Idle Speed...

[Redneck Youth]

With the 4.0 ohv is there any way to turn the idle speed down, or is it all computerized. ive got a thrush welded muffler and it sounds really good at about 700-750, and it currently idles at approximately 1000... if there is any way at all to turn the idle speed down, please let me know... thanks...

 

[trail B2]

The computer decides the idle but you can go over every thing to get it working ok.My 93 Ranger 4.0 idles about 800 if you try to take the computer out of it it will die sometimes.

 

[Redneck Youth]

i heard somewhere that if you open up the throttle theres a stop screw behind it... but thats just what ive heard, im not going to try anything until i know for a fact that its not going to mess up my truck...

 

[Redneck Youth]

and it idles fine right now, i just like the sound when you let the clutch out and start to move, when it drops down to about 700-750... sounds like it has a performance cam

 

[Cam10]

That screw you heard of, if it is there, can only do so much. the idle is all electronic. The only way to adjust the idle would be to go to an autoshop and get them to use the scanner to get inside your rangers computer to change the idle settings.

 

[LIMA BEAN]

The PCM idles the engine based on what sensors like IAT, MAF, ECT, TPS, HEGO tell it.

 

[Redneck Youth]

alright, well im going to look farther into the screw method, and make sure it wont wreck anything, then ill try it, see how low i can get it, and if im not happy with that, ill take it in to get changed. thanks guys.

 

[Redneck Youth]

the guy im talking to also said he disconnected his IAC... and im wondering what that does

 

[Redneck Youth]

im guessing that means idle air control, and im wondering what the throttle stop screw will do without the IAC connected, im told that the screw act as an air control...

 

[LIMA BEAN]

The IAT gives the PCM air/fuel mixture temp info. The PCM in turn uses that info to control fuel flow, ign. timing and EGR.

 

[Redneck Youth]

if so, how did this guy do what he did? or did he just forget to mention something he did?

 

[Teddyzee]

There should be a set screw on the throttle body.
Simple turn it to lower the idle.

The typical way of doing it is unplug the idle air control motor, then set the idle at about 600 rpm, or the lowest it will idle on it's own. Then disconnect the battery for a couple minutes, plug the IAC back in, then reconnect the battery. Ideally you want to check the voltage (key on) at the Throttle Position Sensor after you've set the idle, should be in the neighbourhood of 1v.

http://sbftech.com/index.php/topic,1031.0.html

Some people are very afraid of adjusting the idle.

On both my 5.0 ranger, and 4.6 Mustang, I made a new gasket for the IAC with no holes, to block off the function. The high idle drives me nuts. It's designed to stay high until a certain vehicle speed (5mph?) for driveability.

 

[LIMA BEAN]

There should be a set screw on the throttle body.
Simple turn it to lower the idle.

The typical way of doing it is unplug the idle air control motor, then set the idle at about 600 rpm, or the lowest it will idle on it's own. Then disconnect the battery for a couple minutes, plug the IAC back in, then reconnect the battery. Ideally you want to check the voltage (key on) at the Throttle Position Sensor after you've set the idle, should be in the neighbourhood of 1v.

http://sbftech.com/index.php/topic,1031.0.html

Some people are very afraid of adjusting the idle.

On both my 5.0 ranger, and 4.6 Mustang, I made a new gasket for the IAC with no holes, to block off the function. The high idle drives me nuts. It's designed to stay high until a certain vehicle speed (5mph?) for driveability.

I see and know that but it the PCM is trying to give you the best of all worlds as far as AFR vs power and mandaded laws. They can all be ruled with resitence wires and zener diods or just flat out old schooling the engine right?

 

[Redneck Youth]

Mr. "Teddyzee" is the screw on the outside of the throttle body or inside it?

 

[Teddyzee]

I see and know that but it the PCM is trying to give you the best of all worlds as far as AFR vs power and mandaded laws. They can all be ruled with resitence wires and zener diods or just flat out old schooling the engine right?

It's just the idle speed, you may be over-thinking it!

Mr. "Teddyzee" is the screw on the outside of the throttle body or inside it?

Go under the hood of your truck, find the throttle body. On the side, top, or underneath, depending on the model, you will see the throttle cable. Find the direction needed and push the tb to rev the engine. When the cable comes to a rest again, you will notice it hits a stop, which will have a/the set screw. So it's on the outside. The screw may face up/down on a 4.0