the idle in our lexus seems rough but only when you are coming to a complete stop or changing from park to reverse to neutral or to drive. the rpm seems to raise a bit when i change and you can feel it. wanted to know if there is anything i can do to keep the idle smooth through shifting. it has 74,000 miles and we just bought it. please help i can't afford to take it in.

 

What about when your GX is in Park/neutral? Hi rpms?

 

Welcome to the Club.

Your GX may suffer from an issue that we have found on the RX300, and would involve cleaning out the IACV valve of the throttle body. This not too difficult of a task, but unfortunately I don't have pictures of your specific vehicle. The valve itself can get dirty and stick open and usually needs just some throttle body or carb cleaner to be shot into the IACV for a few seconds.

 

i'm not sure if it does it when i'm in park, it does sometimes, it's pretty random, it does it at different times and sometimes not at all. but i'll try spraying the carb cleaner and get back to you guys on that. thanks for the tips i'll keep you posted.

 

I've been wondering about this IACV issue for awhile. It seems like the IACV on the 1st gen RX300 which I have is more susceptible to getting dirty(I cleaned it about 3 to 4 times) than the GX470 IACV. I am basing this thinking because my gx470 has ~234k miles on it and never have this issue. So curious mind wants to know , is the GX470 IACV part design makes it less vulnerable to getting dirty? I've seen the part but just don't know how it works/interact with the other components.

 

The 4.7 liter V8 doesn't have an Idle Air Control Valve - it uses a computer-driven throttle motor. There might be an aftermarket available that is sold separately, but Lexus only sells it as part of the throttle body for $650.

https://www.lexussouthatlantaparts.com/showAssembly.aspx?ukey_assembly=780914&ukey_make=1082&ukey_model=15663&modelYear=2004&ukey_category=21750&ukey_driveLine=8091&ukey_trimLevel=19100

I would look at cheaper causes of rough idle first. Are the spark plugs the correct Denso/NGK ones? Get the codes read for a misfire to see if a ignitor is bad. Check for a clogged PCV valve. Run some Seafoam fuel system cleaner through it (follow the directions on the bottle). Is the air filter clean, and there's no air leaks from the filter to the throttle body??

Chip H.

 

I have lexus lx470, and I have been having problem with high idle. We have clean all air intake with throttle spray. also on and off 2 time then start it on a drive with handbrake on for 8 minutes and still the same.
I'm located in Palau so it's hard to get services

 

Nice place to live. I follow some people on YouTube who are in Tonga.

Check the things I mentioned earlier - correct and fresh spark plugs, vacuum leaks, computer codes. See if the A/C system is working correctly (RPMs will be higher when the compressor clutch is engaged)

Chip H.