bought a ZJ and I'm having a few minor issues i can't seem to work out!

[acousticrawk]

so, i have an interesting story and problem:
About a week or two ago, I went up to east liberty and bought a 98 zj, 4.0l that didn't run and had been sitting all winter. the guy selling it said it would crank but wouldn't start due to no spark (they had just replaced everything in the ignition system from coil to plugs) so he said it was probably the CPS (or CKS as some of you might know it.) threw a good battery in it, and sure enough, cranked great, no start. it was pretty clean, and i got the price I wanted so i bought it and had it towed to the shop my gf's dad uses, to have the TPS replaced. I bought a new battery and dropped it off. the tech went out the next day and "cycled the key several times, thinking the add relay was stuck", and it started right up. and it has started fine ever since then! thats the good news... the bad news is the tranny lines were shot, so I had it towed back home to cincinnati (thankfully i have a AAA premier membership) and i replaced the old tranny ones with some rubber line (just temporary until i can get up and order the factory hard lines.) now, it starts and runs, but there is a slight hesitation from idle until 1300 RPMS or so, and, once the jeep gets hot, it starts to idle a bit rough. the steering and suspension all feel very loose as well id like to ad (it does have whatever transfer case is always in 4x4...sucks, and i will be replacing it soon). it feels a bit underpowered as well. not terrible but a bit. I'm going to clean the throttle body and sea foam it as well. could a dieting TPS cause me to idle a bit rough once warm? Ill be pulling the codes when i go to work today.

Also, Im a manager at autozone in cincinnati on warsaw ave. if your in the area and need parts, stop by and see me, ask for levi, ill take care of you and make sure you get a 10% discount! like to take care of my jeep friends!

[frankensteinxj]

What kind of plugs did you use in it?
I had a civic that had platinum e3 plugs or whatever they are and it sputtered and ran like hell no matter what under 2000 rpms. These plugs were brand new from previous owner the ignition system just didnt like them I guess.
Bought some cheap ngk's and it ran like new.
Just a thought.
As far as the steerin being loose........ Its a jeep get used to it lol
TPS could may need replaced, common thing on em.

[acousticrawk]

yeah and the steering is getting more tight as i drive it (fluid was low and i topped it off) I'm a little concerned about the transmission. i haven't driven it but a few miles and I'm not sure its shifting right... we'll see.

as for the plugs, I'm not sure. ill pull them and run whatever jeep recommends. the problem is, it ides fine when its cold. after its ran for a few minutes it idles really low, up and down a little and sort of rough.

[blazerbrad]

If you haven't put new gas in it yet I would be suspicious of it. Make sure you have fresh gas and run a bottle of injector cleaner through it before getting too far into it.

If it runs fines when cold but acts up when hot that means a sensor is bad. When cold the engine runs what is called "open loop", meaning it is running on a pre-programmed calibration in regards to air/fuel ratios and ignition timing and doesn't really pay attention to any of the sensors. When it's warm it goes to "closed loop" and starts using the sensors such as the O2 to make adjustments in those items to optimize performance. Find a good diagnostic manual that will explain which sensors and controls are only used during closed loop operation to narrow it down.

[itbrokeagain]

I wouldn't usually recommend champion plugs but it seems that is what they run best on.

[acousticrawk]

well, i ran the codes at work. i got 3 o2 sensor codes. I've never known an 02 sensor to cause a rough or low idle though. nothing wrong with champion plugs from my experience in anything. they have been around forever and been making plugs for race cars for years.

[underpowered]

i would not put a champion plug in my mower, let alone my jeep. NGK is what i suggest for it. just personal preference though. Many people run and swear by champions.

and a bad 02 sensor could very well cause the issue sending a bad reading back to the CPU causing what i would guess is most likely a rich issue, which would account for your rough idle. the 4.0 is a great motor, but can be finicky at times with bad sensors.

