
Old 06-21-13, 01:58 PM   #8
Ali SC3
Na-T Guru
Trader Score: (10)
 
Ali SC3's Avatar
 
Join Date: Oct 2007
Location: CO
Posts: 6,617
Default

typically you do not want to adjust the idle stop set screw. if you are you finding yourself needing to turn that and you have made no serious changes to your engine, you are most likely covering up the real problem.
most idle issues will be related to adjusting the tps, the black plastic thing on the side with 2 screws.
the idle stop set screw does not need to be moved from where it was set at the factory, unless the idle air valve is completely out of range which doesn't really happen unless they get gunked up or fail, and your idle would be really low. again not a problem with where the screw is set at all.

not sure why you are trying to touch the screw or why you think you have a tps problem but if you keep messing with the throttle body it won't help you will just end up trying to figure out where it was originally set later on and have to play with it a bunch.
__________________

1995 Lexus SC300 5spd Na-T ( TT Ecu Mod + a few others)
Ali SC3 is offline   Reply With Quote
Old 06-25-13, 06:42 AM   #9
philllyj
Rookie
Trader Score: (1)
 
Join Date: Apr 2010
Location: PA
Posts: 64
Default

Quote:
Originally Posted by Ali SC3 View Post
typically you do not want to adjust the idle stop set screw. if you are you finding yourself needing to turn that and you have made no serious changes to your engine, you are most likely covering up the real problem.
most idle issues will be related to adjusting the tps, the black plastic thing on the side with 2 screws.
the idle stop set screw does not need to be moved from where it was set at the factory, unless the idle air valve is completely out of range which doesn't really happen unless they get gunked up or fail, and your idle would be really low. again not a problem with where the screw is set at all.

not sure why you are trying to touch the screw or why you think you have a tps problem but if you keep messing with the throttle body it won't help you will just end up trying to figure out where it was originally set later on and have to play with it a bunch.
Understood. I never touched the ISS. Ali you're the authority on SC's I'm just trying to locate the Throttle Stop Screw in order to set my TPS to spec. I have the digital multimeter, feeler gauges, directions/diagrams, etc. I own a 1992 SC300, 2JZ-GE that's idling wrong since I replaced my TPS. Any help would be great Ali.
philllyj is offline   Reply With Quote
Old 06-25-13, 10:07 AM   #10
Ali SC3
Na-T Guru
Trader Score: (10)
 
Ali SC3's Avatar
 
Join Date: Oct 2007
Location: CO
Posts: 6,617
Default

what are the symptoms you are having now? and what were they before you changed the tps?

Since its idling wrong since you replaced the tps, that confirms it for me that it is just the tps.
First thing I would do is throw the multimeter out the closest window, and adjust the tps by feel.
rotating just the tps alone, believe it or not, will raise or lower your idle depending on the direction you turn it.
you can go by the book, but in my experience thats not always where the engine is happiest.

if your idle is too low, when facing your tps turn it counter clockwise (sc300). it should increase your idle and then you will hit a point about half way through the adjustment range where the car will want to stall out or stumble. at this point you back it off (clockwise) just until it stops doing that. this will give you the max possible rpm's with the idl circuit still operating correctly, and the idle valve then can take care of the rest. edit* I may have gotten the clockwise and counter clockwise backwards but play around with it.

basically, mark your original position and play with the tps, and when you think you have a good spot rev the throttle body by hand to see how it revs and how smoothly it comes back. there is only a small range where it will work fine and idle normally. If I had to guess I would say your tps is probably turned mostly clockwise right now on the adjustment range. if none of that adjustments are working or changing how the motor is running or reacts, then unplug the tps and see if there is a change. if there is no change then you may have a shorted tps on your hands which is possible to have without a check engine light.
__________________

1995 Lexus SC300 5spd Na-T ( TT Ecu Mod + a few others)

Last edited by Ali SC3; 06-30-14 at 11:16 AM..
Ali SC3 is offline   Reply With Quote
Old 06-28-14, 05:04 PM   #11
t2d2
Lexus Test Driver
Trader Score: (3)
 
t2d2's Avatar
 
Join Date: Apr 2014
Location: Oregon
Posts: 899
Default

I'm on an old thread bump today, but at least this one is only a year old.

Ali, as you may recall from a recent thread, I adjusted my throttle stop screw as part of my TPS adjustments (using the multimeter and feeler gauges) to eliminate the partial throttle hesitation/bucking around 40 mph. And shortly after that, the car developed start-stall issues and then the bucking came back.

