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Adjust Idle speed

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Old 05-10-2007, 08:12 PM
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Adjust Idle speed

hey i have a 1989 Camaro Rs with a 305 and its TBI is it alright if i adjust the idle speed at around 1000 in parking and 800 or around there in drive well let me know if that will affect my car if i do that because my car runs better when it is accelerated thanks
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Old 05-10-2007, 08:16 PM
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Re: Adjust Idle speed

Welcome to the forum, although I am newer to cars so cant help you lol but would just like to say welcome! This place is great and will help with just about everything! =)
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Old 05-13-2007, 01:04 AM
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Re: Adjust Idle speed

There is an adj. screw in the trottle body that can raise the idle RPM. 1 or 2 hundred RPM adj. is ok. TPS is probably worn some. 1,000 at idle in nutral and 800 in gear will work but every time you start your engine, the initial and cold RPM will go crazy for a couple of minutes till the IAC valve closes and closed loop takes control .
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Old 01-20-2016, 05:56 PM
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Re: Adjust Idle speed

my idle runs a bit high. even after it warms up. But if I shut the engine off after it is warm, it idles fine. Til after I drive it a little. Then the idle is high again. Til I shut it off and restart it again. New iac
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Old 01-20-2016, 08:19 PM
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Re: Adjust Idle speed

This is something that anyone having idle trouble should do.


First the timing must be set to the stock setting =


(Start car and idle until the car is at operating temp. Disconnect the EST wire, adjust timing, reconnect EST wire. Shut off car) .



Now the "Setting minimum idle speed" procedure is done like this.
( the IACV will be set correctly when your done )


Jump the A to B terminal under the dash

Turn the key on but do not start it

You should hear a slight ticking coming from the IACV.

What 45 seconds then unplug the IACV with the ignition still on.


Disconnect the EST wire and remove the jumper.


Start the car.


It may be necessary to hold the throttle open slightly to prevent the engine from stalling.


Allow the engine to reach normal operating temperature.


Connect a tachometer. I used a digital timing gun with RPM feature.


Adjust the minimum idle speed using the throttle stop screw.


My Chilton’s says set it to 700rpm in park on an 89 TBI 5.0 auto.

When done shut the car off and reconnect the EST wire.

Plug the IACV back in.


Drive the car for 20 minutes or so that way the ECM can make adjustments to the new settings.


If that does not fix the problem at least you will know that the Timing , IACV and minimum idle speed is set correctly and can eliminate them as suspects.

Last edited by Ron U.S.M.C.; 01-20-2016 at 08:49 PM.
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Old 01-20-2016, 11:50 PM
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Re: Adjust Idle speed

Originally Posted by Ron U.S.M.C. View Post
This is something that anyone having idle trouble should do.


First the timing must be set to the stock setting =


(Start car and idle until the car is at operating temp. Disconnect the EST wire, adjust timing, reconnect EST wire. Shut off car) .



Now the "Setting minimum idle speed" procedure is done like this.
( the IACV will be set correctly when your done )


Jump the A to B terminal under the dash

Turn the key on but do not start it

You should hear a slight ticking coming from the IACV.

What 45 seconds then unplug the IACV with the ignition still on.


Disconnect the EST wire and remove the jumper.


Start the car.


It may be necessary to hold the throttle open slightly to prevent the engine from stalling.


Allow the engine to reach normal operating temperature.


Connect a tachometer. I used a digital timing gun with RPM feature.


Adjust the minimum idle speed using the throttle stop screw.


My Chiltonís says set it to 700rpm in park on an 89 TBI 5.0 auto.

When done shut the car off and reconnect the EST wire.

Plug the IACV back in.


Drive the car for 20 minutes or so that way the ECM can make adjustments to the new settings.


If that does not fix the problem at least you will know that the Timing , IACV and minimum idle speed is set correctly and can eliminate them as suspects.
What is the est wire?
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Old 01-21-2016, 04:35 AM
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Re: Adjust Idle speed

EST = Electronic Spark Timing,


It removes the ECM from the timing procedure.


You want "base" timing to be set "with out" the ECM's influence . Here's a photo of the connection to unhook as described earlier. Mine is next to the blower motor . It has a brown wire with a black stripe.


I also included a diagram of the ALDL Terminal just above your right leg under the counsel.
When you use a paperclip to jump be sure it does not have a very thin plastic coating on it. Its really hard to see but your jump will not work with it on.


Also here's a link to save for future reference. I just added it to my desktop with a short cut. Just scroll down on the page.= http://chevroletforum.com/forum/gene...cronyms-11094/







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Old 01-21-2016, 04:53 AM
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Re: Adjust Idle speed

you know the timing can be changed with the engine not running. ECM will stop adjustments while it is running
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Old 01-21-2016, 04:57 AM
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Re: Adjust Idle speed

Originally Posted by Biggd4355 View Post
What is the est wire?
I have already done this procedure. The iac stuck in the shut position. So I replaced the iac. Still idles up after running
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Old 01-21-2016, 01:56 PM
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Re: Adjust Idle speed

> The iac stuck in the shut position.

If by this you mean that the IAC steps are at zero, then there is a vacuum leak.

If there is a lower temperature thermostat in place that can cause a high idle. Stock is 195* F.

RBob.
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Old 01-21-2016, 05:10 PM
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Re: Adjust Idle speed

I used to run a 160, but upgraded to 180. 195 is the hottest you can get.
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Old 01-21-2016, 05:12 PM
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Car: 1989 Iroc-Z Camaro
Engine: TBI,5.0
Transmission: Automatic 700R4
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Re: Adjust Idle speed

Originally Posted by Biggd4355 View Post
you know the timing can be changed with the engine not running. ECM will stop adjustments while it is running

That's why it done with the EST disconnected.
And the car must be warmed up to operating temperature not to mention the distributor must be turned to ether advance or retard the base timing.


Then a "digital" timing light or equitant "must" be used to set the proper minimum idle speed.
I originally purchased a basic timing gun but it is pretty much "useless" compared to the new digital one I have now.


Link to the gun =
Amazon.com: INNOVA 3568 Digital Timing Light: Automotive Amazon.com: INNOVA 3568 Digital Timing Light: Automotive

Last edited by Ron U.S.M.C.; 01-21-2016 at 05:20 PM.
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