WHAT THE F%&#!!!

OK, I have been having the high idle problem for months now, replacing nearly everything related to the TBI system. Thanx to everyone for their input, BTW!
Yesterday the idler pulley crapped out while I was hooking up my trailer and it overheated(temp gauge was pegged well over the 260 on the gauge). Nothing I could do to cool it off so I just shut it off. After a couple errands in our other vehicle, I went and got a new idler($17.40 or so), removed the old(plastic) and installed the new(stamped steel), the belt was good so I reused it(though routing was interesting with no diagram(third time was a charm)). Only lost about a quart and a half of coolant.
Started it up(same as before, needed the throttle cracked), let it run a bit, then drove it home...
NOW, THIS is where it gets interesting... Pulled up in front of my house and something was different...it was idling at 700RPM! Switched it to an AC setting and it went to about 850-900RPM! Went out this morning to start some running and it started first try with no throttle, went to 1000RPM then 1100RPM, then down to 700RPM after it warmed up! Started and shut off 4-5 times with no starting or idle problems(went to 8-900 and dropped right down to 700)!
WHAT THE F%&#????
Any ideas on this new tidbit, anyone? Everyone?
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Shades wrote:

High underhood temperature could have actually caused a poor electrical connection to move ever so slightly & make better contact. Maybe your touching something while replacing your pulley & belt caused a bad connection to become better.
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Good point! After some further errands this afternoon, it started acting up again(high idle), but not constantly.
Really getting puzzled now...I guess I needed more confusion in my life...
*sic*

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Greetings,
I agree with the possibility that it may be a bad connection(s) that was somehow aided by either the high temps or the work you did. I would suggest checking the connections to the Intake Air Temp sensor and Coolant Temp Sensor (as well as the sensors themselves). A fault in either one could lead the ECM to believe that the motor is much colder than it actually was which could cause it to run at a higher idle.
Cheers - Jonathan
"Shades" <shades_1970(at)netins(dot)net> wrote in message

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There is no Air Intake Temp Sensor.
CTS is new with new plug, as originally stated.

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On Wed, 25 Jan 2006 12:44:37 -0600, "Shades" <shades_1970(at)netins(dot)net> wrote:
Maybe the added pressure and heat scared the shit out of it and it behaved for a bit? *g*
Not having a clue about the cumputer/fuel stuff, I'll take a WAG and say that maybe sensing the overheating condition temporally kicked the TBI to change the mixture??

Mac https://home.comcast.net/~mac.davis/wood_stuff.htm
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"Shades" <shades_1970(at)netins(dot)net> wrote in message

-----
Snip.
I assume that you changed all the tbi gaskets, including the alum. ring spacer between the top of the tbi, and the bottom of the air cleaner?
Forgive me if this has already been brought up.
HDS
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Gaskets done.

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"Shades" <shades_1970(at)netins(dot)net> wrote in message

----------
Hmmmm... dam.
Take the IAC out (Idle Air Control, on the back of the TBI with a 4 wire connection), and gently wiggle the plunger as far back as it'll go. Take the truck out on the road, get her warmed up and stay over 30mph for about 5 miles. That will reset the IAC.
I figure it's pulling air in somewhere.. vac hose most likely. But it's possible you got another bad IAC if you already replaced it.
Real stumper for sure.
Check list:
Fuel press. Fuel press reg inside the TBI (Spring, gaskets, and "membrane") TBI gaskets. Vac hoses PCV Air pump check valves (if equipped) IAC
Gremlins (Hard to find/kill)
HDS
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Gone through 2 used IAC valves and one new. All doing the same thing. There is a wrong signal originating from somewhere that is telling the IAC valve to fully open. There is no black smoke at any time, so its not flooding in any way.
Like the follow up post I did(in this thread) said, after the overheating incident, now 75% of the time it is idling right at all temps(still not starting exactly right but acceptable, 1000-1200 at first start and 700RPM warmed up). Before the overheating, it was idling wrong 100% of the time(HARD starting, 600-800RPM first started and 1200RPM warmed up).

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On Wed, 25 Jan 2006 12:44:37 -0600, "Shades" <shades_1970(at)netins(dot)net> wrote:>OK, I have been having the high idle problem for months now, replacing

Idle Air Control Valve ?
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Mentioned and already cone.

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Shades, I agree that you could have an air leak. Check the throttle shaft in theTBI for slop. If the bushings or shaft are worn, you could get air leakage and/or the TPS could send out a false signal (I've only seen it twice but it does happen)

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The throttle shaft is as tight as any I have felt.

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"Shades" <shades_1970(at)netins(dot)net> wrote in message

I don't know if this applies to your situation, but I had a similar problem with a dodge 600 4 banger. It had similar problems. high idle, hard starting.
It had a bad head gasket, combustion gas leaking into the coolant, forcing coolant out of rad until the termostat opened.
After I repaced the head gasket, all the problems went away including the high idle!
Maybe the overheating caused the gasket to "seal up". Try checking the compression.
hope this helps!
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