When the outside temp is cold the car runs mostly fine, but when the outside temp is warm the car runs erratically. i lose power and the car eventually dies. then it needs to be off for 10 minutes or so to start again. i've been told it's an IAT (air temperature) sensor.
is this accurate and is it something i can replace myself? i'm not a car genius but not completely dumb about it either.
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Re: possible bad IAT sensor
I doubt it's the IAT in the air cleaner tube. Go to an auto parts store and ask them to scan your car for fault codes & see if one says a bad IAT.
It may be the start of your fuel pump in the fuel tank failing. Need to check pressure to see if maintains 40 psi. Gauge connects to fuel rail shrader valve.
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Several conditions could be the cause of your problem.
Bad MAF (Mass Air Flow) sensor - often responsible for erratic idling
Bad TPS (Throttle Position Sensor) - controls idle speed under all conditions ie warm, cold, + with A/C running.
It's possible to diagnose further by getting a diagnostic test done. Most chain auto parts stores will run a free diagnostic test to obtain a OBDII code (these codes specify which components are either failing or not responding) It is possible that a combination of both the MAF and TPS are contributing to your problem. If the car will idle when cold and only wants to stall once warm and under way, it's more likely than not to be the TPS.
I recently bought a Saturn for my daughter. The car had a hard starting problem (it crank and crank before firing). I got on this site and one possible solution was the temp sensor for the computer. The original unit has a plastic tip that cracks and lets coolant into the electronics. As a temp related problem I would suggest you check or change the temp sensor. At my local Auto Zone the part cost $8.99, so its not an expensive gamble.
Could be a problem with your intake air temp sensor or your coolant temp sensor. The most likely would be the coolant temp sensor. It may be reading cold and will make it run good as the engine is cold but as it warms it is not adjusting the air fuel ration to the proper levels making it run rough hot
It sounds like an engine temp sensor is open.. When your engine is cold or anti-freeze is cold your ECU or ECM gets a signal from the temp sensor for cold engine start. It would make sense that it works fine when hot because the resistance on the sensor is a lot lower. Take an ohm meter if you have one and check the resistance across the temp sensor pins. When the engine is cold the resisitance should be really high. Start and warm up your car to normal temp and check it again. It should be a lot lower now. If not replace it. Hope this helps.
It could possibly be your temperature sensor. I had a Buick with the same problem. In winter, it ran fine. When the weather warmed up, the car would sputter and die. A defective temp. sensor will cause your car's ECM to mis-read the coolant's temp. So it will adjust your fuel input as if the outside temp. was -30,causing an over-rich fuel mixture.