JstGtnStrtd85

Hello everyone I have a 97 ZJ 4.0 with 250k and running strong. After a 5 yr stay in St. Louis I return to her and she needed some work. I did a basic tune up plugs wires distributor and rotor.. Well it still idles rough the tach says it's idling 500-700rpm. She also seems to bog out on acceleration but than gains speed.I also did a scan and the codes multiple cylinder misfire came up as well as high/low O2 voltage.. Now I have heard and seen some people with jeeps going well into the 400k on mileage. I'm just trying to get her back to where she was before. Any help from you guys would be very much appreciated.

Thanks

Bustedback

Check the fuel pressure.

JstGtnStrtd85

Will do this weekend... Also while under the the vehicle I saw that my O2 sensor in the cat had two wires pulled out.. Would this have any effect on idle or what effects would this cause

Unforgiven

That could have an effect. If the computer doesn't see the correct movement from the post cat O2 it will vary fuel mixture to try to cause a change. How long did the Jeep sit unstarted? I would be concerned about fouled or sticking injectors. Run a good fuel injector cleaner through it with Techron in it.

JstGtnStrtd85

It sat for a few months and upon me starting it up I seafoamed the TB and put some in the tank... Also have ran a restore injector cleaner as well... There wouldn't be a way to rig a hookup for those two wires to see if that helps than buy the O2 sensor if that's the cause..? I'm trying to get it up an running better before my trip to Mt. Rainier for some off highway driving..

Creature85

Splicing the wires back together will work. I'm assuming that they've been cut/worn through of course and not just a connector unplugged.

JstGtnStrtd85

I'm pretty sure the other two are connected to the sensor .. So after work today I'll re attach the wires and see if that will help out with some issues.. Fingers crossed... I'll keep you guys posted..

Steve_UP

I've recently fixed check engine light with rough idle / sputter at ~40mph. Code thrown was for upstream O2 sensor on engine side of cat converter. Replaced it with Bosch part and put $20 in fuel cleaner, including Sea Foam motor treatment, Chevron Techron, and Lucas Oil through gas tank. Worked wonders.

One of these times that happens I plan to rig a bypass to the fuel line so I can run half a bottle of fuel cleaner straight to the engine, bypassing the gas tank. Preferably someplace secluded, where the cloud won't waft into a window.

JstGtnStrtd85

That's very interesting I may have to look into adding more than just one fuel/injector cleaner at one time...

Steve_UP

I was so mad at the time I would have put jet fuel through it to try and make a difference. The fuel line cleaner probably helped out quite a bit, but the biggest difference was replacing the O2 sensor. That being said, my ZJ has a lifetime fuel filter that isn't easily replaced, and I put regular unleaded in my tank, so the every so often use of fuel system cleaner should really stay as a part of my regular maintenance. From my understanding it can only help.

I plan to replace my spark plugs next weekend along with some other unrelated stuff. It's been a few years, I just pulled one the other day, they could use replacement, especially at $5 or less a piece, why not.

Long story short, I'd put lots of different fuel system cleaner in it again under similar circumstances to rule out fuel system deposits and possibly clean out the fuel filter some.

Rakkasan_Jeep

Depending how long it's been since your last oil change, run some Seafoam in the crank. Run it for about 100 miles then change the oil. Cleans all the junk out. You can also use it on the fuel system as well.

Check your plugs and make sure they aren't fouled or dirty. With broken O2's, I've never heard of anyone splicing wiring on then to fix them. I would just replace it with a brand new one.

As well, replace the PCV valve too. Hopefully that should eliminate all your problems.

xxlcherokee

Check the fuel filter and fuel pump

JstGtnStrtd85

Yeah I didn't even try splicing it just said I might as well just buy it and go from there... An the plugs I believe was changed before sitting for a while, but was told that it only had 100 or so miles due to my father buying a new vehicle so would they be ok oh worth changing... Also the plugs look very clean and new... As for the PVC where on the jeep might that be located at ?

JstGtnStrtd85

So just an update to my situation seems things took a turn for the worse when I went to start up my ZJ Friday morning I got nothing it would turn over but not start.. All the instruments on the instrument gage don't work and as far as the overhead panel everything but the mileage works... So if I sit with the keys in it beeps and the fuel light comes on...

Has anyone ever experienced this and have a solution as to what's going on???

Creature85

Check your fuel pressure. As someone mentioned previously it could be a fuel issue.