Hey guys, every time I start my truck when it's cold it immediately stalls out. I have to rev it for a little while or just double foot the gas and break while I drive to get it warmed up. Once it's warm I don't have a problem. I can turn it off then start it and I'm still good. I'm starting work on it tomorrow and was thinking about cleaning the throttle body and checking the Idle Air Control motor first. Any ideas or advice? Thanks!

 

Does it idle okay for the first minute or so? Or is it flaky right from the start?

If it's flaky right from the start it's likely the IAC you're fixin' to clean. If it idles okay for the first minute or so, it's more likely the pre-cat oxygen sensor.

 

Its flaky right from the start. Thanks alot for the advice.

 

How do I know if the IAC needs to be cleaned or replaced? Also, my friend's coming over with the code reader. I heard that would help.

 

Code reader's always a good start. Sometimes things work just enough to keep the pending codes from setting the CEL.

The best way to know if the IAC needs cleaning is to haul the little bugger out and look at it -- just don't push, pull, or twist the pintle. And as long as it's out you might just as well clean it up nicely, and then rise to the challenge of cleaning its bore in the throttle body. If you've got a mirror, a flashlight, sensor safe cleaner, some cotton swabs, and a relatively high pain tolerance it's doable without removing the throttle body from the manifold.

When my IAC was acting up, it sometimes hung up when the engine was warm, but when it was cold and particularly when it was damp and cold it'd hang up until the engine warmed. My hypothesis is that the humidity causes the carbon and crap to swell and cause interference, but I'm not really inclined to do the science to prove it.

Anyway, be sure to disconnect the negative terminal of the battery when you begin work so the PCM will reset and feel a need to recalibrate the IAC. It'll go quicker if you can find a nice stretch of road where you can cruise at 40MPH or so to give the PCM the opportunity that it looks for to perform the calibration.

 

 

I removed the throttle body and the IAC motor and CLEANED them, I'm talking sparkling clean. Both were caked with carbon build up. Put everything back together and it was still doing the same thing. I am 99% sure the problem is the throttle valves aren't open enough. If you hold the valves open when you start it, it starts up fine, then stalls when you close it. What do you think? And how can I fix that?

Thanks for all the help!

 

Are you talking about the buterfly valves? if so that really sounds like the IAC motor has gone out, the butterflys should not be open without your foot on the gas pedal

 

Yes, the butterfly valves, sorry I'm new to all this. They're not open unless you have your foot on the gas. My dad was using his hand to turn the positioning which would increase the RPM's. Isn't that the same thing as putting your foot on the gas. I will add a picture of how open they are in the afternoon, I have work in the morning.

 

Here's the pictures of what the butterfly valves look like during idle. I just took it for a long drive to re-calibrate it like Unregistereduser suggested. Do you think that was the problem? Even though I did the work on it, it hadn't re-calibrated yet?