99 GS4 with 147k. I notice when I first start the car after sitting overnight, the steering wheel is nice and easy to turn, since the RPM is a little high while it’s warming up. Feels like extra power steering assist. Now if I drive the car around for a few hours and it’s warmed up the rpm at idle drops a little which is normal when it’s warmed up. But when I go to park the steering wheel is much harder to turn and feels like not enough power steering assist when parking. I’ve drain and filled the ps fluid 3 times, changed the air control valve since there was a leak. I notice after each time I change the power steering fluid it’s nice and easy to turn when parking. Then after a few days it’s back to the same. Any ideas what this could be or is this normal for the GS? I know the steering isn’t as easy to turn as an RX or LS but I find it weird that only when the engine is cold it’s nice and easy to turn the wheel with the RPM boost

 

What RPM are you running at when its warmed up? You might try to clean out the throttle to gain a little more rpm at idle. If it's lower than it should be I mean.

 

sorry for the late reply. I have been driving a rental since someone hit my other car. Letting my GS take a rest. But I will double check the idle. When I have the ac on which I always do now in the summer the idle is higher and the issue isn’t noticeable really.

 

that’s how it idles when warmed up after a 1 hour drive in traffic to work. No ac and in drive. I think it idles fine I don’t feel any shaking it’s nice and smooth. I also just tightened the throttle cable and that made it so much more responsive but it didn’t raise idle. I think this is how the GS4 is supposed to idle

 

I’ve been going back and forth between power mode and regular and for sure the steering wheel is easier to turn when using power mode and driving in the street. I guess this is normal since it makes it easier and faster to turn and drive aggressive. In newer electric power steering cars such as a bmw 430 I recently drove, power mode made the steering wheel much harder to turn, almost unbearable and too hard. Weird how it’s the opposite effect on the GS. Street driving it’s easier to turn but on the highway its firmer at high speeds. I have a sport design steering ecu maybe that’s why?