Sensor after the catalytic converter

[silveR]

Tried to search for the info but couldn't find anything. On my JDM imported 1983 Trueno there's a sensor attached to the back of the converter, just after the shell. It looks an awful lot like a temperature sensor of some kind with a longish sting pointing across the converter. How does this affect the ECU's operation, is it for cold starts or something? I'm taking off the converter for inspection since it's not mandatory for such an old car here, but will the ECU think my converter is broken and somehow alter the maps or make an error signal?

[banpei]

That should probably be your lambda sensor... It does affect the ECU operation and probably will increase fuel usage. It's not the same as a cold-start injector: it monitors the exhaust gasses and refines the fuel mixture. It's best to keep it there to have the engine operate normally or replace the ECU to a non-lambda ECU (standard EU is without lambda) as well.

BTW: you can remove the catalytic converter and keep the sensor by buying this decat pipe:
http://www.neweraparts.com/Default.aspx?...ductID=168

[silveR]

banpei Wrote:That should probably be your lambda sensor... It does affect the ECU operation and probably will increase fuel usage. It's not the same as a cold-start injector: it monitors the exhaust gasses and refines the fuel mixture. It's best to keep it there to have the engine operate normally or replace the ECU to a non-lambda ECU (standard EU is without lambda) as well.

BTW: you can remove the catalytic converter and keep the sensor by buying this decat pipe:
http://www.neweraparts.com/Default.aspx?...ductID=168

There is already one lambda sensor in the secondary branch of the exhaust manifold that came with the car. I've only seen secondary lambdas that monitor the converter's function on OBD2 cars so far, but perhaps the Toyota engineers have been ahead of their time. Still the sensor and it's positioning look more like a pyrometer sensor to me, but might well be a secondary lambda for that matter.

Hehe, our family owns a racing exhaust factory in which I've worked since I was 14, so I think I can handle the positioning of the sensor myself as well... Thanks for the tip anyway. I've just made a temporary decat and unplugged the sensor, will go for a test drive and see if it made any difference.

[banpei]

Hmmm... Did some more searching on the forum and found this old (dusty) topic:
http://www.aeu86.org/viewtopic/ae86-oxyg...p___/t/613

Looks like there is indeed an oxygen sensor on the cat. So follow the wire and find out if it is connected to anything.

[parrot]

On the Jap instrument cluster is a little light that sort of looks like a cat con with a heat haze. The sensor is connected to this, and is intended to advise you of when the cat con is up to operating temp. Before it reaches temperature, it doesn't work effectively and the light is there to make sure you drive 'appropriately' rather than polluting the atmosphere.

[silveR]

Didn't get any light on mine after disconnecting the plug from underneath the passenger seat. The main thing is that it made no difference to the performance.

[parrot]

No, doesn't affect performance, just a warning light.

I have also seen it stated that it is a warning light that comes on if the cat gets too hot. Not real sure why that is a worry.