The fast idle solonoid on my 88 3.9L works good, but it never disengages, it keeps the rpms around 950-1000 all the time, if I crank in the set screw on the tip, it compensates right after I start it and it stays around 1000 rpm. What is keeping it engaged? Is there a sensor doing this, computer issue? No check engine light or codes. Really burns thru the gas running his rpm all the darn time. Looking for items to look at as I cant find our chiltons manual for the dakota I saved from when we used to have one years ago. Thanks Mike and Michele T

 

I'm not to familiar with the Throttle body injection systems. But I would think there might be a vacuum leak or the ignition timing is off.

 

Hows the temperature sensor for the coolant and how is the thermostat

 

I don't know if yours is the same, but on my 91, the procedures to adjust the Idle Speed Control (ISC) Actuator are as follows:

1. Start vehicle and allow to run for two minutes.
2. Shut vehicle off. Allow 60 seconds for the actuator shaft to fully extend.
3. Disconnect the wiring connector to the idle speed control actuator.
4. Disconnect the wiring connector to the coolant temperature sensor.
5. Hook up a tachometer to the engine.
6. Start the vehicle.
7. Adjust the extension screw on the actuator shaft until the rpm is within the
specifications below.
-If vehicle mileage is less than 1000 miles, set to 2400-2500 rpm.
-If vehicle mileage is greater than 1000 miles, set to 2500-2600 rpm.
8. Shut off vehicle.
9. Reconnect the ISC actuator motor electrical connector.
10. Reconnect the coolant temperature sensor.

 

I got it to idle down, idle controler was stuck, took it appart, cleaned and greased it. Now she idles down once warmed up a bit. Thanks guys. Mike