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post #1 of (permalink) Old 09-16-2003, 11:50 AM Thread Starter
 
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rough idle after warm

After my jeep warms up to normal operating temp, and I let it idle for a about 3 min., the engine starts to miss-fire fairly bad, it gets worse the longer I idle. I've replaced almost every ignition part, and the carb. What else could make my rig run so poorly?
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post #2 of (permalink) Old 09-16-2003, 06:05 PM
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Re: rough idle after warm

just a guess but to me sounds like a vac. leak??
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post #3 of (permalink) Old 09-16-2003, 06:27 PM
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Re: rough idle after warm

are the spark plugs wet with oil??
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post #4 of (permalink) Old 09-17-2003, 10:17 AM Thread Starter
 
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Re: rough idle after warm

The spark plugs are new bosch splitfires, replaced a few days ago. As far as vacuum leaks go, I've checked every line, and sprayed some carb. cleaner on any questionable areas, no luck finding any leaks.

I just replaced the fuel pump a few weeks ago, could it be the old fuel filter restricting fuel from the carb?

Thanks,

Tim
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post #5 of (permalink) Old 09-17-2003, 12:52 PM
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Re: rough idle after warm

You have a German engine in it?
No? Then why do you use cheapie plugs that aren't made for that engine. They "cost" very little, but parts houses charge like they were real spark plugs.

Bosch uses the "one size fits all" theorey. They have very few numbers compared to a legitimate spark plug maker. Ask your wife how "one size fits all" works for her.
The heat range can be waaaaay off with them, and indexed wrong, causing your troubles. What fits a Yugo, VW, or Moskovich doesn't mean it'll work in a Jeep.

Else it still sounds like one cylinder's lean for some reason.
Try disconnecting plug wires one at a time - engine R's should drop the same for each cylinder. Find the low one, check for vacuum leak near it. Check to make sure the EGR valve is closing fully too. Disconnecting the vacuum line does not check it that way. You have to remove it and fill it with alcohol to see if it leaks. An EGR leak (if equipped) acts like a vacuum leak but adding fuel or carb cleaner won't help, as it's "dead air" - no oxygen.
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