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Discussion Starter · #1 ·
Where are all the sensors located that check for temperature? My car will not run when its below freezing trying to figure out what sensors are checking for air temperature other than the intake air temp sensor (IAT)?
 

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As mentioned in the reply to your initial thread, the IAT is on the intake tube, the ECT is under the thermostat housing as it goes into the lower intake.

They're pretty reliable sensors, and you can monitor them realtime with a $13 OBD2 scanner and app. Occasional wire breaks are the only things that tend to be issues for them. If your engine is having coolant leak issues, it's not going to always have enough to properly immerse the ECT sensor and report it properly for fueling adjustments based on engine temp. That's still what you need to dig back in and address, based on previous posts in the original thread.
 

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Discussion Starter · #3 ·
Understand that but I have driven this vehicle since march without a single drop of coolant lost until its gotten down below 32 degrees. I have been monitoring temperatures closer when I drive it as winter is approaching. I have driven this vehicle a number of times in 34 degree weather flawlessly. But the very FIRST time it was at or below 32 degrees coolant gets into the combustion and car will not run. Trying to locate sensors to see what could be causing the car to only have this issue at freezing temperatures.
 

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There's a plethora of tables in the computer that are constantly in flux while the car is running. This is why we monitor about 15-20 parameters while scanning in real time, including adding some extras when we get more into the details with modding (WBO2, fuel pressure, oil pressure, etc.).

You can either use a single data point and guess at what's going on, or drop the $12-15 and start seeing what's going on with fuel trims, O2 readings, along with anything else you want. Best part is that you can use it to read/clear codes on yours and others' cars/trucks in a pinch. Information is what gets you out of the dark, so that your efforts under the hood have a little more guided direction, even if you get more certain of what's needed.
 

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Long & Short Term fuel trims on Bank 1 (FWD 3800 fueling is only based on the 1st O2 sensor data combined from both sides of the engine)
ECT
IAT
RPM
TPS
O2 B1S1
O2 B1S2 (if newer than 2000, due to a catalyst test GM started dumping fuel to try... See, this is why you keep discussions in a single post, because I no longer have the context of your original info to help offer info. I could open it in a new tab, but that's more effort than my toilet browsing is gonna get right now.)
Spark Advance
Ignition/PCM/system Voltage (whichever)
KR
MAF hz
MAP kPa
Injector pulse (msec) or duty cycle (%)

Should get you a decent view of what's going on. Can add cam/crank sensor signals, if you think a timing issue is occurring, but it sounds more like fuel, coolant, or possibly wiring.
 
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