Where Is The Ecu Temp Sensor?

[humanz 3]

I've done a search and gone thru several threads. Also been going through my workshop manual. Still can't figure out exactly where the ECU temp sensor is. Can someone tell me where to find it on my XU9J? Is it difficult to swap? Will one from a 1.6 work on a 1.9? Anything to be aware of if I try removing mine or installing another?

 

Cheers.

[Anthony 1,003]

It's a blue two-pin plug, that depending on the age of your engine, will either be located on the back of the thermostat housing (later engines) or on a small block to the side of the thermostat housing underneath the SAD (earlier engines). 1.6 and 1.9 ECU temp sensors are identical.

[humanz 3]

What's the purpose of the ECU temp sensor?

 

Why I ask:

I've got some idling problems. Actually, both my mechanic and body work guy say that the engine sounds like it's 'hunting'. I have no idea of what that means, but it sounds pretty bad at idle - not a consistent hum, but like revving between 1000 and 1500rpm. The SAD seems to check out, as the car when cold idles at a consistent 1200, and once the SAD has closed up the revs dip then start to do their up and down dance. I've tried adjusting the air bleed screw,, but no matter how much I adjust the screw the revs stay between the 1000 - 1500 range. My mechanic believes it might be the temp sensor, so I was just wondering what's its purpose and how's it work.

[jimistdt 1]

Basically the ECU temp sensor tells the ECU the temp of the coolant within the engine and adjust the air/fuel ratio accordingly. As I understand it.

[AndyJ 1]

Yeah basically when the coolant is cold the ECU richens up the mix while it is warming up, like you would use a choke on a carburettor'd engine. If its kaput you get the wrong mixture.

 

I'd also check for air leaks in the intake/breather pipework, as thats another common cause of hunting at idle.

[GLPoomobile 958]

I doubt it is the sensor at fault. A faulty sensor will typically fool the ECU into thinking the engine is freezing cold, causing it to overfuel a lot. The engine will then run very rough, if at all (which you can replicate by unplugging the sensor with the engine running), which is very different to the up and down hunting you describe (something we've all experienced in a 205 at one time or another).

 

I can never remember specifically what things cause the hunting, so I won't attempt to offer any advice, just say that I doubt it is the ECU Temp Sensor.