Removing cats, tricking ecu

[Lionsp38]

Hello. I have a 2000 p38 and i had to remove my air injection the fun way (reciprocating saw) to deal with a plug which was tending to cross-thread; problem is that now my computer is registering the lack of fresh air into the exhaust under cold-starting conditions as the second set of 02 sensors (post-cat ones) are not seeing the correct operating of the cats, until fully heated and so i get a check engine light after 2 cold starts (air injection only functions then). Does anyone know if using a resistor to give a solid .5 volts feedback to the ecu will cause the computer read the cat ok or will it notice the obvious trickery due to the non-fluctuating signal since it would be a steady .5v? Any help appreciated. I am hoping to get the faultmate for my birthday in the fall, maybe i can set my ecu as a euro version that does not registed the post-cat sensors?? I just also want to ditch the cats totally but maybe the system would go open-loop, i dont know...anyone else touch on this last point? I have the motronic system, not the gems. Thanks

[nakedbarra]

A Good source for answers to questions like this is www.rangerovers.net , not to say that nobody here wont know the answer .

[Lionsp38]

Yeah. Its a great site with plenty of info, nothing regarding this issue though; I'm suprised that it is not a more common mod for disco and rr owners to remove cats and air injection....anyone? Thanks

[DaveB]

I'm suprised that it is not a more common mod for disco and rr owners to remove cats and air injection....anyone? Thanks

Most of the folks on the site are down in the lower mainland which has Air Care and thus they can't run without the cats even if they were able to successfully remove them. So in most cases there's no use doing it.

I know a few guys up here (Okanagan) remove the cats or put headers on their vehicles with no plugin for the sensors, but I'd want to be working with someone who really knew their OBDII (or whatever system your on) to ensure they'd be able to make a setting adjustment that will trick them.

Really, it's not a very popular option in these days of environmental concern. Why not just get new (or good used) cats and do a bit of porting work to make their entrances more efficient, and a good free-flowing cat back exhaust?

cheers, Dave

[Lionsp38]

Thanks Dave, I really don't mind the cats and you are correct about the environment, my main issue really is dealing with tricking the post-cat sensor feedback to eliminate the check engine light which I have due to removing the air injection... Headers, that would be nice!