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post #1 of 13 Old 03-14-2011, 08:32 PM Thread Starter
Hollyhood
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1996 XJ Cherokee 
 
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poor highway performance.

I have a 96 cherokee inline 6. Ill start with the known issues. #1 transmission needs drained and filter needs replaced. recently on the highway its started shifting back n forth between drive and overdrive so im sure thats part of the problem. It also has a cracked header and possibly an exhaust leak. But now on the highway it will not go over 65mph. I held it to the floor for a few seconds and it wont budge over 3500rpms. It seems to still have decent pickup driving in town. Definetly not what it had before. I guess Im trying to figure out what the main part of the problem could be. Im on a bit of a budget and trying to fix one problem at a time. I just changed the oil and replaced the sparkplugs, wires and distributor cap and rotor. any help or advice would be great. thanks.

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post #2 of 13 Old 03-15-2011, 07:30 PM
XJcruiser
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the constant downshifting is because you have 31's on stock gears. Mine does it too. Overdrive is worthless if you are going less than 70 anyway, so I just drive in "3". The speed problem could sounds like a lack of power. Fix your exhaust leak so your O2 sensors can read right and go from there. I would guess next likely problem would be fuel delivery.

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post #3 of 13 Old 03-16-2011, 01:50 PM Thread Starter
Hollyhood
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Well it has never downshifted like it is now. Its doing it on flat highyway. But I'm thinking that's partly the loss of power. I'm thinking the cat is maybe clogged. I kicked it and you can hear stuff rattling inside so I'm going to try to get it off tonight and see if that helps.
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post #4 of 13 Old 03-16-2011, 09:36 PM
Trons
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I disagree with above. I'm running stock 3.55:1 gears on 33's (along with several other people I know) and reaching 75 isn't a problem. I did a camping trip last weekend and ran 60-65 all the way there with out a problem (other then some drive line vibes I'm aware of) and ran that at less then 2000rpm. I got about 15mpg for the trip which I was really impressed with and did not have the down shifting problem on level ground.

I doubt you're having trouble with your transmission filter. It's not a serviceable part on the AW4. AW4 has a drain plug and the research I've done is do a drain/fill 3 times and you've changed out your transmission fluid. This may help the problem.

The manifold crack is also common on XJ's and I'm currently running one that's not that bad, so I'm finding it difficult to find this as a serious problem, unless it's a huge crack.

If I had to guess, giving that you said it will not go above 3500rpm, would be the TPS. You should look into checking that.

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'91 Cherokee Laredo, Stock - Sold
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post #5 of 13 Old 03-17-2011, 05:57 AM
cruiser54
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Quote:
Originally Posted by Hollyhood View Post
Well it has never downshifted like it is now. Its doing it on flat highyway. But I'm thinking that's partly the loss of power. I'm thinking the cat is maybe clogged. I kicked it and you can hear stuff rattling inside so I'm going to try to get it off tonight and see if that helps.
Excellent starting point. Get a new cat on it and maybe muffler, too. Sometimes guts of bad cats can pass into the muffler.
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post #6 of 13 Old 03-17-2011, 06:34 AM
jonathoner
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just to 1up you guys, i can pull hills in OD at 80 if i time it all right. Thats on 35s and 3.73s. Will it let you go over 3500 in 3rd?

98 red xj classic|4.5" Rustys short arm|35" KM2s|cut/hammered fenders|no sway bars|tnt belly pan|welded rear
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post #7 of 13 Old 03-29-2011, 04:24 PM Thread Starter
Hollyhood
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bad to worse...

well I took the cat off the other night and changed the tranny fluid. the cat was totally clogged and was blocking the outlet hole. that problem is solved. runs good like it did before. The problem now is that after I changed my tranny fluid my jeep doesnt want to start. It will crank about 10 to 15 times before it actually turns over. then it runs really rough for a few seconds and idles up to about 2500 rpms and then idles out fine and runs no problem. what iv noticed over the past few days is if it sits over night or for atleast it starts perfect. But if you shut it off and start it again thats when it doesnt wanna turn over. It also puffs some blue smoke when it is idling terribly, almost like its dropped a cylinder. The crack is pretty sizeable on the header. Its down by where the header bolts to the downpipe. Im at a loss right now.
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post #8 of 13 Old 03-29-2011, 04:28 PM
jonathoner
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Check engine light on?

98 red xj classic|4.5" Rustys short arm|35" KM2s|cut/hammered fenders|no sway bars|tnt belly pan|welded rear
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post #9 of 13 Old 03-29-2011, 04:59 PM
93gc40
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Sounds like fuel delivery problem, pump, filter injectors. Also would check o2 sensors. Something caused the cat to plug up. Cracked header probably damaged the sensors which killed the cat.

96 XJ 4.0 / 231 / 3.5" JY Lift/ 31" BFG /.....
93 VT1100 - Harley killer.
97 ZJ 4.0 / 242 / Stock
93 ZJ 4.0 / 2"BB / Wranglers / RIP-Gone but not forgotten.

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post #10 of 13 Old 03-29-2011, 08:22 PM
jebmccall
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any crack in a header is serious. it can cause burnt valves,o2 sensors to read incorrectly and dump more fuel, cause o2s too wear out prematurely. you can find new headers online at auto parts company for like 160 shipped, and its a true header style, which is stronger, and more free flowing. did you put a new cat on?
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post #11 of 13 Old 03-30-2011, 08:44 AM Thread Starter
Hollyhood
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No I just busted that honeycomb up inside cleaned it out and put it back on..
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post #12 of 13 Old 03-30-2011, 12:36 PM
93gc40
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In order to correctly diagnose your issue your need to fix ALL of the Known issues. If the problem is still there then we can start diagnosing.

96 XJ 4.0 / 231 / 3.5" JY Lift/ 31" BFG /.....
93 VT1100 - Harley killer.
97 ZJ 4.0 / 242 / Stock
93 ZJ 4.0 / 2"BB / Wranglers / RIP-Gone but not forgotten.

If it aint dirty, it aint a JEEP, it's just a SUV.
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post #13 of 13 Old 04-11-2011, 04:29 PM
XJforlife
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Mine did the same thing 4 weeks ago on my way from Alabama back to Ohio State. The fuel delivery system is a single line - no return system that is housed in the tank. These systems were suppose to be sealed and waterproof, but after years in the tank, they leak and short. This short causes the system to think you are running out of gas when you have a full tank or to just screw with fuel sending in general. Use a reader at a local auto zone and see if your displaying any codes. If you are, most likely your having the same problem.
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