I have a '97 v-8 Lariat pushing 90K. Acts fine, 'til I need to start in the morning when its below 10 degrees. Starter turns but engine won't fire, sometimes I can get it to go by giving some gas, or starting it 2-4 times. Friday, I said screw it, and went back to bed for an hour--came out started up just fine. PCV valve was cleaned a couple years ago--helped some, replaced battery, had antifreeze checked, spark plugs and wires only a year and half old. I was thinkin' might be sensors, or needs a new PCV valve....Any suggestions?

 

possible the i.a.c valve might need a cleaning.do you drive around with the low fuel light on like me??? lol. thats not good especially in the winter. ive had a few no start freeze ups when it gets real cold up here in mass.

 

When an engine is cold, The computer is in what we call open loop. That basically means that the engine ignores the O2 (oxygen) Sensor to deliver heavy fuel upon start up. To calculate Closed loop, where the ECM enters fuel management, the computer looks at Coolant temperature, Throttle Position, Engine Load (MAP sensor) Mass Air flow, Intake air temperature, and the crank sensor. My bet is on the Coolant temperature sensor. This is essentialy a thermistor, which is a sensor that as it's heated, the resistance goes down. If you unplug this sensor, the computer will see it as a hard malfunction, and completely ignore any input from it, and rely on factory programmed defaults. If you unplug it, and the truck starts up just fine, Thats the problem. To ensure your not changing the sensor for a broken wire, Use a voltmeter and ensure that you have a 5V Reference signal to the sensor, and a good ground as well. This will cause a Check engine light, So once you've unplugged it, Turn the headlamps on, and remove both battery terminals for 5 minutes. This is the backyard code clearing technique. The truck may act weird until it re-learns itself (usually 2-3 drive cycles) Get back to us, let us know!

-Jimi