1989 XJ Throttle issues on startup. - Jeep Cherokee Forum
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1989 XJ Throttle issues on startup.

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Old 06-17-2017, 06:27 PM   #1
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Default 1989 XJ Throttle issues on startup.

Hello, I'm new here and I had purchased a Jeep about 6 months ago from my mom, been putting some work into it since then but I've been having one major issue that has been bugging me.

Whenever I start it, it takes a while to crank (If it hasn't been run in a few hours) then it will idle fine for 15 seconds or so, then the motor will bog down to a sputter, then rev back up and repeat this process 2 to 4 times, sometimes stalling.

Once I start driving, the same issue occurs when I attempt to give it throttle, it will bog down to the point of almost stalling (Sometimes stalling) then rev right up.

This all goes away after driving it for about 1/4 mile, after that it throttles fine and runs great.

Any help you guys could give me would be greatly appreciated!
Here are some notes

- There is a fuel smell when it revs up after almost dying out
- I"ve already replaced several parts on this jeep, I did all new Vacuum lines,(Old ones particularly after the intake were nasty and broken) new harmonic balancer, new plugs, wire, cap and rotor.
Supposedly the IAC is only 2 years old as well.

The problem existed before changing all these parts and is still persisting, it seems to be getting worse at a very slow rate.

I will try to get a video of it and post it here later on.
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Old 06-18-2017, 07:16 PM   #2
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Welcome.

We will get this figured out.

To begin with, go to www.cruiser54.com and perform Tips 1,3,4, and 5.

Make sure your intake manifold fasteners are snug.

Inspect the tube from the throttle body to MAP sensor closely.
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Old 06-18-2017, 11:37 PM   #3
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Thank you for the reply! Hopefully tomorrows weather holds out and I can get going on those tips, for now here is a video of it happening on a cold start

https://www.youtube.com/watch?v=A1VT...ature=youtu.be

Note that the vehicle is doing everything on it's own after it is started, I gave it no throttle in this video.
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Old 06-19-2017, 08:21 AM   #4
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Quote:
Originally Posted by typh3621 View Post
Thank you for the reply! Hopefully tomorrows weather holds out and I can get going on those tips, for now here is a video of it happening on a cold start

https://www.youtube.com/watch?v=A1VT...ature=youtu.be

Note that the vehicle is doing everything on it's own after it is started, I gave it no throttle in this video.
Get on the other initial Tips, but do Tip 11 in the meantime.
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Old 06-19-2017, 07:04 PM   #5
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Weather didn't hold out for me to finish all of them (No garage, thunderstorms) however I did finish 11 first, and the IAC and throttle body were surprisingly clean. I got about halfway done with 3 and I cleaned the ground for 1.
Do you have any suggestions as to how to get in there for number 1 to remove it? There isn't alot of breathing room and the bracket that holds the dipstick tube is really in the way, can I just remove that temporarily or no?

Also, the ground stud for number 1 was so gunked with stuff I couldn't even find it at first... Several of my gaskets are bad too so the motor is quite dirty.
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Old 06-19-2017, 07:09 PM   #6
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At the dipstick tube stud, hold the stud still while using a 1/2" wrench to remove the nut.
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Old 06-20-2017, 01:52 PM   #7
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My 1987 does that also, it's worse if it sets for a couple of weeks. I have a wide band air fuel ratio guage on mine and what I've seen is that the engine control will mess around with the fuel mixture. It will start and then will start to lean the mixture all the way to the point of no fuel (stalls sometimes) and then start to add fuel to the point off full rich. I can watch the gauge sweep from lean to rich if I do not touch the throttle. To me it seems to be learning. I don't know if some modifications I have done to the ignition system cause it or because my engine control is getting its reference from the 5 volt wire on the wide band O2 sensor.
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Old 06-20-2017, 09:06 PM   #8
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Almost done with all the tips, I did 11, 4, and am almost done with 3 and 1, 5 is on the list too.
All I have to say is wow, these things are far more helpful than I thought!

The light connector on the drivers side was just as bad as the photo on your site, and I'm eager to see how it reacts tomorrow on a cold start.

The only thing I have left on 3 is the connectors near the coil from a line that goes directly from the positive battery terminal, I'm not sure what it is (It's in the relay center) but those connectors are in very very bad shape... So I will probably get that done in the next few days and finish up the grounds.




