Will a 3.8 o2 sensor cause my car to run rich?

 

Yes, if the vehicle is not entering closed loop, then it will remain rich. If you have the emissions numbers, that would be much more helpful.

Unfortunatly, with emissions, you can't cimply guess how a vehicle is running based on one emission, you need to look at O2, CO2, HC, CO, and NOx (if available) to determine the overall running of a car.

Also, what mods, if anything, do you have done?

 

Mods: Headers w/ EGR (small exhaust leak at head) , k&n cone, ford 2.9 injectors, 3.8l heated o2 sensor.

emissions #s:
25/25 test
CO%: 1.09 allowed- 0.97
NO ppm: 1948 allowed- 1082
rpm: 1734 allowed- 3000
CO+CO2%: 14.5 allowed- 6.0

I changed the converter because of the NO reading, so now it has a high flow cat, and when it was tested the check engine light came on which was an EGR code. I figured the EGR code was set off because of the cat considering the EGR valve is new, but i've got the EGR syloniod ordered just in case. Any thing else i should look into? Oh and i get about 200 miles to the tank with city and hwy mixed....

 

EGR is the place to start. Clean your valve while you have everything apart. Your combustion temps are too high, creating those numbers, and the EGR flow helps to keep them down.

REALLY could use the HC number, but it looks like you're running rich, as you expect.

 

sorry
HC: 116 allowed- 152

 

Seems to me the HC is a little high, but I don't remember my numbers from when I did the sniffer test at school. You're within the limit there.

Might want to fix the exhaust leak and see what happens. Could be your O2 is seeing the air sucked into the exhaust stream and the ECM is adjusting the ratio accordingly.

2_point8_boy will be a better help than I will with this...

 

Try adjusting your timing or adding a lil bit of alcohol to your gas?