Why does my carina 212 stutters in the morning when cold and runs fine when hot I change the coolant temperature sensor lead wires, distributer, injectors,fuel filter, spark plugs I even check the wires from the ecm to the coolant temperature sensor and the wire is ok I tried everything except the ecm can It be the ecm can anyone help me

<p><b><span>2.2) <span> </span><u>ECT - Engine Coolant Temperature </u>(sensor)<u></u></span></b><br /> <p><b><u><span><span> </span></span></u></b><br /> <p><b><span>What is it?</span></b><span> This is small electrical device for measuring the coolant temperature in the engine</span><br /> <p><span> </span><br /> <p><b><span>Where is it located?</span></b><span> It is usually located on the engine near to the thermostat housing.<span> </span>The ECT is sited on the 'hot' side of the thermostat so that it senses the coolant/engine temperature before the thermostat opens and allows coolant to flow through the radiator.</span><br /> <p><span> </span><br /> <p><b><span>How does it work?</span></b><span> Modern temperature sensors consist of a thermistor in a sealed unit.<span> </span>As the temperature rises the electrical resistance varies proportionately; some thermistors increase their resistance with temperature (PTC - positive temperature correlation) whilst others decrease their resistance (NTC - negative temperature correlation).<span> </span>When the engine is cold at start up the coolant sensor sends an appropriate signal to the ECU.<span> </span>The ECU responds by increasing the length of the injection cycles to enrich the combustion mix.<span> </span>This is an electronic equivalent of pulling the 'choke' out on a carburetor.<span> </span>As the engine warms up the signals from the coolant sensor cause the ECU to shorten the injection cycles making the fuel mix progressively leaner.<span> </span>The process of coolant sensor and ECU interaction explains why engines have a slightly faster idle when starting cold than when running hot.</span><br /> <p><span> </span><br /> <p><b><u><span>Symptoms of faulty coolant sensor</span></u></b><br /> <p><b><span>Associated OBD2 error codes DTCs: <span> </span>P0115 - P119; P0125, P0126, P0128</span></b><br /> <p><b><u><span><span> </span></span></u></b><br /> <ul> <li><b><span>Poor starting</span></b><span> - If the coolant sensor reports in error that the engine is warm the ECU will not enrich the fuel mix at ignition.<span> </span>The engine will falter at idle if it is not given additional help by the driver by pressing on the accelerator pedal to maintain speed.<span> </span>Once the engine has warmed up the engine will behave correctly.</span></li> <li><b><span>Fast/erratic idle, Poor fuel economy - </span></b><span>conversely if<b> </b>the coolant sensor reports in error that the engine is permanently 'cold' the ECU will keep the fuel mix rich.<span> </span>This is OK at start up but will become more noticeable when the engine is hot; idle will be fast and lumpy.<span> </span>Fuel consumption will be high due the permanently rich fuel mix set by the ECU.<b></b></span></li> <li><b><span>Excessive emissions - </span></b><span>the enriched fuel mix delivered in response to ECT signal error causes the exhaust to be heavy in un-burnt hydrocarbons.<span> </span>This often results in 'emission test' failure.<b></b></span></li> </ul> <p><b><span> </span></b><br /> <p><b><span>How to check? </span></b><span><span> </span>Most often the <b>coolant sensor</b> is quite separate to the <b>temperature sender</b>, so a correct read-out on the dash board does not necessarily indicate correct sensor function. Using<b> </b>a voltmeter the resistance across the electrical terminals on the sensor can be measured.<span> </span>By removing the device from the car and putting the end of the sensor in a pan of hot water it should be possible to see an immediate change in resistance, it does not matter so much that the resistance goes up or down but that there is a discernable change with change in temperature.<span> </span>Generally high resistance equates to cold temperatures and vice versa. If there is no resistance change commensurate with temperature change then the sensor is at fault.<span> </span>If there is simply no resistance measurable (open circuit) then the sensor is at fault. If the sensor is working correctly check the connector, the wiring and the wiring insulation for faults and possible shorting.</span><br /> <p><b><span> </span></b><br /> <p><b><span>How to fix?<span> </span></span></b><span>Replace if found faulty</span><br /> <p><span><br /></span><br /> <p><span><b>NEXT 3.1) CKP - Crankshaft position sensor</b></span><br />

1991- 2000 Saturn S-series owners sometimes complain about rough starts or rough idling. In some cases it's a cause for the car not to start even though the starter is fine and the battery is at it's best. There is a simple reason for this that most owners don't know about.


So What's The Deal?

It's simply actually. It's called the Engine Coolant Temperature Sensor (ECTS for short). The what?! It's a basic thermoresistor (a resistor that changes it's resistance based on temperature) that is in a place where coolant flows past it. It tells the car's PCM (computer) how hot or cold the coolant is. Of course when you let your car sit overnight and come out in the morning to start it the coolant temperature is close to ambient temperature. When the car is started the coolant starts getting hotter and the ECTS tells the PCM the temperature as it's rising until eventually at full operating temperature.


Then What's The Problem?

Saturn used a plastic tipped sensor which is prone to cracking because of the constant heating and cooling cycles it sees. Coolant sees anywhere from -10 degrees Fahrenheit to 230 degrees Fahrenheit as does this sensor. So you can imagine plastic wasn't the best idea. It gets worse though. When this sensor cracks it allows coolant to flow to it's two wire connector and thus ruining the connector with old gunky coolant.


So This Has to Be Expensive and A Long Procedure To Fix...

Not at all! It's actually a very cheap sensor and in an easy place to replace. The nice part is that this was remedied in 2001 when Saturn switched to a brass sensor that does not have this problem. The part can be found at a local AutoZone or Advanced Auto or simply from you Saturn dealer (if one is still around). Ask for a Engine Coolant Temperature Sensor and when they come back check that it is brass (which is pretty obvious because the plastic tipped one has a very smooth rounded leading edge while the brass is more flat on the top).

The sensor is located just under and behind the upper radiator hose entrance into the head (might have to remove the intake tubing). It has a two wire sensor going to it. Check to make sure you're not changing the one that goes to the dash gauge on early S-series (91-95).

Remember to do this when the car is off and cold.

This should fix your rough starts and rough idling. If it doesn't, check the connector to make sure it isn't gunked up and put it all back together.