1992 ranger 2.3 hard starting and idling issues

[mattmattf14]

Hey everyone! I'm having issues with a 1992 ranger 2.3. The first problem I was having was when I would go out and start the truck I would have to crank the truck over multiple times before it would fire up and when it did it was starting rough. I just replaced the plugs and wires and now it won't start unless my foot is on the pedal and I keep the rpms up to keep it running. Eventually once it is warm enough it will idle on its own. I have checked fuel pressure, about 40-45 psi koeo and about 35 koer. Also replaced the fuel filter, checked fpr, cleaned the throttle body, tested iac, ect, I think maf has been replaced recently, checked egr, checked fuses just to be sure. This truck is getting the better of me, hoping someone can give me some direction. Thank you!!!

 

[tomw]

How did you test the IAC? It should provide a fast cold idle when first started, and then step back as the coolant & engine warm up. It should compensate for A/C compressor load if you have it, and power steering load at idle speed, bumping the idle as you turn the steering wheel.
tom

 

[mattmattf14]

I checked resistance of the solenoid which originally was about 8 ohms. Took it off and used jumper wires to see if the valve moved which it did. Also checked for 12v and ground at the harness and it does have it. After that i looked at some other things. Then I came back to the IAC and it tested bad so I replaced it. The truck started up on the second try today, its slightly warmer out. Was trying to turn the wheel and it stalled out on me.

 

[mattmattf14]

Just back probed the IAC with the engine running. I'm getting 10v on the ground so it looks like high resistance on the ground somewhere.

 

[mattmattf14]

Just checked resistance of ground circuit from iac connector to module connector and 0 ohms.

 

[mattmattf14]

Going to need some help now

 

[tomw]

The IAC does not get a straight 12V. It is a 'pulsed stepper motor' from what I understand, being provided with pulsed power so it would likely 'buzz' open to a given spot based on how long the pulses last.
You can measure across the terminals and expect low ohms as it is a solenoid rather than a 'motor' with brushes, armature, etc. I would not probe into the terminals when it is running, as I do not know what 'load' the computer can handle.
If you have not done so, remove the IAC and clean it. Dry it out with compressed air, and re-install. If it does not give a 'cold fast idle' when the engine is started from cold, or does not respond to A/C compressor load when the A/C is turned on, I'd replace it.
tom