Michael88

I will be adjusting this, and was hoping someone might help me by listing the procedure. I have read the tutorial, but this is a 98 and is different. This is the first year with the electronic throttle motor, different from previous years Throttle Position sensor. For many years I experienced occasional sluggish accelerator response from a dead stop and cold engine. This progressed to intermittent no start situations with a warmed engine with humming coming from the throttle motor. When this happens I can disconnect the battery, unplug the accelerator position sensor, wait, plug it back in, reconnect the battery; then she will start just fine. I have new alternator and battery. I have tighten the throttle cable, just to tack 20 years of slack out, but need the procedure to adjust the accelerator position sensor, please. It is my understanding that Lexus designed a "fail safe" electronic throttle, and thus meaning the car can't over accelerate when the sensor needs calibrated or replaced. The result is a zero throttle situation being safer than an over acceleration situation. I believe this is what I am seeing during intermittent no starts that can be cleared by resetting the computer through battery disconnect.

Michael88

So, I inspected every vacuum hose and found a large crack in the back of the hose going from the PCV valve to the front of the intake. It was hidden from top and front inspection. I had to remove it in order to see the crack. A big air leak I would say. So, anyone having idle issues should do a total vacuum hose removal and inspection plus spray starting fluid at all connections and around the intake listening for engine revving up. If it does, then you have an air leak there. DO NOT get teh electronics wet, though. These cars can't take the wetness. So far, I have no problems starting the car, but you never know. Stay tuned.

Yamae

Was the crack like this?
https://www.clublexus.com/forums/ls-...8-celsior.html

Michael88

It was exactly like this. Almost, to perfection. Absolutely, must be noted as a common fault on these LS400s after twenty years.

Yamae

It was back in 2011 when my Celsior was 13 years old. After I have posted, I suggested Celsior owners around me to check it. They found exact the same problems commonly. 98-00 LS400/Celsior owners need to check the hose removing it because the crack is at the lower side.