I got a 1987 Jeep Cherokee Laredo that was sitting at a ranch for a few years. It's a manual transmission that runs well. I've done most all the basic tune ups (oil and oil filter change, fuel filter, spark plugs, cap and rotor, and changed the air filter), but it is still far from passing emissions. What else is there that could be causing this.
4 Liter straight 6 cylinder engine
What did it fail for? Any idea how old the O2 sensor is?
That engine will have the "Renix" (Renault/Bendix) fuel injection and engine management system. Although not specific to emissions there's a lot of information here on dealing with that setup and it's possible that electrical problems detailed may be playing a part in your emissions problem:
https://www.cherokeeforum.com/f51/cruiser54s-mostly-renix-tips-153657/
Well old age especially but generally it's fuel injection problems that they sit in the fuel injectors are dirty Don't spray right try pressure cleaning them first. I just realized when they're that old sometimes the catalytic converters I just shot and need replacing
