n14 fan almost always on

Check the fan clutch,switch, cylanoid, and air/electric lines

 

Check the A/C Module try to replace it and plug other one in if not connect to insite and check what the high side pressure sensor is reading maybe shorted and demanding fan if not check also with insite what intake temp and coolant temp are saying

 

just throwing it out there, are you overheating? maybe the rad is plugged?

 

Your high side a/c switch is most likely bad. A typical symptom is fan on almost immediately after engine is started.

 

I've encountered on two occasions with the N14 ecm's, both had high engine hours, the transistors for the injectors have high resistance and tend to give you issues with injector performance, i would double check that your getting 12v at the ecm power supply pins and ignition with the ecm disconnected, use a sealed beam headlight and see if she lights up, if it does then check the resistance of each injector circuits at the ecm connector. if it all checks out ok, then your ecm isn't providing the signal your injectors need to trim properly. I've replaced two sets of injectors on the same truck, checked fuel pressure, pressure was low cause i had play in the pump drive gear splines, replaced the pump, customer came back cause it was lacking power, so checked fuel inlet restriction, within spec. so i did the accelerated cylinder performance test, and all six seemed weak, so i changed the injectors to reman aftermarket(customer supplied), he then came back, and sent out the aftertmarket injectors, 4 of 6 failed bench testing, convinced the customer to have 6 OE injectors installed. so then once installed, and it still ran like it had a miss, underload especially i checked the ecm power supply, it was good, so i sent out the ecm to get checked and repaired, and it fixed the whole problem, the shop i sent it to informed me that the injector driver(transistors) fail and have high resistance and they don't pulse enough voltage to the injectors. if anyone can tell me if i'm wrong, i would appreciate greatly to be informed about it.

 

did you try plugging i another apads module for the ac