Motor wants to die for the first few minutes.

[DamnYankee]

When I first start my motor it i have to keep my foot on the throttle to keep the rpms up or it will die. After a few minutes, it’s fine. What would cause that?

 

[RonD]

First I would test IAC(idle air control) Valve
After engine is warmed up, let it idle and unplug the 2 wire connector on IAC Valve
Idle should drop down to 500RPM or engine may even stall, either is good it means IAC Valve(and computer) was working to set warm engine idle, usually about 650rpm with manual transmission, 750 with automatic

If idle doesn't change then IAC Valve may be stuck, it can be cleaned and tested
Read here: https://www.explorerforum.com/forums/index.php?threads/iac-valve-cleaning-thread-w-pics.84220/

When IAC Valve is off the intake, turn on the key, plug 2 wire connector back in, valve should move(open) about 3/8" inch, then unplug the 2 wire connector and it should close, repeat as you see fit to determine its working as it should.



If idle does drop then I would replace ECT(engine coolant temp) sensor, not an expensive part, so often just easier to replace than to test it
Fuel injected engines have TWO coolant temp devices
1. ECT sensor, always 2 wires, 5volt, only used by the computer to set Choke and cold/warm idle
2. ECT sender, usually 1 wire, 12volt, only used by dash temp gauge

If the ECT sensor is "telling" the computer the engine is already warmed up, then computer doesn't set Choke or higher idle, computer just thinks its a "restart" after running into the store or stopping for gas, so cold engine struggles to run on warm engine fuel mix

 

[DamnYankee]

First I would test IAC(idle air control) Valve
After engine is warmed up, let it idle and unplug the 2 wire connector on IAC Valve
Idle should drop down to 500RPM or engine may even stall, either is good it means IAC Valve(and computer) was working to set warm engine idle, usually about 650rpm with manual transmission, 750 with automatic

If idle doesn't change then IAC Valve may be stuck, it can be cleaned and tested
Read here: https://www.explorerforum.com/forums/index.php?threads/iac-valve-cleaning-thread-w-pics.84220/

When IAC Valve is off the intake, turn on the key, plug 2 wire connector back in, valve should move(open) about 3/8" inch, then unplug the 2 wire connector and it should close, repeat as you see fit to determine its working as it should.



If idle does drop then I would replace ECT(engine coolant temp) sensor, not an expensive part, so often just easier to replace than to test it
Fuel injected engines have TWO coolant temp devices
1. ECT sensor, always 2 wires, 5volt, only used by the computer to set Choke and cold/warm idle
2. ECT sender, usually 1 wire, 12volt, only used by dash temp gauge

If the ECT sensor is "telling" the computer the engine is already warmed up, then computer doesn't set Choke or higher idle, computer just thinks its a "restart" after running into the store or stopping for gas, so cold engine struggles to run on warm engine fuel mix

Forgive my ignorance but can you tell me where to locate these two parts so I can check them?

 

[cbxer55]

The IAC is the cylindrical looking part on the side of the throttle body. Has one electrical connector attached to it. Simply unplug the connector, the engine should either idle very low, almost stall, or stall. As was said above, it's normal. My 98 Ranger, has been an IAC eater. Lost count of how many I've had to take back to Auto Zone because they kept failing. I finally opted to pay the additional money and get their Hitachi IAC, like back in 2015. Haven't had another problem with it since. Their cheap $39.95 part is made in Mexico. Their premium part is made in Japan Hitachi and costs twice as much. The cheap one's have a one year warranty and rarely make that one year. The Hitachi has a five year warranty, and mine's four years old now.

Picture below, the shiny intake tube. On the right, you see the blue sleeve. Right above that is the IAC. Cylindrical looking contraption with a plug on the end. Maybe the 2.9 is different than the 3.0???

 

[DamnYankee]

Ok. The IAC is fine. On to the ECT. Is it the two wire sensor just above and behind the thermostat housing?

 

[RonD]

Yes, its the TWO wire sensor near the thermostat housing, 1 wire sender is near-by but the 2 wire is the one the computer uses

 

[DamnYankee]

Thanks!