Has anyone ever used or considered O2 simulators in their cars? What do you do for O2 if you do a cat delete?

 

I believe that you need a tune and code it out... check VelocityAP tune

 

The O2 simulators I saw on line were made to replace the real O2 sensors. The provide a current to the ecu to replace the current provided by the real O2 sensor. If these simulators work it would seem that should get rid of the CEL. The ecu would read the proper voltage so there should not be changes on the fuel mixture.

 

But to answer your question, I've never heard of anyone using them on these cars, most people want the VelocityAP tune regardless, because it makes such a difference once you've changed the exhaust, so that's the way people tend to go.

 

I've been considering making my own using an arduino board. More of a CAT simulator than an o2 simulator. As I still plan on using a real O2 signal as a input. Shape it using my own DSP logic and then send it to the ECU. Its on a long list of todo items. I hope to get to it some time next year. I've studied the ford OBD2 on board monitors spec and it all seems pretty straight forward.

 

Simulators are usually used on the rear O2 sensor (they delay and smooth the front sensor's output). The rear O2 sensor serves 2 purposes: 1. Monitor cat efficiency 2. (typically on wideband sensor equipped cars) correct front sensor fuel trim. If you have no cats or cats that don't work very well, the simulator gets rid of the inevitable CEL and associated smog check failure. If you just want to ignore the CEL, you can hypothetically program the ECU to ignore the catalyst efficiency monitor instead of using an emulator.

The other reason to use one is if you want to bias your front sensor (i.e. with a wideband sensor, feeding a simulated narrowband output to the ECU). The cat will not work with lean AFRs as there will be tons of excess oxygen. Some day when gasoline is hard to come by and smog check is no longer a thing, this would be an effective way to slightly reduce the rather horrific fuel consumption of these cars.

 

The Velocity AP (and other tunes) prevent the car from running the readiness checks associated with the rear 02 sensors, preventing a CEL from triggering. While this does work for preventing the light from coming on, it's important to understand as it may be an issue for you from an emissions perspective. CA, CO (maybe others as well) evaluate readiness checks as part of the emissions check process. I recently found out that if even one check has not completed, the car will not pass. In my case, I had to put the stock cats back in my car, complete all readiness checks, and then get my emissions check done.