[cincygman]

Originally Posted by underpowered

i would not put a champion plug in my mower, let alone my jeep. NGK is what i suggest for it. just personal preference though. Many people run and swear by champions.

and a bad 02 sensor could very well cause the issue sending a bad reading back to the CPU causing what i would guess is most likely a rich issue, which would account for your rough idle. the 4.0 is a great motor, but can be finicky at times with bad sensors.

Unfortantely, at least for some people, Jeeps don't run well with NGK's or other thought to be better plugs. Don't know why but they sure do like the stock Champions for some reason.

I'm with B-Brad, get some good gas and run some good injector cleaner through it. My 96 ZJ had a bad downstream O2 sensor but all it seemed to do was turn on the check engine light. no performance issues or idle issues. My 96 seems to idle a little rough at times but never searches ( idle up and down) Sounds more like the throttle body needs to be cleaned and the idle strategy relearned after having a dead battery or no battery for a period of time. At least that's my opinion from over 20 yrs driveability trouble shooting and diagnosis. For what its worth anyway and to some...... not much but that's ok

[blazerbrad]

Originally Posted by acousticrawk

well, i ran the codes at work. i got 3 o2 sensor codes. I've never known an 02 sensor to cause a rough or low idle though. nothing wrong with champion plugs from my experience in anything. they have been around forever and been making plugs for race cars for years.

Makes perfect sense. The upstream sensors (before the cat) would be the ones that affect the engine operation. The downstream (after the cat) is simply there to verify the cat is functioning and shouldn't do anything besides set a code.

[acousticrawk]

so i can disconnect the upstream sensor and if it runs better, in "closed loop" mode, I know that it, correct?

[acousticrawk]

okay... so today i did some things to the jeep:

first i disconnected the upstream o2 to see if putting the jeep into closed loop would help; and it did. it ran like a top. ill be picking up an upstream o2 sensor soon.

second, i noticed the PO removed that cat. its delete pipe into a muffle. illegal i know, but I'm not real worried about it yet unless i need to be to make the jeep run right. I've always been taught that the downstream o2 sensor just measures if the cat is doing its job. at any rate.. will the jeep run poorly w/o the cat?

lastly, i used this video as a guide to adjust my tv cable with a few results:
http://www.youtube.com/watch?v=TH4UV2HrD1w

the results of the tv cable adjustment are; when i tried to adjust the cable as per the videos instructions, i realized, i cannon get all of the slack out of the cable. even with the cable adjusted out as far as it goes,my "centerline" of the cable connector is still about 1/2 inch to far passed closed throttle connection. i drove the jeep with this adjustment and wouldn't get out of second gear. i then pulled over and moved it in smaller and smaller increments until i put it back where it was. shifting into 1-3 but in odd places, then i went with old school kick down cable adjustment method, which involved removing the white clip, opening the throttle wide open with the cable connected, pulled out the slack and reattached the white clip. this netted me the best results as i shifted into OD for the first time!

with that adjustment, its still no good... shift points are off and if I'm going up hill at all it won't come out of second until i let completely off the gas or stop and start again on flat ground. downhill it almost goes through the gears to fast.

on a side note, i believe my brakes are dragging slightly. the rotors are pretty pitted from sitting (not horrible or anything) and under hard braking the be dal gets super soft and the brakes stink... i know the brakes need replaced and I'm not as concerned about them just yet. just throwing that out there.

TIA guys!!!

[acousticrawk]

got the tv adjusted correctly! still shift in the wrong places. any suggestions?

[sarge]

ZJ's had a bad problem with cracked valve bodies. New VB is about 100 bucks and easy to swap . this should fix your shifting issues.

[tjrider]

4.0s with odb2 don't like to run without a cat. The downstream o2 sensor will keep throwing a code. Also, 4.0s will default lean when an o2 code is sent. So put a cat on it first and see what happens. I put those E3 plugs in my tj and it didn't like them. Autolites are the best.