Idle Speed Control

[jkru]

My is200 has hickups when idling with a warm engine.

I cleaned the air intake valve/chamber wich improved the problem a bit:

If you look at the lever that controlls the engine running speed under the hood it used to automatically move with short bursts. That caused the engine to shake at traffic lights. With the cleaned valve that was immediately gone. The lever does no longer move; but you still feel the car move. Ít's less now so if I.m tired it looks like i'm imagining, but I'm sure it's still there.

What else can I clean?

There is no diagnostics code set.

I read at http://www.autoshop101.com/forms/h26.pdf

that for a set of conditions there is a target idle speed. If the actual speed is off with more than 20 rpm then the state of the iscv (idle speed control valve) is adjusted.

I noticed by taking of the intake of the iscv that no air passes it if the engine is warm. Apparently the leak air from main valve is enough. The iscv circuit does work because if i put my hand on the main intake than the iscv starts to pass air (not enough; the engine stops),

Question: What if the programmed target idle speed is too low? How can I increase that programmed parameter?

[ColinBarber]

By air intake valve/chamber do you also mean the throttle body? The butterfly is a good place to clean.

Once cleaned you may find the idle speed is too high. Once the engine is warn, reset the engine ECU and let it idle for a few minutes to bring it down to the normal 650 rpm.

If you are seeing the throttle move then maybe you have a faulty throttle position sensor or just not set correctly.

Make sure the air con is off whilst checking idle.

[GXE10]

try get a injector clean done.....

i had very rough idel b4..... my cat convertor was overheating

so i went for a injectors clean.... the guy told me that 4/6 injectors were leaking fuel into the engine at idle

after the guy fixed my injectors the idle is much more stable

[jkru]

My car besides petrol runs on liquid propane. gas (lpg)

You can switch.

On lpg it has its own set of injectors. (That makes twelve)

Since It only starts on petrol the petrol fuel injectors are not used very often.

On lpg the engine runs smoothly, without movement or controlling the air valve.

The fuel injector suggestion might be useful.

I took apart the array of petrol fuel injectors. They seemed clean. Since I don't have proper equipment I'll go to the dealer on monday.

[Scorpion]

Injectors have to be cleaned under high pressure.

[ColinBarber]

Question: What if the programmed target idle speed is too low? How can I increase that programmed parameter?

If the programmed idle speed was too low then all IS200s would have the same problem. The way you would fix it would be to get a new ECU.