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Discussion Starter · #1 ·
When my cold start my Jeep it idles high until I hop in and hit the gas. That seems normal to me. It seems latley when at a light not in gear and not on the clutch I'm idling at 1500 rpms if I pump the gas a little it does down to 1000 rpms. I feel like it should be at 500. Am I wrong? 1990 4.2 5speed
 

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Mine settles around 600-900 depending on the weather. On hot days when I crank the pistons over it will churn up a hefty 1000-1400 Revolutions then settle back down. On cold days it will turn over and settle at the bottom end of the 600-900 spectrum. Manifold pressure and computers=awesome.
 

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my 93 2.5 idles high when it is cold started. shoots up to 1200 or so and settles at about 900. after it warms for 10 min or so it idles between 500 - 600 (i would say) just like it settles during the warmer months... As to why they idle different and why you can drop it by hitting the gas real quick though, idk...
 

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When my cold start my Jeep it idles high until I hop in and hit the gas. That seems normal to me. It seems latley when at a light not in gear and not on the clutch I'm idling at 1500 rpms if I pump the gas a little it does down to 1000 rpms. I feel like it should be at 500. Am I wrong? 1990 4.2 5speed
With my 89 4.2 5spd. it likes to idle at 800 rpm's. None of the carbs. like to idle at 500, too low. I would clean all of the linkage real good with choke and carb. cleaner. Your auto choke linkage might be hanging up a little. If you want to idle a bit lower, at about 800-900 rpm on a hot engine, just turn down your idle set screw about 1/4 - 1/2 turn. I wouldn't set it lower than that on a 4.2. Only adjust it when the engine is hot and idling in neutral. Check your auto choke setting. These carbs. like to be set at 1 notch rich. If you like where your cold idle set is, leave it alone. On my carb., cold, in extreme cold the high idle is 2,200. 1,800 if above 30 deg. Next kick down is 1,500. Warm engine is 800.
 

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Discussion Starter · #6 ·
I don't know anything about adjusting my Carb but one this I do know is its running rich. The tailpipe is blacker then the coal I will be getting for Christmas and I can smell it. I am also not familiar with the auto choke.
 

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It might be running rich. Get a can of carb. cleaner and spray everything in and out and with the engine running, including the linkage. That might help and is easy to do. If not you'll need a shop to adjust it for you. The auto choke housing is located on the left side of the carb. as you are looking at it from the front. You'll see a black housing with three screws. On the housing you'll see index marks with lean and rich on it. Check to see where the notch is aligned. To adjust it all you will have to do is loosen the screws, don't remove them, and slightly turn the housing to where the notch indicates one line to the rich side. Re-tighten the screws and you're done. If you would rather not touch it have a shop set it up for you. Cleaning the carb. in and out might save you a trip. I don't think the springs are causing the problem. Don't forget there should be a solenoid at the front right side of the carb. that is there to keep you from stalling out on a hard stop and it will bump up the idle if you have a/c. That can be adjusted also.
 

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Discussion Starter · #9 ·
I took it by the shop today and he said he could hear a vacuum leak. I noticed it once he pointed it out. Going to drop it off tomorrow night.
 
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