Surging Engine when Heater is on when its cold out

[PearlWhiteLTD]

When the truck is starting to warm up, as well as im trying to, I turn the heater on before it hits its full heated up temeperature. It seems to surge, and drop in RPMS a bit and then back up and down etc. It goes away when I turn my heater off, it also only happens in the cold. Any ideas?
Thanks Guys

 

[NHale623]

Test your ECT sensor. You could also disconnect your AC compressor and see if the problem goes away.

 

[PearlWhiteLTD]

Where is the ECT sensor, as well as what does it stand for?

 

[NHale623]

ECT = Engine Coolant Temperature Sensor.

In order to help you find it, you need to specify which engine you have.

 

[aldive]

Have you checked the thermostat?

 

[PearlWhiteLTD]

I have not checked the thermostat yet. Do you think that could be the issue? It has a deep BASS type groan when it surges. Sounds like a car next to me has its BASS up. I had the IAC replaced at Ford not to long ago.
(my car wouldnt stay running unless I had kept my foot on the gas) I have the 1999 SOHC 4.0L v-6 fo the ECT location comment...

 

[NHale623]

The ECT is located in the intake manifold, just to the left of the throttle body (as you're standing at the front of the truck). It'll have a grey connector with two wires. One wire should be grey with a red stripe, the wire should be light green with a red stripe.

http://www.explorerforum.com/forums/showthread.php?t=164878&highlight=ect

This thread will have a chart in it that contains the resistance/volt values you should be seeing for a given temperature.

 

[PearlWhiteLTD]

Just realized the surging happens with or with the heater on. It sounds like it is dropping in RPMS but sure enough, its not it just seems like it. It just gets a DEEP BASS sound and it comes and goes. It goes away if I tap the gas. Then it comes right back. ITs annoying at most, but I would like to solve the issue. IT even rattles my exhaust quite a bit.

 

[PearlWhiteLTD]

PS i had the IAC replaced 1 month after I bought it (May 2003) at a ford dealership. It seems like that issue could be coming back? I dont know. When I had it replaced, it wouldnt even stay running unless I held the gas a bit.