My wife's 1999 Rx300 had been running fine. We had a block replacement due to the dreaded oil gel problem about 2 years ago and have about 115,000 on the car. We have not had a full tune-up in a while.
Just the other morning it got cool down here and the car wouldn't start normally. It will fire just fine, but won't hold ANY idle. If I keep my foot on the gas, it will run normal with no hiccups, but as soon as I release the gas pedal, it dies. I've warmed it up to full running temp, but it still dies immediatelywhen I take pressure off the gas pedal. I've removed the air filter (looks OK) and same story. I've pulled the battery cable trying to reset sensors, no deal.

Any help is appreciated.

 

get it to the dealership for a diagnosis

 

Did you get any kind of check engine light after it would do this?

 

Common problem. It's the Idle Air Control Valve (IACV). If you go to the dealer he will charge big bucks to replace. If your handy you can clean it yourself or have the procedure done. Dealer does not like to clean just replace. Do a search here for IACV for the procedure and a lot more info and suggestions.

 

NO check engine light.

Could it actually be the IACV? so suddenly and so completely?

 

I wouldn't doubt as mikey00 says that something is wrong with the IACV, but it is very odd to me that no check engine light would occur. Other possible suspects include a dirty MAF sensor, a hose on the back of the airbox. There might also be some fuel line blockage including in the injectors.

Still, there should be a check engine light. The only time the light goes on and then goes off would be when something corrects itself. Often a P0171 lean error (the most common RX300 error) can correct itself (if it was just a reading as opposed to a problem with a part) after about 3 starts. I have seen this when I drop in altitude on trips to Texas before I had the OBDII sensor handy along with the EFI trick.

I would still take it to an Autozone and see if a code does exist in the system, regardless of whether a light appears.

 

Well, now I did it. Didn't have anyone to keep the car running, so I just sprayed about 1 1/2 seconds of carb cleaner in to the IACV port and now the sucker won't start at all. I've tried warming the area up with a hair dryer to evaporate any excess cleaner, but still no go!

 

Let it sit a while and try restarting. First try starting normal way, without use of gas pedal. If it won't start try using the gas pedal. It should start eventually.
If you used gas pedal to keep it running with your initial problem things would have been ok once it warmed up. But problem would have returned with next cold start. If you do any more cleaning follow the procedure. Have the engine warm and keep it running.
I do agree with Lexmex about getting the code read with a CEL. Problem is this situation often occurs without a CEL initially.

 

I want to thank you guys for the info. A little patience and more cleaning and ....now she run!

Does anyone have more detail on taking apart the IACV and cleaning it well?
Thanks again.

 

Glad to hear it started. If you just do a search on IACV in this forum there is a lot of info with pics. Here is a link to a 'how to" at another site:
http://us.lexusownersclub.com/forums...howtopic=30723

 

Thanks for the link and the info...this was my first venture on this forum. I Likey, Mikey.

 

I had a same problem with my old Isuzu Rodeo ... went to AdvancedAuto and they suggested it could either be IACV or Thottle Position Sensor. I tried TP and it went away.