I have a 99 XJ with low/California emissions. I am trying to replace the PCM because it was fried out several months ago from an over-voltage issue that has been corrected now. I have a 493AD PCM number but I am wondering if a 493AN PCM will be compatible with my XJ.

I also replaced the exhaust manifold and downpipe because the previous owner had done an awful patch job. The previous exhaust had a precat in-between the upstream and downstream o2 sensors. The new downpipe does not have a cat but stated that it was to all emission regulations in the US for that vehicle. I am assuming that precat was part of the California emissions and not having that cat throw a CEL. Will this new precat prevent me from passing NY inspection? Should I just put an o2 sim in?

 

Are you saying your XJ previously had this manifold?



makes a pretty big difference

 

The previous manifold was a 2 piece with 2 flanges, the new one is a single piece with 1 flange. - Your image did not work

 

Whoops so it didn't. Stupid phone. I've edited my post

 

Yes my Jeep did have that manifold but not those downpipes and Looks like the upstream o2 sensor holes on the manifold were plugged on mine. On my downpipe I only had 1 precat and 2 sensors total.
I also don't see the wires for the additional o2 sensors, could have been removed.

 

So it appears as though I have removed what was left of the Cali emissions and replaced it with the federal emissions. The downpipe had been modified beyond any repair and was useless.
Does anyone have a diagram of the California Emissions wiring harness and the federal emissions so I can find where the other o2 sensor cables may be.
Would I be able to replace the current broken PCM with a federal emissions PCM instead to use just the two current o2 sensors?

 

As long as New York doesn't smog you should be able to switch over to federal emissions no problem. If all you have is an inspection then all the shops will look for is that everything is hooked up.

 

I have a shop that has a federal emissions PCM that I can purchase, Not looking to break the law just trying to get my jeep to pass inspection! Hopefully the federal emissions PCM will not throw any codes, still have the main cat installed.