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Unread 01-16-2013, 09:44 AM   #16
JS97ZJ
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1997 ZJ 
 
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Quote:
Originally Posted by papitt View Post
Man I drove this over to the gun shop & shooting range this evening and it had another problem .. As I Got up to about 50mph. It began to surge If I let off it ran fine just driving down the hwy. But any throttle at 50 and it just increased about 400 to 500 rom and the drop back down same amount. I'd say it acts like a bad fuel pump but man that would be the 3rd one on ZJ in a year . I've had 3 ZJ's this year .Gave the others to my Grand Kids. I'm beginning to question these ZJ'S But I'd like to have one for myself. P/S, Auto, 4X4, Utility, & just a neat hunting & wheeling ride it's got to live.
clogged cat will give you the surging at 45+ mph. And usually unable to exceed that speed.

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Unread 01-16-2013, 05:56 PM   #17
papitt
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Yes your correct but don't most of those have a noise you heard . Noise like a whish or pressure pushing through a hole not large enough for the pressure to not get out of. But I'd sure rather it was a Cat.
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Unread 01-16-2013, 07:48 PM   #18
papitt
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....
OK My dog ''TACO'' Just wore me out to take him for a ride. He wanted outside tonight. I wore him out. As we had to finish the girls college basket ball game .. 2 points + an - for the hole 2nd half .. Good game .. Taco laid down in the pass side seat. I live out in the country so I either drive the County Road or My Pastures. Tonight was the C/R.
.. So I drove the ZJ for an hour.. It surges at any MPH nOT just 45 .. Starts down at maybe 20 an gets worse as speed increases to 60 or so. Your head will bounce forward and then Back ..... Volts on Battery are at 14 straight up ..Overhead mileage says 9.3 tonight ...CEL was on as I never killed it tonight. Temp never got over 180. I quess that needs to be up somewhat.
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Unread 01-19-2013, 02:09 PM   #19
papitt
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OK Saturday evening So I go get a Bosch O2 sensor ..After installing it the light went off, Jeep ZJ, runs without the surging now.. And my over head has been on 9.2 for about a week but in just one trip of about 3 miles the overhead has already jumped to 9.8 ...
I also changed the fuel filter while I was at it .. Fuel filter I did pour out a lot of rusty type dirt But it's a big filter so I'd think it'd have some in it. But the fuel poured out of witH no problems .. So I expect the filter was good.
..... But after I went & drove it and it ran fine . So when I returned, I stopped & checked the code although the light is now off but it still had code 21 & now code 51 .. Should I unplug the battery to clear the codes or do I now need to look into code 51 for vacuum leaks..
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Unread 01-19-2013, 02:10 PM   #20
papitt
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Wow while at the Zone I checked the price on the fuel pump .. 309.87 Ouch....
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Unread 01-19-2013, 08:07 PM   #21
KoreaZJ
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Quote:
Originally Posted by papitt View Post
...or do I now need to look into code 51 for vacuum leaks..
51 - O2 Sensor Signal Stays Below Center (Lean)
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Unread 01-19-2013, 09:39 PM   #22
papitt
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Originally Posted by KoreaZJ View Post
51 - O2 Sensor Signal Stays Below Center (Lean)
.. Yes but what do I do about it. And won't it better mileage on the lean side rather than on the fat side.
.. Is it a bad O2 or can the vacuum leak cause it to so the lean code. Or do I unhook the battery to clear the codes and check a few days later to see if it's still gone.
... Any one know how to do a home made smoke test.
... An I guess if there is a vacuum leaks .. a lot of them were in the fuel ring around the fuel pump when I worked at Chrysler. Or the gas caps..
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Unread 01-19-2013, 10:57 PM   #23
rcMikeS1990
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Typically people say to stay away from Bosch sensors and to go with mopar
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Unread 01-20-2013, 11:44 AM   #24
JS97ZJ
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Quote:
Originally Posted by papitt View Post
.. Yes but what do I do about it. And won't it better mileage on the lean side rather than on the fat side.
.. Is it a bad O2 or can the vacuum leak cause it to so the lean code. Or do I unhook the battery to clear the codes and check a few days later to see if it's still gone.
... Any one know how to do a home made smoke test.
... An I guess if there is a vacuum leaks .. a lot of them were in the fuel ring around the fuel pump when I worked at Chrysler. Or the gas caps..
Whenever you change out a part that has anything to do with engine performance you should disconnect the battery to let the PCM re adjust itself to that part change. You will also be resetting the trouble codes so you can get a fresh start with the new o2.
You need to check the vacuum at the intake manifold with a vacuum gauge, a vacuum leak in the fuel system will cause different symptoms.

