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01 Wj 4.7 P0171 code

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Old 07-19-2015, 07:45 PM
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Default 01 Wj 4.7 P0171 code

Hey guys. Just picked up a used 01 WJ this week and have been working some kinks out.

Put in a new fuel pump and fuel filter this weekend, have constant 58psi now. Still takes a couple tries to get it started though.

The last owner has a pretty crappy exhaust set up on it now. Just Falling apart. The drivers side exhaust manifold leaks too.

She runs pretty rough at an idle but still is able to move itself pretty well.

Should I just throw new plugs and a upstream O2 sensor in it? Or should I fix the exhaust manifold and put a new exhaust system under it before I go any further?

I want to make sure the motor is decent before I put too much money into it. thanks for any help.
Old 07-19-2015, 08:17 PM
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Fix the exhaust. If there are leaks the O2 sensors are getting wrong information to the PCM and causing it to over fuel.
Old 07-20-2015, 08:02 AM
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Fix the exhaust manifold! I had a Monte Carlo go up in flames because a cracked manifold finally split under load on a hill and set the engine on fire. Not a good time!
Old 07-20-2015, 10:08 AM
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I will get the manifold fixed in the next couple of days. What do you guys think I should do for an exhaust? High flow cat to a Magnaflow or something? Do you guys stick with a 2.5" or go to a 3"?
Old 07-21-2015, 07:50 PM
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That was the easiset manifold I've ever taken off! Waiting on the studs and gasket now....

Does anyone know the torque spec on the manifold bolts?

Got new plugs in today and almost finished tightening up my track bar mounts. Hope that takes care of some of the wobble up front.
Old 07-21-2015, 09:45 PM
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Originally Posted by Mrfrost05
That was the easiset manifold I've ever taken off! Waiting on the studs and gasket now.... Does anyone know the torque spec on the manifold bolts? Got new plugs in today and almost finished tightening up my track bar mounts. Hope that takes care of some of the wobble up front.
24lbsft, start in the center and work your way out.
Old 07-23-2015, 06:44 PM
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Had the manifold dressed and got mopar studs and gasket. All put back together. Cleared the code and Took it for a 10 min ride at low speed around the woods (not road legal yet). Seems to run a lot better. Got my magnaflow 2.25 today too. Can start getting that put up this weekend.

Do you guys run a tailpipe over the axle or a turndown before the rear tire? I don't want a tail pipe cuz I'm sure it's just gonna get smashed on the trail, but I also don't want the cab to fill up with smoke from turn down and low trail speeds.
Old 07-23-2015, 10:04 PM
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I run a tailpipe all the way back. My tailpipe is oval, not round, it stays tucked up out of the way pretty well. It's the only oval tailpipe that I have seen on a ZJ. I did smash it once while going down a rock ledge, but fixed it with the handle of my breaker bar.
Old 07-25-2015, 07:23 AM
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Has anyone else has an issue with the 4.7 not starting on the first try? I put a new fuel pump in it and have 58 psi constant. Also a new fuel filter. I'm kinda out of ideas on that one.

Thanks for he help.
Old 08-06-2015, 08:57 PM
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Well I haven't figured out the starting issue yet. The other day she started ticking pretty good when I got home though. I took the drivers side valve cover off on Monday hoping to see a rocker lying in there. WRONG! Timing chain is loose as hell. One of the guides wore clean through. Don't think it slipped timing though. I just got the new chains installed and timed today. I'll be honest, the timing chain on these things are a huge pain in the ***! Hopefully get this taken care of by Saturday so I can get back to the starting troubles. Almost have her "dependable" again. The last owner didn't do much maintenance to it.
Old 08-07-2015, 08:35 AM
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The whole 4.7 is a huge pain in the Keister.
Old 08-07-2015, 10:41 PM
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Well, got the jeep put back together tonight. Sure went faster than taking it apart! Rolled it out of the garage, rod started to knock, then oil pressure disappeared at low rpm. Started to rip the oil pain out tonight. I don't know what the heck to do. Looks like I get to do a rebuild!!! Yay, not
Old 08-08-2015, 06:02 AM
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That's why I like the 4.0. I don't have anything against V8's, but I do about the 4.7. As a matter of fact, I've always owned V8's. Early Mopars and Chevys.
Old 08-08-2015, 07:07 AM
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I got the jeep for $600 so I thought I was doing alright. I've got $900 in parts already. Now I've got to rebuild the motor. Oh well, what do you do, can't change it.
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