[therobesons]

I put in a new thermostate today and now my car warms up like it should, which means it idles like it should but the idle bounces from 1000 to 1200 1000,1200, 1000, 1200 and on and on.

What makes an idel bounce?

Bob

 

[rex2nr]

THis should have posted in the "stock" forum, but I would bleed the coolant. On the thermostat housing, there is a (iirc) 12mm nut at the base of a nipple. Loosen that nut while the car is running. This will allow the air bubbles to escape.

 

[Tiersin]

Mine will do this if my Idle adjustment screw is to open.

 

[downest]

The nipple is on the upper radiator hose's inlet to the head on the older D15/D16 motors. On the newer ones like the Y8, and on the DOHC ZC it's on the T stat housing.

 

[ollie]

I'll answer this one then move it to the appropriate forum.

Ahem:You need to bleed your cooling system.You still have air pockets in your cooling system.

The CTS(coolant temp sensor) is the ECU's way of knowing cooling temperature.It needs this info to help optimize idle and fuel mixture.Whats probably happening is as the warm coolant passes the sensor its getting fluctuating readings because the "cold" air bubbles are also passing by.
The ECU is changing the idle due to the changes in readings from the CTS.
I know run-on sentence,but thats how it came out.sue me! :lol:

Fix:Bleed your cooling system. :idea: