1988 ranger 2.3 rough idle when warm hcs almost 2000

[rcp5000]

Truck runs good cold. Seems like when it warms up to operating temp it starts to idle rough. Also has extremely high emmission. Pulled code 14 24 55 replaced Distributor/ICM Tried a reman cardon eec truck wouldnt run only on carb and choke cleaner. I want to change air charge temp sensor but everybody trying to sell me the wrong one. I could really use some ideas.

 

[RonD]

ECT sensor would be most like sensor to cause the symptoms, IAT(intake air temp) doesn't change things enough to cause rough idle, slightly lower MPG and slightly higher emission would fit though.

ECT sensor is on the drivers side of the block, toward the front, below the intake, best seen from drivers side wheel well.
It is a two wire sensor, the computer uses this sensor to set open loop or choke mode, if this sensor shows engine is cold.
As ECT sensor warms up idle should drop and computer will lean out the fuel for best MPG.
If idle is high when first starting cold engine and then slowly drops to normal idle, 700-800rpm, when warm, ECT is working.

If idle isn't dropping then ECT sensor may not be changing enough, or at all, but that should cause check engine light to come on, code 21

IAT sensor is usually found on the Air Cleaner housing on earlier Rangers, two wire sensor.

The 55 code is low voltage at computer, never seen that one before, on my EEC-IV computer diagram pin 5 is not used, so not sure what that codes is all about

 

[rcp5000]

Engine coolant temperature I think its been replaced how can i test it

 

[RonD]

It is hard to get to, but test is easy.
You need a Volt meter, set it for DC
Ground the meter
There are 2 wires on the ECT, one will be 5volts, 4.5-5.0vDC.
The other wire is the one you want, it will be above 2volts with cold engine, as engine warms up it will slowly drop to below 1volt.

These rarely fail so if it is new I would make sure the wiring to it is good.

Not sure where the Computer is on an '88, passenger side kick panel would be my guess.

I would start there to test ECT voltages.
Diagram and pin numbers here: http://www.auto-diagnostics.info/ford_eec_iv

test pin 7 voltage as truck warms up
Also check pin 26 to make sure it is 5volts

You need to test with wires connected, I use sewing pins to pierce wires for testing, they don't make big holes.

 

[tomw]

I would check the fuel pressure & regulator as the mix is diddled richer when cold, and leaner once warmed up. You run well cold, but stumble a bit when warm. If the regulator doesn't work, you might not have enough pressure to operate properly. You can also check delivery volume over time to know the filter is not blocking fuel flow.
tom