I posted a while back about cold idle issues with my 1999 RX300: Testing Idle Air Control Valve

I installed a new Denso IACV (purchased from the dealership). While replacing it, I thoroughly cleaned the throttle body, including the air passage on the right side that feeds the IACV. All new gaskets. I pulled the EFI fuse afterward as well. (Is there a separate fuse for the ECU?)

When cold, the car will usually start ok, and hold a 1200 - 1500 idle for a bit, and slowly drop over a couple of minutes. The problem is that if I put the car into gear too soon, the car stumbles and dies.

I'm wondering if there is something else I'm overlooking? Are there other cold-condition components that might be at fault?

Thanks for any suggestions.

 

When I first cleaned my IACV I thought I did a good job but a couple of days later the car was stalling at idle.

When I rechecked it I found when rotating the valve it felt like it was binding.
I redid the cleaning, this time plugging that little tube at the bottom, spraying lots of cleaner in the top, and rotating the valve back and forth a lot.
I unplugged the tube and the cleaner and black particles drained out.
I repeated this a few times until the valve rotated back and forth very smoothly and no further particles came out.

Idle has been fine ever since.

 

When you say - cleaned it - did you actually take it apart? It's coolant temperature reliant. When I cleaned Civic IACV and took it apart, it was like old drain pipe inside - all filled with calcium build up and what not. Also, how fast does your coolant temperature build up?

 

Cleaned as described here:
https://www.clublexus.com/forums/rx-...ml#post9204015

But I didn't read your posts carefully enough. I thought you replaced the electronic part, it sounds like you replaced the entire valve.
Sorry for the noise

 

OK, so you sprayed cleaner into the valve area. I was referring to taking apart the section that coolant goes through.
Also, OP, it just came back at me. Check your temperature sensor. Coolant temperature. Those are known and well omitted, culprits of poor starting and poor idle, as they confuse ECU with false readings.