Is my Engine Coolant Temperature Sensor showing me all the symptoms or the TPS causing hard acceleration or hard starting of the engiine?

2 Answers

  • paul h
    Lv 7
    3 years ago
    Favorite Answer

    Possibly...the PCM reads voltage data from the temp sensor (ECT or CTS) to know how hot or cold the engine is in order to determine proper injector pulses/fuel trims. A cold engine needs a slightly richer fuel mixture than a warm engine. So if the coolant temp sensor is sending faulty data showing the computer that the engine is warm when it's actually cold, the computer may adjust fuel mixtures too lean and can cause hard starting or power loss, etc.. The temp sensor location in the cooling system may also have an air pocket near it which can cause it to send faulty signals...not reading actual coolant temps.

    Bleed any air from the cooling system if it was low on coolant due to leaks or after any cooling system any leaks. Test voltage outputs from the sensor and check with tables from a service manual...or use a scan tool to read real time data from the sensor. Or just replace the sensor if that is suspect....check for any wiring defects, corrosion or loose connector in the circuit.

    Test the TPS and see if voltage readings are within specs...usually around 0.4-0.5 volts at closed throttle and should have smooth changes in voltages as you open the throttle from close to WOT. Any erratic readings or jumps in voltages show the TPS is bad...they can develop wear spots in some areas of the potentiometer and lead to faulty readings. A faulty or dirty IAC can also cause hard starting or low idle speeds but does not affect driving only operates at closed throttle.

    • Mark3 years agoReport

      I believe the information on the ECT SENSOR, that could be the cause of hard starting of my truck. I have now changed the TPS and before I had the IAC changed also. I am still getting hard starting in a parking lot or leaving a parking lot. I am going to have the ECT sensor checked before replace.

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  • 3 years ago

    You need a mechanic's $2000 scan tool to read the voltages on all your sensors.

    Source(s): Mitsubishi Master Tech
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