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Halp! My Cherokee is Dying

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JeeperJolene View Drop Down
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    Posted: Feb/21/2018 at 7:08pm
I've been having starting issues with this thing for a while. My 2000 XJ has a heck of a time starting when it's cold, but when it's warm out it fired after a few cranks. However, I'm starting to have idling issues. Here are the scenarios:

Engine cold, weather cold: Can take up to four tries of three or four cranks for it to fire, has a subtle idle rumble
Engine warm, weather cold: Idles like crap
Engine cold, weather warm: Starts up after two to three cranks
Engine warm, weather warm: Starts up, but then struggles to even keep 200 RPM and amount of throttle makes no difference.

If I can get it moving and rev it up, then it will balance out and run until I shut it off and repeat. Here's a video of it:



Because of the below-freezing temps at the time that it started, I took it to a specific dealership because a few people I know recommended them. Big mistake. They "fixed the timing" which did nothing. Luckily they didn't try to charge me for it. when I questioned them, they just said "it's time" as if I'm going to buy a new car from them.

Other things I notice:
  • The charge meter is always hanging at 13 volts and can sometimes drop to ~12.5 if I turn the heater on.
  • It definitely feel sluggish sometimes
  • It's harder to start if the heater was left on

Any ideas where I should start poking around? There's no tapping or odd sounds using my "stethoscope". Oil and coolant look okay. The fuel injectors are all working and the fuel pump is new and working fine. I really don't want to pull the cam out since it's still cold outside, but I'm starting to think I'll need to.


Edited by JeeperJolene - Feb/21/2018 at 7:11pm
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billd View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote billd Quote  Post ReplyReply Direct Link To This Post Posted: Feb/21/2018 at 7:18pm
The injectors are working -but how well? How many miles?

Should be charging closer to 14 volts but be wary of the accuracy of the built-in volt meters!!!
It should charge around 14 and maybe drop to 13.5 or perhaps a bit less at idle with a load like heater, headlights and so on.

I noted that the computer for my 4.0 in my Eagle didn't kick the MIL until the voltage dropped below 12 volts - I had a blown fuse in the charging system and was running a couple of days just off battery - and FINALLY the computer kicked on the light. By that time I told it "WELL DUH!!"   Ha, I actually did yell at it for waiting so long. 

unless it has a bazillian miles and no oil changes, why suspect cam?
You can check the cam by pulling vale cover and watching the push rods, and using a dial indicator and seeing if the valves open as much as they should. Don't pull it apart without measuring things first - you may find it a waste of time. You can check for worn lobes with simple tools and a couple hours of time. 
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JeeperJolene View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote JeeperJolene Quote  Post ReplyReply Direct Link To This Post Posted: Feb/21/2018 at 7:21pm
Newly rebuilt injectors. Maybe 800-1000 miles. I had the issue before replacing the injectors as well, but I will say that going from one to four hole injectors improved the fuel economy a little before this issue became really bad.

The reason I suspect the cam (or worse) is the previous owner. I bought this a few years ago and the engine was just full of crud. Apparently the 331 head cracked and they just pulled it off and replaced it with a head out of a 99 WJ. I spent hours cleaning that block out of rust and he definitely didn't understand what the words "oil change" meant. I knew the engine would eventually bite the dust but I was hoping for a little longer. The Cherokee has about 192K miles.


Edited by JeeperJolene - Feb/21/2018 at 7:35pm
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mixed up View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mixed up Quote  Post ReplyReply Direct Link To This Post Posted: Feb/22/2018 at 12:43am
are there any codes showing post the numbers or look online for the reason thing that come to mind are mass air flow or could be a temp sensor gone bad might want to try cleaning the mass air flow first with those miles if you can get a scanner it will help you in your diagnostics try disconnecting the mass air flow see if that changes the way it runs with todays computer control it could be any thing
69 amx 290 auto
65 220 290 4spd
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Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: Feb/22/2018 at 7:04am
Lots of things it could be. As Billd asks... how many miles does it have on it? Have any of the sensors been replaced? The main one I'd think of is the CPS on the bell housing. If it's going bad that affects timing and cranking. The computer has to get a clear signal from it. If I were just replacing parts that's the first one I'd replace, but proper diagnosis first!! As mixed up says, any codes?

You could just have a weak battery since this happens when cold more often than warm. Check the battery while running with a volt meter on the battery posts. Should be 13.7-14V, then cut lights on and see how much it drops. As Billd says -- 13.5 or so, but not all the way down to 13. If it's dropping that much and the battery is 4+ years old, I'd replace the battery then check again. If still not charging it's likely the alternator, but pull all the connections on the back of the alternator and clean first. Clean the battery terminals, and the other ends of the connections also, and both ends of the big wire from the alternator (IIRC it goes to the starter relay). You might even change the battery cables and the big wire between alternator and relay. They can corrode inside the insulation and affect charging.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote purple72Gremlin Quote  Post ReplyReply Direct Link To This Post Posted: Feb/22/2018 at 7:35am
Hmm. The alternator charging? How about fuel pressure?
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JeeperJolene View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote JeeperJolene Quote  Post ReplyReply Direct Link To This Post Posted: Feb/23/2018 at 5:42pm
I think I figured out what it is. If I confirm my suspicion, I'll update the post with what the issue is, what caused it and how I fixed it.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: Feb/24/2018 at 7:48am
MY Rambler (with 89 Jeep 4.0L EFI) totally died while out one day. Thankfully not far from home. I suspected the CPS was done. While reaching down to unplug it I noticed that the wires to the O2 sensor were against the manifold. One had melted to it and was grounding against it! That was the issue. It's a three wire sensor, one ground, one heating element, and one to the ECM. Don't know which was grounded out, but I suspect the ECM wire. Strange things can happen! A splice and something to hold the wire in place better and I was good to go!
Frank Swygert
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Post Options Post Options   Thanks (0) Thanks(0)   Quote vinny Quote  Post ReplyReply Direct Link To This Post Posted: Feb/24/2018 at 8:32am
My experience with two identical engines is that the one with the higher compression starts better. Maybe do a compression check to see where you are at. 
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