idle speed problem

[bansheebuzz]

ok the 1uz used from a crown majesta running standard ecu, is in a 2wd hilux mated to the original 5sd manual gearbox. I am running the speed sensor from the speed head and no speed sensor on the box.

If you start the car and let it idle it will start at 1400rpm and idle down to 500 once warm.

If you start the car and drive off when cold, the idle will not reset to 500 until the vehicles speed is at 0km/h ie if you drive down the highway from a cold start and put foot on the clutch it will idle at 1400 even when warm. Once the vehicle speed is at 0 it will idle down and act fine from there on in. Anyone experianced this or know the answer?

 

[Lextreme II]

I will be doing a diy tutorial on how to fix the ISC very soon. I ordered a set of bearings from a local bearing shop and costed less then $10 usd.

 

[bansheebuzz]

the idle speed motor is not faulty, for some reason the ecu is not telling it to idle down until the vehicle speed reaches 0km/h.

 

[deankdx]

mine has started doing similar, i have not worked out a pattern yet, but i dont have a speed signal to the computer, i am using a manual gearbox.

i thought it might be temp related? seems if it idles for a while it does eventually settle down. i was considering changing the thermostat, any tips on what the go is would be good.

 

[Peewee]

Mine is *sort* of similar.
If I'm driving along and I put the shifter in Neutral (auto), it will rev at 1000rpm.
After I have stopped for a few seconds, it will come down to 600rpm.

My ISCV is clean, the TB is clean, the TPS is in IDL, all my sensors are working, all the speed signals are working.

The only thing I haven't tried is replacing the bearings as per Lex's tutorial.

I'm not sure if it will work, but its worth a try.

 

[Lextreme II]

I spent over 3 hours yesterday on the ISC. Changing out the bearings, cleaning and dissamble the whole thing to pieces. I think most of the problem is not the bearing or the motor. Most of the problem i found is just dirty parts. This is very common with turbo application. Cleaning all the moving parts should do the trick. I found out a method of un-install the ISC less then 30 seconds.

1. Use a 10 mm socket to take out the ISC plastic cover
2. Use a plier and loose the one of the clamp right under the ISC.
3. Use a screw driver and loose the three screws
4. Rotate the ISC clockwise about 30-40 degrees
5. Unplug the ISC.

Note: Once you rotate the ISC, the whole unit slide right now. Therefore you dont have to take out the spark plug wire bridge. This will save alot of time. Dont forget to clean the ISC housing too.