I did a swap for my wifes brother. 96 Outback 2.5 to 2.2. It ran great in CO and all the way back to WI. Once I hit WI the Cel came on. It still runs fine but it has the P0420 low effeciency of bank 1 of the cat.

 

I've swapped the 02 sensors with some good ones I had. The response times are good but it's running rich. Most of the time its 0.925-0.750 range some times dropping to 0.355.

 

The coolant temp is at 190, temp gauge just under half. I'm going to change the coolant temp sensor today and clean the MAF.

 

What else causes a rich mixture, the plugs are darker than they should be and with the O2 readings confirming it I'm pretty sure that is causing the CEL.

Temp sensor was pretty close 2.73 ohms on the new one, 2.22 ohms on the old one.

 

Adjusting the TPS back about 1/4 from where it was set seems to have dropped the O2 sensor to 0.72 - 0.45 with lows a 0.080.

 

I don't have the TPS adjustment instructions with me in WI.

 

Any thoughts on other things that could be causing it to run rich.

 

I have a new O2 sensor coming.

 

Thanks, Larry

It just may be trying to adjust to the denser WI air.

Still running as if it's in CO.

I'd try a reset and then test again.

 

O.

I've had success with seafoam on the "catalyst below effeciency" code.

 

Perhaps search for my name and seafoam and P0420 to find it.

No Cel back on as of now, I"m going to check the setting on the TPS and will run a can of seafoam through it.

 

Thanks