Voltmeter stays the same...right around 14 if I had to guess without looking. Idk, the battery is a few years old but it isn't struggling to start it or anything. This was a fairly sudden issue.

 

Okay.

 

Nice piece of info there.

 

2000 FSM.

Same in the 1999 FSM.

Nice to have DATA.

 

Thanks for all the help...went ahead and ordered 2 02s so gonna start there. Will keep this updated.

 

Question since I'm gonna try and pop these bad boys on Sunday more than likely...do I need to reset the computer after? The cables will be off while I'm working on it but I know holding the ends together clears it out right? Or what is it that clears it?

 

Here you go for the procedure

http://www.quadratec.com/jeep_knowle...article-89.htm

 

Mini Update:

Got the upstream one on tonight...came off really easy. The downstream one...not so much...got it soaking in some stuff overnight hoping it will break loose tomorrow. Ended up breaking off the CCV? I think (valve closest to the radiator on the valve cover) so I gotta figure out how to get that off and find a new one. Haven't started it up as I wanted to wait until I got both on but idk if I can get the downstream one off. Also, the nasty rattle I thought was coming from the cat...I think/hope was just the upper heat shield...I noticed a weld was broken and Dad looked at it and said it was hitting the cat and bent it back so it wouldn't so I hope that was all it was. Will update tomorrow about the 02 stuff though. Now searching the forums about the CCV or PCV or whatever that is, lol.

 

Advance auto sells what you broke along with the rubber grommet.

Grommet part number - Help! 42344

PCV Elbow part number - Help! 47057

Careful with those 02 sensors. I heated one up with a torch not too long ago and it came out with ease. Looked at the threads of the 02 sensor and realized they were stripped. No biggie. Wrong. Turns out the bung threads stripped out as well.

Had to pull the downpipe off the jeep, cut the old bung out, grind out the hole, weld in a new bung. No fun. Try to avoid that.

 

The CCV (elbow with the tiny orifice) should be the one near the back of the valve cover. It should have a smallish tube or hose that runs to a vacuum fitting on the intake manifold or throttle body.........


The elbow towards the front of the engine is the breather, and should have a larger tube running from the air filter box..........


If the engine is healthy, and the system is hooked up properly, crankcase vapors should be sucked out of the engine, and into the intake manifold to be burned with the fuel/air mixture.....................As well as fresh filtered air drawn into the crankcase from the air filter.........


If the engine is worn, and has a lot of blow-by from combustion, the CCV system can't keep up, and it will pressurize the crankcase and push oil into the air filter box through the breather tube..........................


Sometimes the little CCV orifice gets clogged up with oil sludge or gunk, and the system will not function, and you may get crankcase vapors and oil vapor in the air filter box as well.

 

Thanks for the help...I will check into it tomorrow. Honestly, we still couldn't get it out but just left it overnight since it was getting dark. The rear one has some oil leaking from it so I'm sure it needs replacing too. I sprayed some solvent on both 02s and let it sit, then moved it to where we work on them and it heated up a decent bit. Dad crawled under it to take a look and just on a whim trying to get it off and it popped right off nice and clean. Was covered in carbon but I'm sure that is normal to an extent. Downstream is being a b**** though.

The story about the CCV was this...not trying to derail the thread btw but would love some input. Ok, so when I bought the truck it had one of those cold air filters on there with the air box removed and the filter exposed or whatever. So anyway...when I crank the truck you can hear it pulling air but when I put it in gear you can hear a huge wave of vacuum being pulled. You can pop it back in park and it quits...back in gear and it starts again. Lasts for a few seconds and then quits...generally once you start driving...5 seconds tops. Here lately it has been lasting longer...noticeable. To the point where I was coasting to a stop at the driveway and could feel it at a higher rpm and wanting to fight against my braking. Once I stopped and started driving it went away. I HAVE NOT IDEA WHAT THIS IS, lol...any ideas? We were looking around at the lines when I broke the CCV.

 

Yea the breather is what I broke then. I need to replace the CCV at the back b/c it is leaking some oil. Does anybody have the parts for both the breather and the CCV?

 

Yep, that downstream sensor can be a reeeal pita. Mine's still in there...
Upstream sensor is more relevant anyway, apparently.

Breaking the CCV grommet on top of the valve cover while doing the O2 sensors...did you dive in from above or something? Will likely need to remove the valve cover to replace that (and to make sure you didn't drop any of the brittle plastic pieces into the valvecover...

 

No lol We were looking for what was causing that loud vacuuming suction noise and was gonna pop it off and clean it and it broke. It was the one on the front of the valve cover (closest to the radiator)...that is just the breather correct? Do I have to take the valve cover off to fix that one?

 

The factory air filter box muffles alot of the air intake suction noise...............
If you have one of those (Cylinder Shaped) open air filters on it, you will probably hear much more suction noise coming from the throttle body.......

It more than likely changes when you put it in gear, due to the computer opening up the idle air control valve to keep the idle speed constant, and making a different suction sound......


If you are hearing a vacuum suction sound coming from inside the cabin when you step on the brakes, and goes away or diminishes when you let off the brakes, then more than likely you have a failed diaphragm in the brake booster chamber.................
This could also cause your engine to stall at low rpm, like coming to a stop......

In most cases, they fail due to brake fluid seeping into the booster from the back of the master cylinder bore (where the rod pushes in) You would rarely know this is happening unless you suddenly notice a loss of brake fluid from the reservoir, but can't find any leaks anywhere..................
Sometimes you can pull the larger vacuum hose off of the booster, and if there is any trace of dampness in the hose, you have brake fluid in your booster..................................but in most cases you would need to undo the nuts, and separate the master cylinder from the booster to look in there with a flashlight..................

I worked on a customer's Grand Cherokee once..............All they told me was it had a problem with the brakes....................When I pulled the master cylinder, the booster was HALF FULL of brake fluid...............
The owner kept putting fluid in the reservoir, said it had been like this for a few months...........
I replaced both the master, and the vacuum booster, bled the system and all was fine............

The booster diaphragm can also fail from age..................With no fluid intervention..............Or from fuel vapor contamination.......
Some GM cars used to have an inline carbon filter in the large vacuum hose running from the intake to the brake booster chamber to keep this from happening.......
Once the diaphragm starts to go bad, in addition to the vacuum whooshing sound when you step on the brakes, you would also notice a decreased "assisted" feel to the brake pedal, and it would get harder and harder to apply braking force.............