As my car warms up at idle, the EUGO slowly creeps from about 13 afr to full scale lean (past 18)

If I blip the throttle, or drive along on part throttle is barely registers on the gauge, occasionally flashes about 16-17.

The car smells like it's running very very rich too, and it's running rough, which suggests to me the ECU is seeing the lean signal and further trying to richen it by pouring in fuel.

On WOT it's fine, and the AFR pops from fulls scale lean to 12-13 where it should be.

Anyone seen this before? It just seems odd that if it's failing, it works ok on WOT but not the rest of the time.

 

you really have to test the sensor..
[media]http://www.youtube.com/watch?v=1mb4VmDd0ao [/media]

thats the best way to test it.

also, if you have exhaust leaks before the sensor it can make it slow.

 

Sounds very much like an exhaust leak

 

Thanks guys.

I had seen the UEGO video a few days ago, but haven't got around to testing it yet.

Agree on the leak, nightmare trying to find it though as the whole manifold etc is all insulated!