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88 Cherokee running rough, low idle.

Old 09-05-2015, 01:44 PM
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Default 88 Cherokee running rough, low idle.

I have an 1988 Jeep Cherokee with a 4.0L with the AW4 automatic transmission. Recently I did the HO swap because my original engine developed piston slap. I got the engine out of a 91 Cherokee that had 186000 miles on it.

But now to the problem, when I first started it up it ran rough and it almost stalls, along with that it wont rev past 1000 RPM and if you try to romp on the gas it stalls out. It also backfires through the Intake and the Exhaust. Also after poking my head around i found out that Cylinders 1 and 6 fire once and don't fire after that and Cylinders 2-5 have multiple firings. I cant get a decent fuel pressure, it starts out around 5 psi and it eventually goes to around 34-38 psi.

At the moment I've switched coils and fuel pump and its still doing the same thing. One thing I have figured out is that cylinders 1 & 6 both have multiple firings when I'm trying to start the jeep but when it is started they don't fire.

Last edited by Travis88XJ; 09-06-2015 at 02:29 PM. Reason: New information
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Old 09-05-2015, 09:01 PM
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Is this the first time you're firing it up? Sounds like timing is off. Did you set the distributer correctly? Which distributer did you use? The one from the 91 or 88? What about the rest of accessories?

Last edited by rdr8887; 09-05-2015 at 09:03 PM.
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Old 09-05-2015, 09:59 PM
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Yes, first time im firing it up. I set #1 a TDC on the compression stroke, lined it up with the 0 degree mark on the timing cover and put the distributor in so that the tailing edge of the rotor in just departing the #1 cylinder spark plug post. I used the distributor from my 88 and all the rest of the accessories are from the 88. So the only thing that has changed is the engine itself.
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Old 09-05-2015, 10:46 PM
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did you use a punch to line up the timing holes in the distributer? This essentially locks it in place. When you put that clip at 1 o'clock and drop it in, should end up perfect on the bolt hole in the block to secure it.

Not sure if this makes sense or not.
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Old 09-06-2015, 08:53 AM
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Not really, expand a little more on what you are trying to say.
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Old 09-06-2015, 09:22 AM
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See attached pic. Align A with B and drop a punch through. It holds the timing in place during install and should land in the correct location ahead of number 1 post.


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Old 09-06-2015, 09:25 AM
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This video could help as well. Best I've found explaining how to do this properly.


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Old 09-06-2015, 02:25 PM
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I get what you are saying now and my distributor doesn't have any of those features.
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Old 09-06-2015, 02:40 PM
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Then im pretty much useless to you. Lol. Sorry about that. There are a few Renix era masters floating around here. Maybe one of them can chime in?
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Old 09-06-2015, 10:05 PM
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It's all good. I'm just trying to get a lead on what the problem could be or some help with fixing it.
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Old 09-06-2015, 11:34 PM
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Have u double checked ur plug wires?I know it sounds like a rookie move but it happens to us all
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Old 09-07-2015, 08:52 AM
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Originally Posted by Travis88XJ View Post
Not really, expand a little more on what you are trying to say.
Not applicable to your Renix set-up.
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Old 09-07-2015, 06:15 PM
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Plugs have been swapped with a known working set.
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Old 11-25-2015, 06:45 PM
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Going to revive a couple month old thread. Started working on my Jeep again, Its still misfiring on cylinders 1 and 6, no spark and no fuel. Replaced the CPS and the Jeep ran better for a good amount of time but after a while it returned back to how it was running before I replaced the CPS. Anybody have any ideas?
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Old 11-25-2015, 06:48 PM
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Of my Tips, which ones have you completed?
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