Posted by Mickael Just wondering, can people fake the data sent by the o2 sensor ? i.e: is it possible to cheat the smog test without "knowing a guy" ?

It'd be tough. Very tough. You'd need a signal generator, exact sine wave patterns. Stuff like that. Could it be done? Maybe.

I've straddled the fender of a car that was on the dyno while feeding the EGR valve vacuum for the whole test.

Posted by bandi It'd be tough. Very tough. You'd need a signal generator, exact sine wave patterns. Stuff like that. Could it be done? Maybe. I've straddled the fender of a car that was on the dyno while feeding the EGR valve vacuum for the whole test.

If it a pulse width modulation type input you will need that signal generator but you need to capture first the modulation of a good signal

Posted by bandi It'd be tough. Very tough. You'd need a signal generator, exact sine wave patterns. Stuff like that. Could it be done? Maybe. I've straddled the fender of a car that was on the dyno while feeding the EGR valve vacuum for the whole test.

In the FWD/Performance GM community, RK Sport and some other aftermarket folks were selling O2 simulators to get around having a catalytic converter... Here in NY, though, you've got to physically have the damn thing on the car. You know what's funny is somewhere I read that the things really stop working after about 40k miles.

IDK about estimated mileage before that cat gives up the ghost, mainly b/c it would vary so much based on tuning and how the car was driven, but they do cease functioning rather quick. Especially quick considering the job it's there to do. Essentially, there's x-amount of molecules of scrubbing agent coating the tiny tubes inside the cat, and so many molecules of exhaust react with so many molecules of agent, so the whole shebang gets used up pretty quick (sometimes yielding in choking the exhaust and hurting power/economy).

Oh and did I mention that a cat's operating temp window is extremely small? I.e. it doesn't do anything to clean the exhaust until you've driven for a little while. In winter it may never get up to temp, and int he summer it may well get too hot and lose its functionality. O2 sensors are there to adjust fuel mixture to keep the cat at operating temp, and that doesn't always work very well... Just ask the computer on my dad's '92 GMC Sierra...

Posted by ExploringOhio Essentially, there's x-amount of molecules of scrubbing agent coating the tiny tubes inside the cat, and so many molecules of exhaust react with so many molecules of agent, so the whole shebang gets used up pretty quick .....

Actually the catalyst is not consumed during the chemical reaction, it eventually gets covered in contaminants that inhibit its function. This is why scrappers pay good money for used cats, as they still contain lots of precious metals.

Thanks for the clarification Clutchy.

You don't need fancy electronic simulators to fool the computer when you have a hollow cat. There is a method using spark plug anti foulers. you drill 1 out so the o2 can fit threaded in then thread it into a second 1 then thread tht into your exhaust. this spaces the sensor far enough to reduce what it sniffs but it still gets some and gets heated up. And if I were going to delete cats i'd surely just hollow them so that on a visual check they are still present.


This of course is all hypothetical and I'm not advising anyone to violate the law.

Posted by Phreak480 This of course is all hypothetical and I'm not advising anyone to violate the law.

Did you forget this is UER?

I just don't understand the point of "hollowing the cat" on post-1987 road cars...

Posted by Agent Skelly I just don't understand the point of "hollowing the cat" on post-1987 road cars...

its the whole, when it dies why spend the 800$ if you dont get smog checks

Posted by nostra-YOUPPI! its the whole, when it dies why spend the 800$ if you dont get smog checks

My Cat costs 150.00, so your point was?

Posted by Agent Skelly My Cat costs 150.00, so your point was?

mine is $483, moneybags.