So, searching for how to properly set the throttle stop screw, I came across this thread and another one with a similar message:

"DO NOT MESS WITH THE STOP SCREW BEHIND THE THROTTLE LEVER. THis is NOT intended to be messed with and once moves is impossible to get back right."

http://www.justanswer.com/lexus/3jmo...ne-starts.html

Ruh-roh. Actually, all may not be lost... I remembered roughly where it was to begin with, and the FSM (FI-73) hints at a pretty simple method of setting it:

"Check that there is no clearance between the throttle stop screw and throttle lever when the throttle valve is fully closed."

Fortunately, the spot where a closed throttle valve coincided with no gap between the screw and lever was right about where I expected it should be. So, I tightened it down there and followed your suggestion to set the TPS by hand; also echoed by Lexls' "unofficial" method:

http://www.lexls.com/tutorials/EFI/tps.html

I had to go all the way counter-clockwise to find a spot the TPS is happy with, surprisingly. And that just barely gives me enough idle (right around 500 rpm). But, with a cracked IACV housing and dead MAF, there could well be other factors at play there. Hopefully, getting those replaced will allow it to find the sweet spot a bit better. I think my prior adjustment of the throttle stop screw (in an attempt to both raise the idle and find a spot where the TPS adjustments could meet the continuity specs), per the method detailed in another thread, had simply disguised the fact that the TPS didn't have enough range due to stuff outside its control.

It's starting right up now and running smooth. If it stays this way for more than 24 hours, I'll be quite pleased.

I'm now a believer in setting the TPS by hand! Doing so with the multimeter was so sensitive, just putting pressure on the TPS while tightening it down was enough to change continuity in and out of spec, let alone actually rotating it.

BTW, are we sure "throttle stop screw" and "idle stop screw" aren't two terms for the same thing, like "idle air control" (IAC) and "idle speed control" (ISC)? The OP's picture sure looks like what the FSM shows as the throttle stop screw.
__________________
'94 SC400 Factory Frankenstein: '00 RX300 steering wheel, '93-96 GS300 speedo/tach needles, '98-02 GS4xx wheels, Prius lug nuts (eco friendly!) ... LS400 calipers denied wheel clearance for take-off.
Performance: Alternative BFI (BeeFI?), A/T Solenoid Bypass, M2/Manzo axleback exhaust (awaiting mid-pipe resonator delete), 2-Tone Driver's Seat ("performance" as measured by the butt test).
t2d2 is offline   Reply With Quote
Old 06-30-14, 11:21 AM   #12
Ali SC3
Na-T Guru
Trader Score: (10)
 
Ali SC3's Avatar
 
Join Date: Oct 2007
Location: CO
Posts: 6,617
Default

Yeah I think I was backwards on the clockwise and the counter clockwise, but I think you got it right when on the right side the motor will want to idle down and that sort of lets you know the IACV is working, and it will want to go to 500-600 rpm's with the a/c off, and that just means you've got everything running well because that is how they are factory you can hardly tell the thing is on till you step on it.

Pretty sure those 2 names are for the same thing the screw is a throttle stop screw, but on older cars that is how you set the idle. on newer Toyota's there is a base position set on the screw at the factory, and then the IACV does the rest, but it still works like before as in you could raise the idle that way, its just not a good idea as it affects other stuff on these newer cars.

if you raise it too much the tps will never sit in the closed position because you can only turn it a certain amount counter clockwise before its going to always read a few degrees open. Also it messes with the EGR system and EVAP system, as those are connected to ports on the top of the throttle body that work by the throttle blade passing it, but if you open the throttle too much via screw, those will not be working right also.
If you make an adjustment small enough to not affect those, usually the idle valve will just adjust back so yeah there is no good way to adjust the idle on these cars, unless you have all that stuff removed then feel free to riase it up to whatever, like I used to with my q45 throttle body and FFIM I would have it idling at 1200 rpm's via the screw just so I could get better cold starts.

