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Silver Lake
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Discussion Starter · #1 · (Edited)
There is no check engine light and clears up when you accelerate. I thought it was plugs/wires, so I did a complete tune -up (cap, rotor, wires, plugs). It made a slight difference but not much. I think it might be a bad fuel injector but I'm not sure on how to tell if one is out or not. Any tips?
 

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Iac
 

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..........
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Travis,
Clean your throttle body and especially around the IAC sensor. Take it out and clean around the needle. DO NOT PUSH IT IN OR PULL OUT, just use some carb cleaner and a wire brush to clean the needle and seat. You'll more than likely need a throttle body gasket.

If it were a fuel injector, you'd have faults for injector or O2 sensor codes for running rich/lean.
 

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Silver Lake
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Discussion Starter · #4 ·
Travis,
Clean your throttle body and especially around the IAC sensor. Take it out and clean around the needle. DO NOT PUSH IT IN OR PULL OUT, just use some carb cleaner and a wire brush to clean the needle and seat. You'll more than likely need a throttle body gasket.

If it were a fuel injector, you'd have faults for injector or O2 sensor codes for running rich/lean.
Cool, I'll give it a shot when I get home. Thanks for the help :thumb:
 

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the 4.0 is a rough idleing motor anyway. what oil do you run it it?
 

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Silver Lake
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Discussion Starter · #10 ·
the 4.0 is a rough idleing motor anyway. what oil do you run it it?
I just changed the oil. I'm running 10w40. Did not make any difference in the running. This idling is very rough like a missfire.
Is that my old jeep?

If so I recommend a swift kick in the junk, thats what I always did.
Nope, I just sold that jeep last week. On to the next victim :tonka: j/k
Put some fuel injector cleaner in the gas. It should go away.
This was going to be my next suggestion. Tonka pulled the connectors to the #1 and #5 injectors last night and it didn't make a difference in the way it was running. Now I am stuck on weather I should replace the injectors, or try a fuel injection cleaning :confused:
how is the fuel pressure have you thought about a fuel filter
does a 98 XJ have an external fuel filter? :confused:
 

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hicktown
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yes 98s have the intertal junk i wanted to replace te fitter on mine but cant
 

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Are you sure each cylinder is getting spark?
 

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Silver Lake
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Discussion Starter · #15 ·
Alright, I tried something today and it helped a little bit. Before I could disconnect the wiring for the #1 and #5 injectors and it would run the same. I had a mechanic at work do a "fuel injection cleaning" and now it seems to run better, I would say about 65-70% better. I did the same test again and disconnected the #5 injector and now it makes a difference in the way it runs. My question is: obviously I have some injector(s) plugged, do I run fuel injection cleaner through it again (this is a bottle that the jeep runs primarly off of that connects directly to the fuel rail) or do I do a seafoam treatment where you flood the engine out so the valves and everything gets cleaned out? Also, is there such a thing as using too much when it comes to these types of cleaning agents?


Side note: I also blew my waterpump out on the way home :(
 

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hicktown
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have fun with the pump hahaha and i whould do a seaform tement if you can the bottle cleans them but it still itnt the best option
 

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web wheeling, hard.
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It may be possible that some junk in the fuel tank got lodged in the injector (if your filter let it pass).

Did your problem come out of no where or did it develop with time?

Search the forums for seafoam and see what you get in terms of application.

I have had bad gas and vapor lock cause issues with idle, but they did not last long, it was more of a one time thing than an ongoing problem.

Was your jeep overheating at the time your idle was funny??? (water pump issue you mentioned may contribute)
 

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Silver Lake
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Discussion Starter · #18 ·
It may be possible that some junk in the fuel tank got lodged in the injector (if your filter let it pass).

Did your problem come out of no where or did it develop with time?

Search the forums for seafoam and see what you get in terms of application.

I have had bad gas and vapor lock cause issues with idle, but they did not last long, it was more of a one time thing than an ongoing problem.

Was your jeep overheating at the time your idle was funny??? (water pump issue you mentioned may contribute)
I'm kind of thinking along the same lines as you. It has run poor since I bought it and had been running bad for a while (cat. was plugged and it was in bad need of a tune-up, plug gap was at .082 instead of .035). I think with those 2 things wrong it caused it to carbon up really bad and now chunks are breaking off and getting stuck in the injector screens. I took the throttle body off the other night and cleaned it up good. There was a lot of carbon built up in the tps port.

Tonight I am going to replace the waterpump and try the seafoam. I don't think it'll hurt to try the $5 bottle fix (seafoam) :tonka:
 

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web wheeling, hard.
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water pump and seafoam, then re-evaluate. Good idea. Sounds like fuel delivery issues will be in the picture afterward though.
 

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Silver Lake
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Discussion Starter · #20 ·
water pump and seafoam, then re-evaluate. Good idea. Sounds like fuel delivery issues will be in the picture afterward though.
Do you mean as in a fuel pump problem or the injectors going out? :confused:
 
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