Truck horrible idle in cold weather.

[kgalvin131]

I have a 2002 Silverado.

When the temperature drops below 40 degrees my truck revs up to 2000 rpm when I first turn it over. Then it drops, flutters, and dies. I have to keep the on the gas to keep it alive.

Took it to the automotive shop thinking it was the intake manifold gasket. But he tested it and it wasn't that.

The only code that keeps coming up is P0440 EVAP system malfunction. He say's something about the fuel canister.?

What else could cause this issue, I already changed the full pump in the last year and recently changed the fuel filter

 

[Chuzz]

It could be something as simple as a defective gas cap. That'll throw a code. Also, how many miles are on it and are the plug wires original? Cold weather will really screw with your plug wires if they're old. Doesn't matter how good they look, they do break down over time.

 

[Suburbanized]

gas cap wont cause bad idle imo. check the MAF, TPS, TB, IACV, coils, and run a fuel cleaner throught the system to clear all of the crap that is built up over time.

 

[zora]

Do you have a check engine light on?

 

[Chuzz]

I wasn't insinuating that a gas cap would cause his bad idle, but it will sure throw a CEL. The idle could be any of the things you mention, that's for sure.

 

[Suburbanized]

OK got it.

The only code that keeps coming up is P0440 EVAP system malfunction. He say's something about the fuel canister.?

zora, it does have a CEL^^

 

[zora]

Guess I missed it. The code shouldnt cause cold weather problems, I'm with your prior suggestions about TPS, etc.

http://www.obd-codes.com/p0440

 

[Suburbanized]

Give the ECU & Fuel ECU some thought as well.

 

[Reesey]

IAC, TPS, engine temp sensor, could be a plethora of things. I would check the IAC first since it stays "alive" when you keep your foot on the gas. The Idle Air Control could be dirty and just need to be cleaned with choke and carb cleaner. That will take a little time but save you from having to spend money outside of the can of cleaner. Its worth trying before you just start throwing parts at it. If you clean it though be sure not to pull or push on the plunger. That will destroy the IAC. You will also want to clean out the housing where the IAC is bolted to. I use the cleaner and q-tips when I do mine. Works like a charm. Also try not to spray the electrical components with the cleaner.

 

[Chuzz]

This thread is over a year old. I wonder if he ever got it fixed?