Not running any O2 sensors ?

[1-tonxj]

Alrighty . I got my xj running smoothly again the first set of eBay injectors were junk new ones have it running like new ...So the question is what other than possibly lower fuel efficiency would be expected from not running my upstream and downstream sensors . I don't have cat just a straight pipe with free flow bullet muffler . I have two new sensors and a weld on bung with a part that mimicks the cats presence for the sensor to plug into ,but I just don't feel like pulling the exhaust to drill and wejd the bung in . I'm thinking as long as it doesn't run too rich or lean it will be fine it just won't get the best fuel economy which I don't care about with the mega dumpster.

 

[old_man]

What year is your ecu?

I learned the hard way that the most valuable gauge on an XJ to keep it running tip top is an Air Fuel Ratio gauge. It will show you exactly what the engine is doing. The most common crappy mileage cause is that the computer is not running in what is called closed loop mode. It sets everything back to a limp home mode. There are tons of things that can cause this such as a bad engine temp sensor, a bad thermostat (open or missing), a bad EGR, bad MAP, or vacuum leak, or the computer thinking things are bad due to a bad or missing O2 sensor.

 

[maxbraketorque]

I'm surprised it has any drivability without any O2 sensors. Its likely going to run pretty rich in limp mode, and unlike the old days or carbureted motors, you have no means to tune AFR with a MAP-based engine control system, well unless you get the ECU reflashed. I'd run with O2 sensors, but I guess if you are satisfied with how it runs without O2 sensors, then you are good-to-go.

I suppose one thing that should be mentioned is that with the motor running rich all the time, there will be more cylinder wall washdown and more fuel getting in your engine oil. Will shorten engine life, but if its a beater, then maybe that doesn't matter either.

 

[1-tonxj]

I'm surprised it has any drivability without any O2 sensors. Its likely going to run pretty rich in limp mode, and unlike the old days or carbureted motors, you have no means to tune AFR with a MAP-based engine control system, well unless you get the ECU reflashed. I'd run with O2 sensors, but I guess if you are satisfied with how it runs without O2 sensors, then you are good-to-go.

I suppose one thing that should be mentioned is that with the motor running rich all the time, there will be more cylinder wall washdown and more fuel getting in your engine oil. Will shorten engine life, but if its a beater, then maybe that doesn't matter either.

It's a 99 it's dtill got a distributor . It actually appears to choose to run a bit lean like this . I've driven it around the local trails it seems to run well no hesitation backfire or excessive tailpipe smoke without them .

 

[maxbraketorque]

Would be interesting to see the actual AFR.

 

[time2getdirty]

I ran My last xj buggy for 2 years without a MAF.