Help me interpret this WB o2 reading

[axl911]

Hi all,

I have this annoying loping idle in my 3.6 which I think is an vacuum leak and is chasing down. I've cleaned/replaced the O2 sensor, MAF, and ISV so these components could be ruled out. Engine also has new cap + rotor. Wires were done not too long ago.

Anyway, I have a wide band O2 that I can move between two heat exchanger header banks before they merge at the cat.

On the left side, I see bouncing AFR from 14.2 to 14.7.

On the right side, I see bouncing AFR from 14.7 to 15.1.

If it is an vacuum leak then the leak would be on the RIGHT side correct?

thanks,
anthony

[Bill Verburg]

Originally Posted by axl911

Hi all,

I have this annoying loping idle in my 3.6 which I think is an vacuum leak and is chasing down. I've cleaned/replaced the O2 sensor, MAF, and ISV so these components could be ruled out. Engine also has new cap + rotor. Wires were done not too long ago.

Anyway, I have a wide band O2 that I can move between two heat exchanger header banks before they merge at the cat.

On the left side, I see bouncing AFR from 14.2 to 14.7.

On the right side, I see bouncing AFR from 14.7 to 15.1.

If it is an vacuum leak then the leak would be on the RIGHT side correct?

thanks,
anthony

14.7 is stoichiometric, less than that is rich, more lean. Too much air makes it lean. leak if any is on the right

[axl911]

Thanks Bill.

Do you know what the AFR reading will/should be if I disconnect the O2 sensor and let the car run in open mode?

This is a late 95 US car, so I don't think there is a CO variable setting on the car.