Since the "search" function is on temporary hiatus, I am going to open this thread. If you can direct me to a previous thread that can help me, I would appreciate it.

Ok, so a while back (read before Xmas) my truck began this cold morning start problem. Basically, it wouldn't hold idle until the truck reach operating temperature. Took it to the dealer, who couldn't replicate the problem but suggested that the problem might be the idler. I sat on the issue, and it went away for a while. Then it came back worse, where it would reach operating temp. but still would stall if I let the rpm's drop below 500. Again, it went away.

A couple week's ago, I noticed the coolant level was below the "cold fill" level. So as the manual suggested, I filled it up to the aforementioned level (using 50% water/coolant). Then last week when I got out of class, I noticed coolant leaking underneath the truck. I drove it home carefully (40 minutes one way) and looked under the truck after it settled for an hour: no more leaking. Checked the radiator hose, and it was still pressurized, so I ruled out a leak.

The last 2 consecutive days, the cold morning start problems have resurfaced. This time however, it feels like the power is being sapped fairly significantly. On top of that, I started it in the afternoon and it idled without hint of a problem.

So WTF is going on? I was reading about the ECT, so I am steering in that direction. Any help will greatly be appreciated.

 

ttt

 

It doesn't sound like an ECT (Engine Coolant Temp.Sensor) issue. This is the one that tells the computer that you've reached normal operating temp so it adjusts the fuel mixture. Resistance decreases as coolant temperature increases. There are 2 temp sensors and both are located at the front of the engine. One is the ECT and the other is the Engine Temp Sensor that goes to the instrument cluster. The ECT is mounted at a 45 degree angle and the other temp sensor is mounted vertically. I think that if it were a faulty ECT, you're engine would idle high and run rich all the time because the computer would think it's cold.

All of the computer control sensors are simple to test. You'll need a digital mutimeter and 2 leads. What I use for leads are large saftey pins. Use the manual to determine which wires are hot and ground then plug the safety pins into the back of the sensor and connect the hot and ground wires from the multimeter. The Haynes and Chilton's manuals specify the resistance of each sensor.

I'd suggest that you test resistance on all of the sensors and if everything comes back normal, move onto mechanical issues like the DPFE, EGR, IAC.

Don't forget to test the HO2 sensors as well.