Hey guys I have a 2000 blazer with 4.3. I have replaced the timing gear, plugs, cap & rotor, checked fuel pressure and im out of ideas. In the morning when its like 40 degrees or less out it doesn't like starting, I have to hold the pedal to the floor before turning the key or I'm pretty much screwed. Now that its warm It isn't a problem but another has developed. Now I start it and it randomly misfires BAD. I can hardly drive it if the temp outside is less than 70-75. it was 80 for a couple days and I only had trouble in the morning when it was like 60 out.

I have been told there is a sensor that measures the temp outside and adjusts fuel accordingly. However no one can tell me where it is or if it would cause the problems im having.

Please help, I really like my blazer.

 

"I have been told there is a sensor that measures the temp outside and adjusts fuel accordingly. However no one can tell me where it is or if it would cause the problems im having. "

IAT or Intake Air Temperature Sensor

Is located on the air intake flex tube, with the grey harness connector, Shown in this picture



The Intake Air Temperature Sensor (IAT) is used by the ECU to determine the temperature of the air entering the engine. This is used in conjunction with the MAP sensor to determine the density and volume of air entering the engine to make the proper fuel adjustments to maintain the correct air/fuel ratio. The Intake Air Temperature Sensor is a temperature dependent resistor (thermistor). The resistance of the thermistor decreases as the intake air temperature increases.

 

Thank you!!!

Wouldn't know how to test it would you???

 

DIAGNOSING THE AIR TEMPERATURE SENSOR
A faulty air temperature sensor may or may not set a code and turn on the Check Engine light. If the sensor circuit is open or shorted, it will usually set a code. But if it is only reading high or low, or is sluggish due to old age or contamination, it usually will not set a code.
A quick way to check the air temperature sensor is to use a scan tool to compare the air temperature reading to the coolant temperature reading once the engine is warm. A good air temperature sensor will usually read a few degrees cooler than the coolant sensor.

The sensor's resistance can also be checked with an ohmmeter.
Remove the sensor, then connect the two leads on the ohmmeter to the two pins in or on the sensor’s wiring connector plug to measure the sensor’s resistance. Measure the sensor’s resistance when it is cold. Then blow hot air at the tip of the sensor with a blow drier (never use a propane torch!) and measure the resistance again. Look for a change in the resistance reading as the sensor warms up.
No change in the sensor’s resistance reading as it heats up would tell you the sensor is bad and needs to be replaced. The sensor reading should gradually decrease if the sensor is a negative thermistor, or gradually increase if it is a positive thermistor. If the reading suddenly goes open (infinite resistance) or shorts out (little or no resistance), you have a bad sensor.