2.3L ('83-'97) Check engine light

[craig]

My 97 b2300 has a check engine light stay on after my mechanic rodded out my cat it also has a glass pack muffler. And a 2.3L engine. Problem now is that the computer is put the engine in limp mode it is hard to drive around town with the ac on, it has uneven engine idle and I’m guessing poor mileage. Wondering if there is not a way to tweak the computer so it will perform better without the cat thanks Craig

 

[pentode]

Was the cat plugged or were you looking for more performance? I hate to say it but I think it's probably more expensive to either buy the gear to tune it or have someone tune it than to just put a cat back in it. I'm not even sure it's possible to get the computer to ignore the downstream sensor and I don't think there's much performance to be gained anyway. If you want to run it without a cat, my guess is it's going to be an ongoing project trying to get it running right. Maybe someone here knows more about tuning that particular ECU.

You should be able to megasquirt (or other aftermarket computers) it but that's an even bigger project.

 

[craig]

Yes the cat was clogged was told an engine performance improves without one

 

[pentode]

In theory, the more free-flowing your exhaust is the more power you make. In practice, these engines are finely tuned to work as designed, there's not a ton to be gained without some pretty serious mods, and the computer is in charge of everything. With no cat in it it's going to be seeing the cat isn't working, trying to protect it from melting down and freaking out when it fails and going into safe mode.

The short version is its probably easier and cheaper to make it run with a cat than without one.

 

[Curious Hound]

What are the codes? Are you positive that that is the problem or the whole problem? What happens if you unplug the downstream sensor? What happens if you remove it from the exhaust but leave it plugged in electrically?