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Unread 07-12-2010, 08:48 PM   #1
Sykora171
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How to adjust idle?

My 1994 Jeep Grand Cherokee Laredo is acting up. On cold start, my jeep's idle is just above the zero on the tachometer. so its about 100 rpms. after driving for a while it finally goes to about 400 rpms. which is still too low for my taste. whats going on? and how can this be adjusted??

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Unread 07-12-2010, 11:38 PM   #2
greyarea
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How is it running at those rpm?
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Unread 07-14-2010, 01:10 AM   #3
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Quote:
Originally Posted by greyarea View Post
How is it running at those rpm?

You got me man. lol you know how you can hear the pistons going when the engine is on? you can seriously hear how slow they're moving when its at 100 rpm. it doesnt even make sense. the jeep just doesn't wanna give up. i think i can i think i can!
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Unread 07-14-2010, 01:18 AM   #4
MilitaryJK4455
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Tighten down the cable thats attatched to the throttle thingy on top of the motor until the idle is where you want it... You could use your fingers on a 350... This could be totally wrong as I know nothing about your motor... Hope this helps


Its not directly on top of the motor btw... It should be off to one side.
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Unread 07-14-2010, 08:26 AM   #5
lostone73
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That engines idle speed is controlled by the PCM and I.A.C solenoid. There is no external adjustment. there is another problem causing your low idle. IE; vacuum leak, low fuel pressure ect.

Hope to be a help.
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Unread 07-14-2010, 11:24 AM   #6
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Quote:
Originally Posted by lostone73 View Post
That engines idle speed is controlled by the PCM and I.A.C solenoid. There is no external adjustment. there is another problem causing your low idle. IE; vacuum leak, low fuel pressure ect.

Hope to be a help.
thanks guys, i just remembered that the power cord thing (dont know the name) that plugs into the throttle position sensor was loose before and cause my idle to go craazy. i'll clean the IAC and make sure that thing is in all the way. i'll get back to you guys on that. but keep the thread going
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Unread 07-14-2010, 05:25 PM   #7
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OKay I need URGENT help now. throttle body is clean and stuff. but just now, the jeep lost all idle. had to restart it 50 times to get it home. it wont idle at all. unless i unplug a vacuum line at the end of the block. anyone know why? what does this mean?! help!
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Unread 07-14-2010, 10:57 PM   #8
greyarea
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Sounds like the idle circuit is cloged with carbon. Did you remove the throttle body from the intake to clean it?
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Unread 07-15-2010, 02:21 AM   #9
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Quote:
Originally Posted by greyarea View Post
Sounds like the idle circuit is cloged with carbon. Did you remove the throttle body from the intake to clean it?
ah no i didnt today..but i actually removed the IAC to clean it like a week ago. thats when i bumped my throttle position sensor (tps) and it broke. so we put the old one in cause we replaced it before. i think it might just be the tps..who knows. i ordered another one. should be here in a few days..this sucks. it seriously idles at maybe 50 rpm. that shouldnt even be possible!!
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Unread 07-15-2010, 01:41 PM   #10
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okay so i removed the IAC and cleaned it throughly. and i thought hey, i know i have a new IAC in the garage that we never used. so for the heck of it i put it in and now my idle is in around 500 rpm. still a little lower than average, but it'll do. haha at least its running again. and for the heck of it i thought ill run the engine without an IAC to see what happens. big mistake. hahahahaha went from 0 to 3000 rpms in half a second. but yeah, idle is kinda normal now.
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Unread 07-15-2010, 05:54 PM   #11
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Sorry I did not clarify properly I was referring to the air passage in the throttle body not the IAC. I had mine on a dodge clog on me and had similar symptoms as you do now with the new IAC and pulled the TB and cleaned the passage with a dental pick to get the carbon buildup out and it ran great.
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