Reset the overhead and manually check your fuel economy for a better idea of what your repairs have done for you.
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Unread 01-20-2013, 06:04 PM   #25
papitt
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.....Well Guess what .. It did not FIX IT. Dang I got into it this evening after getting me some more gas to drive around with.. Cranked up an No CEL Great .. Drove about 10 minutes maybe 15 .. Then I was pulling a hill added load and was trying to speed up.. It starts the same old pitching it had had in the past. RPM's going from 2250 to almost 3 grand and back down in maybe 2 seconds .. Dang I was sad.
... NO CEL at least but I've not cleared the code by unhooking the battery.
... I did clear the Overhead this evening as I 1st went for a drive . It ran great for about 5 minutes .. It started at maybe 8 mpg & almost as fast as it could show you a a new avg It was up again .. It got all the way up to about 18 .. I could not believe the change & it was running so good .. Then it starts to pitch and the mileage start to drop. It came back down today to about 13. VERY Strange This is the 3rd ZJ that has whipped my ***. These are such good vehicles but they are tough to get straighten out.
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Unread 01-20-2013, 07:06 PM   #26
papitt
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So I recon I still think I have fuel pump issues since that's the most expensive part there is.
Since I put in a Boosh O2 sensor I wonder if it's bad .. No CEL YET.
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Unread 01-21-2013, 08:02 AM   #27
JS97ZJ
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I don't think that it's the pump. It wouldn't effect the economy like that. It would give you more of a performance problem.
It sounds like it might be an intermittent electrical problem. Have you gone through ZeeJay1997's 12 things thread?

http://www.jeepforum.com/forum/f13/1...talls-1407423/

List everything you've done so far so we can follow.
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Unread 01-21-2013, 08:59 PM   #28
papitt
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Ouch ... Well tonight I unhooked the BATTERY I recon I reset the codes..Or say Reset the CEL. I left the battery cables off for about 30 minutes and went & drove A Grand Son's Birthday present ..1995 long whit cheby 1/2 4X4 extended cab TR. His Birthday is Last of May.....
.. So as I got back I Replaced the battery cables and reset out to drive the ZJ .. It ran better but not perfect .. After about a Mile I reset the over head. And the mileage on overhead began to go up .. ''TODAY'' the mpg overhead stayed up at about 18+ 19.2 was the best. Does this model 1995 need to RELEARN .. The computer .. like later models.
.. Tonight the mileage stayed up .. and as I read the codes while I got back close to the house. I stopped and read the codes .. 12 & 55..... great this is after the battery unhook .........................
I really wonder if this is the reason that people say DON'T USE THE BOOSH O2 sensors ..
That people don't reset the CEL by Unhooking the battery. Now I'd say my CEL codes are correct..
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Unread 01-21-2013, 09:27 PM   #29
JS97ZJ
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What your doing is resetting everything that the computer had stored in it's memory.
The PCM will adjust itself for as many variables that it finds and will try to compensate for parts as they wear out. Up to a certain point. Then it will start throwing codes.
When you replace a defective part, it's memory is still set up to perform as if it wasn't change.
Disco-ing the battery sets it back to day one, and won't reach it's happy spot for a few days and needs to be driven through all driving speeds, including cold starts.
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Unread 01-22-2013, 09:51 PM   #30
papitt
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... Well I drove it again tonight The Over Head has settled on about 17.2 mpg.. Now I'm impressed with that. Voltage for the last 2 nights have stayed on the positive side of 14. As It had gone to the Negative side of 14 when the o2 Sensor went defective a few nights ago. That voltage drop is only the width of the needle. I can't think that is anything to watch. Sorry but I think it's still 14V.
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