LS - 1st and 2nd Gen (1990-2000) Discussion topics related to the 1990 - 2000 Lexus LS400

Throttle cleaning-concerned about touching TPS.

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Old 06-12-18, 05:37 PM
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dame3780
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Default Throttle cleaning-concerned about touching TPS.

Hi all. I have a 90 LS and wanted to clean out the throttle body. I have searched and know how to clean the throttle. My question is about the throttle position sensor. I want to remove the throttle body to fully clean it. If I take the sensor off and on, will this get out of alignment? Or does it only sit in one way? I'm worried I will make things worse if I don't return the sensor to the correct position is all. The 2 screws that hold the sensor on the throttle body appear to allow adjustment. Thanks
Old 06-12-18, 06:22 PM
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spuds
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When you do this,please take pictures if you can.Thanks.
Old 06-12-18, 08:18 PM
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Losiracer2
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Originally Posted by dame3780
Hi all. I have a 90 LS and wanted to clean out the throttle body. I have searched and know how to clean the throttle. My question is about the throttle position sensor. I want to remove the throttle body to fully clean it. If I take the sensor off and on, will this get out of alignment? Or does it only sit in one way? I'm worried I will make things worse if I don't return the sensor to the correct position is all. The 2 screws that hold the sensor on the throttle body appear to allow adjustment. Thanks
Clean it with the sensor on. If you remove the sensor, you'll have to recalibrate it with a multimeter. There are certain voltages it requires at idle and WOT (wide open throttle) otherwise the car won't run properly.
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Old 06-19-18, 05:23 PM
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Originally Posted by spuds
When you do this,please take pictures if you can.Thanks.
I ended up taking it to Lexus since I needed an alignment too. They did both the alignment and throttle cleaning (fuel induction service). The throttle isn't sticking anymore but my idle is still low. The fun continues!
Old 06-19-18, 05:45 PM
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bradland
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Did you mention the low idle to the Lexus Service Advisor ?
I'd start with the simple stuff like slack in the throttle cable. A 90 model has had PLENTY of time to stretch...
Old 06-20-18, 05:30 AM
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Plus one on the throttle cable slack. Easy to check for play in the wire at the throttle body.
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Old 06-20-18, 06:11 PM
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dame3780
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Originally Posted by bradland
Did you mention the low idle to the Lexus Service Advisor ?
I'd start with the simple stuff like slack in the throttle cable. A 90 model has had PLENTY of time to stretch...
Hi, yeah I did mention it. The tech said that the idle was low but it was running/sounding fine. I'm thinking they didn't have much experience with early LS's or they would have attempted to fix it. I will look into the cable more. I have read up on it and even seen diagram on adjusting it but I'm still not grasping how to do it lol. I think I need a video.
Old 06-20-18, 06:30 PM
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bradland
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Super simple. Loosen the 2 nuts with red dots. This will allow the threaded sleeve, cable passing through it, to move in the necessary direction to take up the slack. The sleeve will move by turning both nuts simultaneously in the same direction. Once the sleeve is where you want it, don't go too tight, tighten the 2 nuts.
Old 06-20-18, 07:01 PM
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dame3780
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Thanks for the explanation, it helped! Should I do this with the engine on/off or does it matter?
Old 06-20-18, 07:26 PM
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bradland
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Off
Engines get hot to the touch rather quick when they're running.
Old 06-20-18, 07:45 PM
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I just went out to adjust the cable. It was a little loose. I did as you mentioned. When I started it up, I noticed it turned on quicker when cold. Usually it would take a few seconds but it started quicker. RPM's at warm-up stage were 650-which was higher than before. However, once warmed up, it shot down to 250 (slightly higher than 200 before). Any idea on next steps?
Old 06-20-18, 09:03 PM
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Losiracer2
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i'm not sure but does your 90 have an Idle Air Control Valve? I know in my Honda Accord (93) that it would get dirty over time and need cleaning out with some carb cleaner to bring the idle back up to where it needed to be. You can try servicing that part and see if that helps. At most, would cost $2 for a can of Carb cleaner at Walmart.
Old 06-23-18, 05:25 AM
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dame3780
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It does have one. That's what I was thinking next as well. When I get some time I'll remove and clean it. Thanks for the suggestion-keep the thread updated after completion.
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