plz explain i mean i love to learn i thought all the temp sensor was for was to tell me if the truck was trying to overheat?

 

PCM needs to know what temp the engine is, so it can maintain the correct fuel/air ratio. Colder air is denser, hence, carries more oxygen. Also used for engine warm up. PCM adds fuel when the engine is cold, so, it warms up faster. Colder it is, the more fuel it adds. A failed ECT sensor tends to tell the PCM that it is -40* out, so the PCM DUMPS!!!! Fuel, so enough can atomize to get a burnable mixture. If it isn't really that cold.... you run pig rich, and run into all sorts of interesting problems.

 

+10 on what heyyou stated for the ECT (engine coolant temp) sensor... I've dealt with that myself... Why wasn't your check engine light on? If it was, and you neglected to mention; please do so in the future, as it gives us valuable diagnosis information. If it wasn't on... It should have been, might wanna check and see if the bulb that illuminates it is burned out.

The idle air control motors function is to let air pass through the throttle body at idle, when the throttle plates are closed... you probably didn't need to replace it, a thorough cleaning is enough to solve most problems with it.

Driving with a dirty one impedes airflow at idle. I believe the PCM recognizes this, and raises idle to compensate (thus burning more fuel at a stop light). However, this conclusion is based mainly on speculation of what I think would happen in this circumstance, and therefore, may not be completely true.

 

ok thanx guys and my check engine light was on im sorry :P, but yes it was on everything yall are telling adds up i cleaned the idle/air now it works fine does not idle up idles right were it spose to again everyone thank u for your input i now know that a temp sensor is just more than a way of knowing how hot the truck is getting but alos communicates with the PCM makes sense now why the PCM needs to know these things thanx guys yall are the best of the best to be such an unofficial site