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Unread 04-14-2002, 10:49 PM   #1
Rudy
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Join Date: Nov 2001
Location: Vallejo
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unusualy high idle rpm

Some times when I start my 89 Cherokee 4.0 the engine will rev up to around 3000 rpm and wont come down unless I shut down the car and restart it. In some cases I have had to turn off the car and start it a couple of times to get the idle down. This also sometimes happens while the car is running, meaning The car starts just fine then I will notice while at a light or something that the idle is up to high, around 3000 rpm.
If any knows what is going on here or has experienced the same thing, a cure for this problem would be appreciated. Thanks

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5.9 litre, stock. 89 XJ with 5 inch lift, roof rack and 31X10.5`s on 589`s. 76 Wagoneer with 401,edelbrock,MSD,Header and B&M auto shifter.
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Unread 04-14-2002, 10:56 PM   #2
BlazinYellowTJ
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Join Date: Apr 2002
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my friend has an 87 with the same problem...idles high when first started, but comes down after he drives it for a while. i wonder if there is a connection? hmmm
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Unread 04-14-2002, 11:00 PM   #3
Rudy
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If you find out any more on this problem from your friend I sure would like to know how to fix it.
Thanks, now I dont feel so all alone.
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5.9 litre, stock. 89 XJ with 5 inch lift, roof rack and 31X10.5`s on 589`s. 76 Wagoneer with 401,edelbrock,MSD,Header and B&M auto shifter.
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Unread 04-14-2002, 11:31 PM   #4
Drunc
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are you sure the choke just isn't sticking??
make sure the petals and lnes aren't catching on anything
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Jeep: '88 YJ Laredo I6, Kenwood Deck, Amp and 6x9's, 10" pioneer sub, 2.5" Skyjacker Kit with a 1" body and new front shackles, 32" Mud Kings on 8" Desert Crawlers, CJ style replacement mirrors, ditched the trackbars and the endcaps
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Unread 04-15-2002, 12:52 AM   #5
Rudy
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Where would I find the choke on my fuel injected 4.0?
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5.9 litre, stock. 89 XJ with 5 inch lift, roof rack and 31X10.5`s on 589`s. 76 Wagoneer with 401,edelbrock,MSD,Header and B&M auto shifter.
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Unread 04-22-2002, 04:04 PM   #6
jg
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I have had the same problem with my 1990 4.0L Comanche. Changing the EGR valve reduced the problem alot, but it still happens occasionally, especially when I put low grade fuel into it - it really appreciates a tank of premium, although mid-grade works fine too.
It is most likely an issue connected with vacuum lines and/or emmission control components. Let us know what you come up with - this is a VERY common problem.
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Unread 04-23-2002, 02:12 AM   #7
MonsterJ20
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I had a motor with a bad tempature sensor that sent the idle up to over 3000 rpm. It took three different mechanics to figure out what was wrong. I can't promise it'll fix your problem but it fixed mine.
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Unread 04-23-2002, 12:47 PM   #8
Rudy
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Thanks for all the feed back, I`m going to try the temp sensor. I think the only way to change the egr valve is to replace the entire valve cover.
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5.9 litre, stock. 89 XJ with 5 inch lift, roof rack and 31X10.5`s on 589`s. 76 Wagoneer with 401,edelbrock,MSD,Header and B&M auto shifter.
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Unread 04-29-2002, 10:13 PM   #9
I-4
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i learned about this sensor bs the hard way.i wouldn't just go replacing sensors on someones advice.it get's rather expensive if it's not the fix.it sounds like a throttle position sensor...but don't take my word for it. spend the money and have a diagnostic done.it will save much heartache and money.btw, the 4 cylinder uses the same tps as the 4.0.it is a problem child.
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