Generally you wont be doing this stuff though if you want it to be like stock, unless someone has done it before you incorrectly. look for the factory paint mark on the screw and see if it lines up.
__________________

1995 Lexus SC300 5spd Na-T ( TT Ecu Mod + a few others)

Last edited by Ali SC3; 06-30-14 at 11:26 AM..
Ali SC3 is offline   Reply With Quote
Old 06-30-14, 04:05 PM   #13
t2d2
Lexus Test Driver
Trader Score: (3)
 
t2d2's Avatar
 
Join Date: Apr 2014
Location: Oregon
Posts: 899
Default

I don't think my stop screw had a factory paint mark, unless that's what the orange stuff was that looked like thread lock? If that was a paint mark, then someone had adjusted the stop screw previously by moving the nut down over the mark. I scraped it all off when doing the first adjustment, so I don't have that mark to go back to...

Any idea what would cause a sucking sensation when letting off the throttle at 60 mph? It feels like the throttle plate is being sucked closed when straddling that fine line between light throttle and coasting. I'm guessing I still don't have the stop screw set quite right, but the IAC/MAF issues could be to blame. Also, I played with the Dashpot a bit (didn't end up changing anything) prior to that, and its purpose sort of seems like it could come into play there, by letting the throttle plate to close too quickly.
__________________
'94 SC400 Factory Frankenstein: '00 RX300 steering wheel, '93-96 GS300 speedo/tach needles, '98-02 GS4xx wheels, Prius lug nuts (eco friendly!) ... LS400 calipers denied wheel clearance for take-off.
Performance: Alternative BFI (BeeFI?), A/T Solenoid Bypass, M2/Manzo axleback exhaust (awaiting mid-pipe resonator delete), 2-Tone Driver's Seat ("performance" as measured by the butt test).
t2d2 is offline   Reply With Quote
Old 07-02-14, 09:52 AM   #14
Ali SC3
Na-T Guru
Trader Score: (10)
 
Ali SC3's Avatar
 
Join Date: Oct 2007
Location: CO
Posts: 6,617
Default

no idea what you are talking about with the sucking sensation. if you have your foot even slightly on the throttle none of the screws are going to help you. you really adjust those at idle when motor is warmed out and it should be 95% backed out the screw. you kind of turn it all the way out and then turn it in till you feel some resistance, thats when it actually moves the plate. right there where you hit the resistance is about the right place to lock it down, maybe a hair past.

the dashpot keeps the throttle plate open for a sec on rapid deceleration to allow extra air in to keep from backfiring and getting a clean burn for emissions.
__________________

1995 Lexus SC300 5spd Na-T ( TT Ecu Mod + a few others)
Ali SC3 is offline   Reply With Quote
Old 07-02-14, 10:57 AM   #15
t2d2
Lexus Test Driver
Trader Score: (3)
 
t2d2's Avatar
 
Join Date: Apr 2014
Location: Oregon
Posts: 899
Default

That's exactly how I set the stop screw. It's probably due to something else in the chain of parts awaiting replacement... I can't think how else to describe the throttle plate sucked-closed sensation. It would be obvious what I mean if you felt it.
__________________
'94 SC400 Factory Frankenstein: '00 RX300 steering wheel, '93-96 GS300 speedo/tach needles, '98-02 GS4xx wheels, Prius lug nuts (eco friendly!) ... LS400 calipers denied wheel clearance for take-off.
Performance: Alternative BFI (BeeFI?), A/T Solenoid Bypass, M2/Manzo axleback exhaust (awaiting mid-pipe resonator delete), 2-Tone Driver's Seat ("performance" as measured by the butt test).
t2d2 is offline   Reply With Quote
Old 07-02-14, 10:57 AM
 
 
 
 
Reply

Tags
2jzgte, adjust, adjustment, body, car, club, control, lexus, location, ls400, mazda, sc400, screw, set, stop, throttle

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
NH 1995 SC300 RED w/Black Int. 166K Clean $3500 Nazar Lexus Vehicles Classifieds 0 09-09-14 01:43 PM
SC300, Stereo and HDR Images, XXR522 Ian300D SC 400/300 4 08-17-13 03:44 PM
PA 1992 SC300 OEM Passenger Left Door Parts philllyj SC400 / 300 Classifieds 1 04-20-13 03:52 PM
SEM - Seats, Doors, Console, Wheel, Wood Grain, Parking Brake - ton of pics philllyj SC 400/300 42 03-12-13 08:53 AM
GS300 2004 spark plug DIY changes with lots of pictures akobari GS - Second Generation 9 03-03-13 06:42 PM

All times are GMT -7. The time now is 12:53 AM.

Join ClubLexus
Advertising


Copyright © 2000-2008 Internet Brands, Inc. All Rights Reserved
Privacy Policy | Disclaimer | Terms of Use | JOBS


Get all contact info