CFooo

About 6 months ago, my 1999 RX300 with about 54k miles started to have rough (low idle and sometimes dies) idle problem. I took apart and cleaned the Idle Air Control Valve and the rough idle problem went away.

Lately, intermittently, when I start the car, it will sometimes idle high (about 1700 rpm and stay up there for a while when I drive vs. the normal of about 1100 then drops to 700). Since this only occurs about once every 10 to 20 starts, I am puzzle at what can cause this. Any help will be appreciated. Thanks.

C_Fooo

code58

When you took it apart to clean, how did you clean it and with what? Was the little round cylinder that fits into the electromagnet REALLY free when you would rotate it? And did it always come back to about 1/16 to 3/32 of opening on the slot when at rest? Always a possibility that there is a problem with the electromagnet or the plug that goes on the EM or the feed to the plug. You do realize that the Bakelite with the EM in it has a small amount of adjustment by loosening the screws and you should be able to remove those 2 screws and either take the EM off and rotate the valve by hand or simply rotate the Bakelite part (in place with the screws removed) and get pretty much FULL range from open to closed to see what it does then. You should be able to do this with it running. Check the plug by "reseting" (remove and reinsert) it about 3 or 4 times to make sure the contact is good in that. Shoot a very small shot of tuner cleaner and lube (Radio Shack) in the plug before you reset it.

CFooo

Hi Code58, thank you for trying to help. I am not very familiar with how things work so please be patient with my questions.

To answer your question, I used CRC brand Throttle Body & Air-Intake Cleaner to clean out the muck inside.

Since this intermittent high idle didn’t start until 6 months later, could what I did when cleaning the IACV cause this problem? Sorry for my question, but wouldn’t it happen sooner if it was related to the IACV cleaning?

Anyhow, trying to figure out the problem, I am not sure what you meant by “Bakelite with the EM in it has a small amount of adjustment by loosening the screws and you should be able to remove those 2 screws and either take the EM off and rotate the valve by hand or simply rotate the Bakelite part (in place with the screws removed) and get pretty much FULL range from open to closed to see what it does then. You should be able to do this with it running. Check the plug by "reseting" (remove and reinsert) it about 3 or 4 times to make sure the contact is good in that. Shoot a very small shot of tuner cleaner and lube (Radio Shack) in the plug before you reset it.”?

Since this is only an infrequent occurrence, it is hard for me to troubleshoot unless it is happening and I can see something wrong visually without taking anything apart. Unless it is like the muck problem and all I need to do is to clean something. Should I wait until it happens more often or would the high idle which will go away in about a couple minutes of driving, cause major damage (or just waste some gas)?

C_Fooo

code58

Do you have a compressor? I always believe in blowing everything out really good when I clean anything. You can take the "electromagnet" off by removing the 2 Phillips screws on the "bakalite" (That's the brown or black part that the plug plugs into). You don't have to drain any coolant that way and you have access to the little round "barrel" that fits inside the (bakalite) electromagnet. You should be able to take the "barrel in you thumb and forefinger and rotate it FREELY. It will return to the MOSTLY closed position. But you should also be able to remove the screws with it running and rotate the "bakalite" part without unpluging or pulling it away from it's seat, to it's extreme open and close position and thereby control the idle to it's extreme high and low positions also. As I said before, WITH THE "bakalite"/electromagnetic fitting OFF, you should be able to control the idle to those same extreme positions by rotating the little barrel with your 2 fingers as it doesn't look like it should leak vacuum. Very easy to show, not near as easy to put into words. Try that and see how it goes. Let me know and I'll give any further help that I can.

CFooo

Hi Code58,

See attached pictures:
Is this the round cylinder you are referring to?


Is the plastic part that attached to this cylinder the EM?


C_Fooo