Idle Air Control

[w77]

Can someone tell me where the Idle Air Control Motor is located and how it looks like on the IS200 please. Thanks.

Richard

[flyeris]

Can someone tell me where the Idle Air Control Motor is located and how it looks like on the IS200 please. Thanks.

Richard

In addition to the previous question, is it somehow possible to control the idle rpm on the Lexus or is it completely controlled by ECU?

[w77]

Anybody?

[gsportcars]

The idle on the IS200 is controlled via the drive by wire throttle body. There is no seperate IAC valve. Everything is controlled by the DBW.

Why do you guys want to adjust the idle speed? Is it idling too slow or fast? If so then I would expect there to be a problem somewhere.

[w77]

The idle on the IS200 is controlled via the drive by wire throttle body. There is no seperate IAC valve. Everything is controlled by the DBW.

Why do you guys want to adjust the idle speed? Is it idling too slow or fast? If so then I would expect there to be a problem somewhere.

Thanks. It's because the malfunction light comes on everytime and comes off after a day or two. I had it diagnosed and the code was P0505 which was Idle Control Malfunction. It idles just above 5000 rpm and I think it is lower than before. Performance is not affected anyway. Is it bad to drive it with the malfunction light on?

I've read on the internet that this problem is normally caused by a faulty Idle Air Control Valve and cleaning it normally solves it. Since you said that it doesn't have a seperate IAC valve, what normally causes it? Will cleaning the throttle body help? What's the best way to clean it? Sorry for too many questions.

[gsportcars]

I assume you mean it is adling at just over 500rpm? (not 5000rpm lol)

It could well be sticking when trying to make tiny adjustments to hold the idle steady. The throttle plate will always be making tiny movements for a steady idle. Cleaning it would be the first thing to try. Remove the throttle body and use some carb cleaner and a toothbrush or something to get into the crevices etc. make sure the throttle plate is moving freely and you could spray a small touch of WD40 in there before re-fitting it.

That should definately help it but if it doesn't then I would suspect the motor for the drive by wire is maybe knackered. You could buy a complete throttle body with a motor from a breakers yard and try that.

[Rob]

the only drive by wire on the IS200 is the big steel control cable that goes from the pedal to the throttle body - a servo fine tunes the butterfly

[w77]

Thanks.

[mrdalethomas]

Thanks.

take the air box off it should be on the opposite side of the body where the cable goes. it has 2 screws to turn the sensor. got same problem. but not got the time so i adjusted the 2 screws above where the cable sits. easy but dont do it to far olol

[WGC_Bloke]

IS 200 - Realise this is an old thread, but I have a high idle (1500+), but when driving (even foot off pedal) rev seem OK. I'm guessing the IAC motor is crudded up, so want to get a tooth brush in there with some carb cleaner (I'm guessing this is correct remedy). Three similar looking "things", I'm guessing 2 are throttle position sensors and the third the IAC motor. None of these are easily accessible (injector bar is in the way of one of the screws etc). Earlier post mentioned its the IAC is directly opposite throttle cable, so I think this answers the "which one" question, but how do you approach this access problem. Remove the throttle body? Will I need gaskets or anything? Remove the injector bar? Carbs are a bit of a new area for me, and haven't really messed around with cars in general for 25+ years, so would really appreciate any hints tips as a little bit reluctant/concerned/scared !!! Thanks folks

Edited April 7, 2018 by WGC_Bloke
added car model info

[ColinBarber]

You should clean the butterfly by spraying carb cleaner on a rag and wiping it. You should remove the throttle position sensor or throttle motor.

Have this just happened? It could be something like a faulty temp sensor or some other issue causing the high idle.

The following is a diagram of the throttle body

[WGC_Bloke]

That's great - many thanks. I was hoping the butterfly wasn't shutting properly, so have already cleaned that out till its gleaming. This would not however, explain the achievable low revs when driving. Oddly, in desperation, I sprayed everything with WD40 - hoping some would seep in somewhere. After about 15 minutes idleing, while I screwed back the air filter box, and pondering, the idle speed dropped from about 1 3/4 to just 1/2-3/4.

I'm wondering if

1) the long shot WD40 had an effect
2) the ECU reset I done a few miles/days ago had "learned"
3) it was just a case of warming up (but ive never known it to idle this high or for so long after a Battery disconnect)

Anyways - thanks for the tips, I think I'm sorted now (apart from the screwdriver bit now wedged behind a carb blanking plate !!!!
And that, will just have to stay there!

 

Cheers

 

[ColinBarber]

Normally If the ECU just needs to learn the new idle point then I recommend getting it up to temperature and then whilst driving come to a complete stop and let it idle in neutral for 10 seconds then drive away and repeat. The ECU will lower the idle each time by a small amount unless it settles at the correct speed.

Letting it idle for a prolonged period should also correct - which seems to have happened in your case