Rough Idle after warming up
#1
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Rough Idle after warming up
I have a '99 Cherokee Sport, 4.0L, with 111, 000 miles, Airaid intake and flowmaster Series 40 muffler. Other than that, everything else is stock. I have replaced the cps, the distributor cap, spray cleaned the iac without remvoing it from the throttle body and yet am still having a rough idle (tach will bounce around the 700 rpms range at idle) when the vehicle has reached operating temperature 195-210.
Was wondering if anyone had any ideas at what may be causing the rough idle now. I have taken it to one mechanic and he recommended a valve job. Was hoping there may be another cause.
Oh, also have run Seafoam, Chevron Techron, Lucas's High Octane boost, and a couple of Gum Out products through the tank and have had a mechanic do an injector cleaner through the fuel rail.
All suggestions and ideas would be appreciated.
Was wondering if anyone had any ideas at what may be causing the rough idle now. I have taken it to one mechanic and he recommended a valve job. Was hoping there may be another cause.
Oh, also have run Seafoam, Chevron Techron, Lucas's High Octane boost, and a couple of Gum Out products through the tank and have had a mechanic do an injector cleaner through the fuel rail.
All suggestions and ideas would be appreciated.
#2
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Year: 1999
Model: Cherokee
Engine: 4.0
Removing the iac is the only way to properly cleaning it. I would start there. Check for vaccum leaks around the intake manifold and check vaccum lines and connectors. Do the valves sound especially loud?
#3
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No. When the mechanic suggested a valve job, he stated that it was the exhaust valves of cyclinder 1 + 2 that had build up. That the engine had not been rev'ed high enough during the accumulation of the miles and the cylinders would fail to get hot enough.
I dont hear any out of the ordinary once it warms up. The exhaust sounds like it cuts out/back fires/ pudder (however you want to term it) when it warms up.
I dont hear any out of the ordinary once it warms up. The exhaust sounds like it cuts out/back fires/ pudder (however you want to term it) when it warms up.
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I notice that when I add Lucas Oil octane booster with 93 oct. gas, I have less of a rough idle problem. I took the iac out this weekend and clean both it and the hole it goes into. The cleaning helped a bit, but still is a bit rough when idling after it has reached temps.
I would figure if it is an exhaust valve going bad in 1 or 2 cylinder, wouldn't I notice it on acceleration as well a when it idles?
I would figure if it is an exhaust valve going bad in 1 or 2 cylinder, wouldn't I notice it on acceleration as well a when it idles?
#6
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Year: 1996
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hth
#7
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Year: 1999
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I wrapped my entire fuel rail, and all 6 injectors with heat tape (AZone $16). It did make a difference. Seafoaming, dumping the whole can in every fill up for the last 3 fillups, and it is calimg my idle down a lot. I read the 99+ has a carbon buildup issue and the valves stop rotating.
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My 01 has a similar issue. It idles at the half way point between 0 and 1000 so I am guessing that its idleing at 500 rpms. It bounces just below the 500 and I can watch the needle wiggle. Feels a little rough like its just barely stumbling. No missfires, no backfires just very quiet yet slightly rough. I have 144k on the speedo so I believe a rough idle is to be expected. I do plan on wraping the fuel rail and injectors but I believe mine could be resolved with new injectors all together. I can't really afford them right now so I will just deal with it until it gets really bad. I am thinking that my spark plugs are part of the problem also. I used the cheapest plugs when I changed them( the 1.19 champions). It had Autolites in it before. Otherwise, I'm just glad it starts every time every day.
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I wrapped my entire fuel rail, and all 6 injectors with heat tape (AZone $16). It did make a difference. Seafoaming, dumping the whole can in every fill up for the last 3 fillups, and it is calimg my idle down a lot. I read the 99+ has a carbon buildup issue and the valves stop rotating.
I may try to wrap those things in a heat tape. Thanks for the suggestion.
The mechanic that stated the Jeep would need a valve job stated that he tried to rotate the valves on cylinder 1 and 2 and that they wouldn't rotate, even after treating them with some thing (which was seafoam or an equivalent).
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Year: 1999
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My 01 has a similar issue. It idles at the half way point between 0 and 1000 so I am guessing that its idleing at 500 rpms. It bounces just below the 500 and I can watch the needle wiggle. Feels a little rough like its just barely stumbling. No missfires, no backfires just very quiet yet slightly rough. I have 144k on the speedo so I believe a rough idle is to be expected. I do plan on wraping the fuel rail and injectors but I believe mine could be resolved with new injectors all together. I can't really afford them right now so I will just deal with it until it gets really bad. I am thinking that my spark plugs are part of the problem also. I used the cheapest plugs when I changed them( the 1.19 champions). It had Autolites in it before. Otherwise, I'm just glad it starts every time every day.
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