Temporary open header ODB2, will it damage or even run

98 xj 4.0
ok this is the first time I've replaced the exhaust without also replacing the exhaust manifold. I'm playin hell tring to get the old broken collector/downpipe bolt out of the manifold flange. I've never noticed them tacked on on my other XJs.

It is now 4:30 in the morning and I'm at my work doing this, about 45 minutes from home.
I will have to leave in a few hours to go get my son and take him to his soccer game as well as do some running around today before I can get back here tonight to finish this.

So If it comes to it what could it hurt besides torque, mileage, and my ears if If I have to run it as is? Will the computer even let me drive normally without any O2 sensors hooked up? or maybe plug back in and dangling close to exhaust stream? They were 180,000 miles old anyway I assume and both were throwing a code before I started this?

Plaese, someone else has to be up about this time. Also any hints on the bolts. I'm grinding away the head and tack weld and pounding them out. the bottom one is starting to cooperate but the top is impossible to get to on my short time frame.

oh and "tack welds" are actually halfway around the bolt heads. bolts already broken off. bottom one came out. and Jeep is on a lift.

well I guess I just needed a break. got the bolts out. Now I just gotta get my walker gasket piece too fit and I should still be ok on time.

It should run, loud as &#@$, but it should run. My '00 started up and ran just fine when I swapped manifolds, no exhaust system, O2 unplugged, made the neighbours angry ... but she ran and idled fine. Can't say much on driveability as I never drove far like that ... I would at least throw a chunk of the old down pipe back on with new bolts to direct exhaust awy from anything meltable.

Probably would hurt your wallet more if you got pulled over for it. I agree with trying to direct the exhause away from important stuff too.