Mitsubishi Repair: 98 Ecilpes GS non running when warm., coolant temperature sensor, engine coolant temperature sensor

Question
Hi, I have a 98 eclipes with  a  Man. trans  non turbo with a 2.0.. I put a used motor in it last weekend and it runs great when cold.. just before normal temp. it mis fires and dies.Will not restart intill cold.(no spark and not pulse voltage to the injectors) it also make a lound sucking noise from the air intake box..
Thanks Bill

Answer
Bill,
This is most likely being caused somewhere in your air intake or air regulation systems.  Check your air box closely to be sure there are not air leaks, weak clamp seals, or splits in your intake tubes.  

Also check your Idle Air Control (IAC) motor. That is a little stepper motor attached to your throttle body that regulates your air flow when your car is idling.  Upon a cold start, your car's computer checks the engine temperature, and if it's below a certain value, it opens the IAC all the way to allow a lot of air to enter and warm the car up quicker.  As the temperature rises, the IAC lowers the amount of air that is bypassing the throttle plate and keeps your car idling around 800 rpm.  Inspect the IAC to be sure it's functioning properly.

Along that thought, the car's computer reads the engine temperature via the engine coolant temperature sensor.  If that sensor is malfunctioning, then it'll send false readings to your car's computer, and the computer may wrongfully tell the IAC to close completely.  Also along those lines, check your car's computer.  If the computer is not functioning properly, you'll have all sorts of starting and idling problems.  Be sure that all your wiring harnesses from the used engine you put into your car are all securely attached and making good contact.  Also be sure that computer in your car will work properly with the engine you dropped in it.
Good luck!