is there a reason why my car is faster with out the 02 sensor pluged in it runs smother but slower with it pluged it could it be that my computer is from a acura ls

 

could be get the right ecu and let us know if that fixed it. also what motor is it and which ecu type are you using

 

Need more info

 

O2 sensor sends back info so that the ECU can make a good decision on how to adjust for fuel... when it is not in, I am guessing the ECU sees a lean condition and increases fuel.

Overall... I think you need to make sure the ECU is compensating correctly for the O2 sensor feedback... if you run rich, you are wasting fuel... if you run lean you detonate your pistons... either way, your car won't run at its best.

just my $0.02.