Correct Idle?

LexusWoman · February 17, 2004

I noticed that when I come to a stop light, my idle is dropping pretty low....looks like 400rpm (less than halfway mark). What shoudl it be at and any idea on correcting this? I habd a fulkl blown 30K Lexus tune Up 6 months ago. I have an aftermarket air Filter Intake. Nothing Else.

When I change to Park or Neutral or revers....all is better.

thanks

VMF · February 17, 2004

there are a lot of different reasons why this might happen you will have to provide more info about this. you also posted it in the wrong forum, i'm gonna move it to gs forum

Neo · February 17, 2004

Ah, the infamous low/rough idling issue. The GS has a history of this problem. If the car is under warranty, I would take it to the dealership. If not, there have been varying success with cleaning the throttle body, the MAF, and/or replacing the 02 sensors.

Now the quickie solutions have been to drive with either AC and/or headlights on. Don't laugh, Try it. ;)

TWINTURBO619 · February 18, 2004

I noticed that when I come to a stop light, my idle is dropping pretty low....looks like 400rpm (less than halfway mark). What shoudl it be at and any idea on correcting this? I habd a fulkl blown 30K Lexus tune Up 6 months ago. I have an aftermarket air Filter Intake. Nothing Else.
When I change to Park or Neutral or revers....all is better.

thanks

you might want to adjust the air to fuel ratio screw that's on your throttle body to raise the idle a bit. at a norm, my gs idles at about 800 rpm. good luck

GuyTelefunken · February 19, 2004

Are you kidding me? As far as I know, there is no way to change the idle with any screw. The idle speed is controlled by the ETCS ECM (Electronic Throttle Control System Electronic Control Module) and that is that. It can be changed by loading, such as a problem in the drivetrain or when a sensor(s) has gone bad, but that's about it. Correct me if I'm wrong, but I know of no screw on a 99 GS400.

According to the manual, the target range for the 1UZ–FE V8 is 750 ± 50 rpm, in neutral with the air conditioner off. It is completely normal for the idle to drop by some degree when shifted into a non-neutral gear. You'd be hard pressed to find any automatic that didn't. As far as Lexus is concerned, I see no specification as to how much is acceptable.

If it does not stall, or attempt to stall, it's most likely that all is as it should be.

Jcfierros18 · July 19, 2014

Are you kidding me? As far as I know, there is no way to change the idle with any screw. The idle speed is controlled by the ETCS ECM (Electronic Throttle Control System Electronic Control Module) and that is that. It can be changed by loading, such as a problem in the drivetrain or when a sensor(s) has gone bad, but that's about it. Correct me if I'm wrong, but I know of no screw on a 99 GS400.

According to the manual, the target range for the 1UZFE V8 is 750 ± 50 rpm, in neutral with the air conditioner off. It is completely normal for the idle to drop by some degree when shifted into a non-neutral gear. You'd be hard pressed to find any automatic that didn't. As far as Lexus is concerned, I see no specification as to how much is acceptable.

If it does not stall, or attempt to stall, it's most likely that all is as it should be.

The "screw" he's talking about is the tps..of course you'd tighten it back up once adjusted..at least that's the case on my gs300 when I replaced it and the apps