The coil had some corrosion on it so I cleaned it up real nice...
Here's what it looked like
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Old 06-20-2017, 11:03 PM   #9
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Yikes!! You are the poster child for what needs to be done and how to get after it!!!!
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Old 06-21-2017, 11:20 AM   #10
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Im curious though, that highly corroded prong in the center, what exactly is that for? There isn't anything that attaches to it, is it supposed to be that way? I clearly saw where the other two round prongs go but the flat one just kind of sits in the open with nothing attached to it.
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Old 06-21-2017, 02:09 PM   #11
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Quote:
Originally Posted by typh3621 View Post
Im curious though, that highly corroded prong in the center, what exactly is that for? There isn't anything that attaches to it, is it supposed to be that way? I clearly saw where the other two round prongs go but the flat one just kind of sits in the open with nothing attached to it.
I believe that Renix ICM/Coil was used in multiple applications worldwide.
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Old 06-29-2017, 05:08 PM   #12
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Hey! Been off for a bit since I injured my ribs, but I finally finished all the steps (Minus number 5, my multimeter broke and I haven't gotten a new one yet)
I have noticed improvement in various areas, alot of those terminals were bad. The relay center connectors were a disaster, but I used a wire brush, some cleaner and oxguard and went to town.
I'm still having the startup issues though with the throttle and stalling, I was told a while ago it was fuel injectors but I don't think that is the case since it would be more consistent if it was and not fine after driving it for a quarter mile.
I am however going to be replacing the fuel filter soon... I don't know how old it is so it's on my list, I just can't lay down too well right now due to my injury, hopefully in the coming weeks I can get more done.

Any more possible insight would be well appreciated
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Old 06-29-2017, 05:14 PM   #13
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Quote:
Originally Posted by typh3621 View Post
Hey! Been off for a bit since I injured my ribs, but I finally finished all the steps (Minus number 5, my multimeter broke and I haven't gotten a new one yet)
I have noticed improvement in various areas, alot of those terminals were bad. The relay center connectors were a disaster, but I used a wire brush, some cleaner and oxguard and went to town.
I'm still having the startup issues though with the throttle and stalling, I was told a while ago it was fuel injectors but I don't think that is the case since it would be more consistent if it was and not fine after driving it for a quarter mile.
I am however going to be replacing the fuel filter soon... I don't know how old it is so it's on my list, I just can't lay down too well right now due to my injury, hopefully in the coming weeks I can get more done.

Any more possible insight would be well appreciated
Stick with the plan.
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Old 06-29-2017, 07:46 PM   #14
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If the idle cycles every 10-20 seconds or so, almost dyeing then reeving a little after, your 02 sensor is likely among the things that need attention. You might hit it with PB blaster or liquid wrench or something now and then while you are sorting out the rest, first.
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Old 07-03-2017, 10:08 AM   #15
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Okay, so I am finally finished.
I refreshed every ground and electrical connector I could find, used an electronics cleaner on em, wire brushed what needed to be and oxguarded everything.

Dipstick stud, firewall ground, ect all brushed down to bare metal, cleaned all wires and reattached with oxguard.

ICM contacts and all associated connectors have been brushed, cleaned, and oxguarded.

Map sensor to throttle body hose is in relatively good condition, it's a bit dirty on the exterior (Seal leaks, the entire inside is dirty) but the hose isn't rotted and neither are any of the fittings.

Throttle body and IAC got all cleaned as well, those were in relatively good shape before and it didn't seem like it needed to much, went ahead and did it anyways.

Now comes the (Tricky?) part.
When I went to check the sensor grounds for tip 5, my meter measured a steady 4.7 Ohms.

When wiggling the harness it it stayed between that and roughly 5.3, it spiked to 9 at one point but I think I had moved one of my leads improperly at the time.

While I'm not 100% sure how accurate this is (My multimeter is old, and when I did the ground check by touching the leads according to the manual I got a resistance of 2 instead of 0)

With all that moving along, the Jeep still has the problem it had in the video I showed before, however there have been various improvements in other aspects since doing all of this.
The most noticable is it seems my starter is far more aggressive than it was before, it is cranking faster and starting faster as well.

However the issue with the idle and occasional stalling post startup still occurs.

Let me know if I missed anything, and what should I move onto next?
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