We have a 1984 2M4. I found corroded wires on the sender near the t-stat. One located between stat and rear of the car. I grabbed one out of my parts bin that had the same threads and 2 leads thinking it would fix the code 14. I have tried wiring it up both ways but still have a check engine light and the car still runs like crap. Idols between 2000 and 2500 searching. The old sensor had a funny plastic contraption/connector and that is where the wires were corroded.
Looks like it is the coolant temperature sensor according to the Fiero store diagram.
Tia,

G

[This message has been edited by gjohnson (edited 08-26-2009).]

Yep. Code 14 is for the coolant temperature sensor for the ECM. It trips when the ECM senses a coolant temperature above 275*F for more than four seconds. The ECM uses the coolant temp signal to control fuel delivery, ignition timing, idle air, and TCC, so if you've got the wrong sensor, your engine won't run very well at all.

Must have grabbed a bad one then. I pulled it out of my Fiero parts bin from when we stripped out our doner 86 Fiero. Maybe I used a gauge sender instead of an ecm sender. 84's must have their own unique sender. Hmm. I will have to check when I have a chance. Thanks.