Starts good when engin is cold, but not when engin is how

Here's some FYI on your situation. When you turn the switch on, all sensors are activated. One sensor is the cold start switch/temperature sending unit. When working properly, the sensor will send a pulse to the computer telling it to put the engine into cold start mode. Once this is done, a bit more fuel is added to the normal amount to the cylinders and the throttle is advanced slightly making the engine idle a bit faster for the extra fuel coming in. The engine is running to warm-up and the sensor then tells the computer to set the engine back to normal run mode. Once the engine is warm, the sensor is not being used for cold start mode. It will start right up and run smoothly. Now, since your truck is hard to start when cold, first thing you should check is the temperature sending unit wire connection first. if that connection is good, replace the temperature sending unit/sensor, and you'll be good to go. That's a simple repair that must be done when it gets hard to start when cold.

Try replacing the water temperature sensors. Sometimes there are 2 with one working the dash and the other working the engine. You are probably running too lean. The "cold start sequence" kicks in at a cold to warm temperature. If the sensor is stuck on hot it will be too lean to start.

You might try a new thermostat that may be more responsive than your old one. Check air filter for condition.

89 has the old stand alone spark distributor.
the ECU is spark free, (no player here)
so here is the list for this engine 1.3 or 1.6L
the 1.3 has a carb. (last one) and is NOT EFI ,
you never said which engine it has. so ill guess at the 1.6L
This engine will have hard starting for the fooling reasons.
we dont guess at it we just do the tests.

• Bad fuel.
• Never tunedup this decade or every 60,000 miles per opr. guide.
• low engine compression 150 good, if all are very low the cam timing belt slipped., (they all do , ignored) and is 60k service point.
• CEL dead key on, bad ECU or lamp bad.
• CEL glowing running, its telling you what is wrong, get the flash codes (DTC's)
• Too high fuel pressure. (bad regulator in front of TB)
• ECT bad. the 2 pin engine coolant temp sensor is bad. test it.
• The injector leaks in the throttle body (look with eyes)
• You find that adding 5-10% throttle cranking makes it more easy that is a bad, IAC valve, the valve at the base of the throttle body is stuck closed and kills all cold start air supply. making cold starts very hard, unless tricked with right foot. yes?
• when any gas engine fails to start cold, i check for too much or too little starting fuel. and for very good spark.
• Good engine, good spark the good fueling, there are tests for each, ASK?

It is a separate injector on a timer switch that is used for starting a cold engine. A cold engine needs more gas for good driveability.
I think it would be located on the intake manifold, but not positive on your Hyundai.

faulty engine coolant temperature sensor cause no cold start problems.but make sure engine has good spark plugs and wires.clean fuel injectors and new fuel filter.during cold start up or morning start up engine need rich fuel mixture good spark to start.

i use over haul carburetors.if idle speed screw too low engine wont start.if engine cold automatic choke need to be closed slowly open as engine warm up.if engine cold automatic choke need adjusting or fixed or if choke remain closed when engine hot vechicle will not start most time automatic thermostatic spring goes bad causing choke problems.

CHECK FOR SPARK AND FUEL.IF ALL IS GOOD A BAD COLD START VALVE WILL CAUSE COLD ENGINE START UP PROBLEMS COLD START VALVE DOES SAME JOB AS ENGINE COOLANT TEMPERATURE SENSOR IT ENRICHEN FUEL SYSTEM FOR COLD START UPS. DO LITTLE TUNE UP MAKE SURE SPARK PLUGS AND WIRES GOOD, REPLACE DISTRIBUTOR CAP AND ROTOR,CHECK IGNITION TIMING, REPLACE AIR FILTER AND FUEL FILTER. IF CAR GETTING FUEL AND SPARK.CAR TIMING BELT COULD HAVE JUMP TIMING IF TIMING BELT NEVER BEEN SERVICED OR REPLACED.

Sounds like the automatic choke is sticking.

It is not starting when cold since the cold start valve is not functioning. 1-It could be a coolant temperature sensor gives a wrong resistance readings when it cold so ECM doesn't know to send a signal to turn on the cold start valve. 2- It could be a bad cold start valve. I doesn't open even the ECM send a signal to it to open. You can see that Ohm reading on the terminals of the cold start valve is good, but it is still bad since your measuring the coil to open a valve showing the coil is good but valve gets stuck could not be opened. Good luck in checking these out for a good replacement..

Sounds like your cold start valve has an issue go to www.benzworld.org or peachparts.com for some good info on it.