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Unread 06-28-2010, 03:44 PM   #16
tomvid
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Thanks Wheelin...
3.9 Was the highest I ever got on it. 3.71 was typical, Should this change my concerns? When should I start to be concerned?

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Unread 06-28-2010, 03:50 PM   #17
Wheelin98TJ
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Between 3.5 and 4 volts is normal.
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Unread 06-28-2010, 04:00 PM   #18
RCFrank
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How about the Idle Air Control being stuck open? It could either be mechanical or the motor is getting a signal to open.

I can't find much in the shop manual as to what the electrical measurements should be at the motor. It just says the computer uses it to set the idle.
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Unread 06-29-2010, 08:31 AM   #19
tomvid
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Yeah, I cleaned that up nice and good. And it was replaced about two years ago. I dont know... This one is really stumping me...
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Unread 06-29-2010, 09:10 AM   #20
RCFrank
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Quote:
Originally Posted by tomvid View Post
Yeah, I cleaned that up nice and good. And it was replaced about two years ago. I dont know... This one is really stumping me...
It would seem like idling at 2200 would take quite a bit of air. I had a broken vacuum line from the manifold to the HVAC control and the computer still kept the idle normal. It even passed Calif smog. Have you tried the trick of spraying water around the engine compartment to see if it affects the idle speed. That would let you know whether the problem was an internal or external source of air.

If it's not a simple external leak about the only thing left is the idle air or main throttle. The idle air is controlled by the computer so if the motor is OK then the computer may be giving it bogus info. In that case either the computer is kaput *hope not* or one of the inputs the computer uses has a problem. My old CJ engine was so simple!
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Unread 06-29-2010, 09:18 AM   #21
tomvid
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Yeah, I sprayed all over the place... I checked for leaking vacuum leaks at the lines.... I couldnt find a vacuum leak anywhere... I think I may have to bite the bullet and take it in somewhere... AS much as I HATE to do that!!!!
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Unread 06-29-2010, 11:00 AM   #22
RCFrank
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Quote:
Originally Posted by tomvid View Post
Yeah, I sprayed all over the place... I checked for leaking vacuum leaks at the lines.... I couldnt find a vacuum leak anywhere... I think I may have to bite the bullet and take it in somewhere... AS much as I HATE to do that!!!!
Sounds like you have been pretty thorough. I've never messed with the idle air motor and it's not well described in the shop manual. Is there any way to see its position or movement with the engine running? Or how about somehow blocking the idle air passage? If it still idles with the passage blocked it would say the source of idle air is coming from somewhere else.

Also, is the main throttle closed against the adjustment screw?

Some of this is pretty obvious, but with a problem like this I don't assume anything. I'm an electronic engineer and do a lot of troubleshooting. I can't count the number of times I have kicked myself in the butt for missing something obvious.

When you figure it out I'd like to know what it was. I would like to be able to control the idle speed via the idle air motor. Just a couple of weeks ago it would have been great if I could have set the idle up to 1500rpm or so for climbing over some rocks on a narrow ledge road with a pretty good camber. (mine is a stick). Most of the time I did OK just idling over them at 800, but in a few cases it couldn't quite handle it. The cheap hand throttles are too clunky for finessing a tight spot.
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Unread 06-29-2010, 11:43 AM   #23
tomvid
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Yeah Frank, you bring up a good point. When I Stop the flow of air out of one of the incoming streams to the IAC from the throttle body it does drop the RPM'S to about 1200. Now that is only one of the incoming streams, there is on above and one below the butterfly in the throttle body. Your bring up a very good point but really anytime you choke the egine of air it will bring down the RPM's. I will DEFINITLEY let you know what happens in the end. Yes, Frank, it would be really useful when climbing... Thanks for all the responses....
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Unread 07-01-2010, 08:41 AM   #24
tomvid
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Well, it ended up being the Idle Air Control Valve.
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Unread 07-01-2010, 09:33 AM   #25
RCFrank
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Quote:
Originally Posted by tomvid View Post
Well, it ended up being the Idle Air Control Valve.
Sometimes it is the simple things. Could have been a lot worse like the computer.

Anyway, thanks for the update. That gives me an idea on using the Idle Air Control as a sensitive hand throttle.
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Unread 07-01-2010, 09:48 AM   #26
tomvid
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I dont think that you can manually manipulate or set them. It said this specifically in the installation instructions...
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Unread 07-01-2010, 11:01 AM   #27
RCFrank
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I dont think that you can manually manipulate or set them. It said this specifically in the installation instructions...
Being an electronic type my idea is to insert my own control circuit between the valve and the computer. Since your bad one didn't set any codes and had run your idle up to over 2000 it might work.
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Unread 07-01-2010, 11:55 AM   #28
tomvid
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If you can get that to work, that would be really useful climbing... Thats for sure!!!
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Unread 10-17-2010, 10:06 AM   #29
twanger1994
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If this will give you a high idle. could it possible lower the idle as well? my 00 wrangler sport 6 cyl. idles from 550 to 475. it will stall occasionally. usually, if your at a red light just as you think about letting off brake to move, stall.... any ideas Thanx

Last edited by twanger1994; 10-17-2010 at 10:18 AM..
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Unread 10-17-2010, 10:44 PM   #30
bradb511
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I had the same prob but mine was running at 1500 rpms. Turns out i had several loose bolts on my headers.
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