when the outside temps start gettin colder.. probbaly 40* or lower... when i start my truck up for the first time on the morning, itll surge (idle goes up and down) for probaly 30seconds maybe 45.. then shell idle jsut fine.. any ideas what this could be?

 

Wait so is it cranking properly or no?

 

oh yeah she starts up just fine, except once shes running, the idle surges up and down, like from 700rpm to like 1000rpm and back down to like 700rpm.. does that for like i said usually 30-45seconds and then she idles jsut fine, and everytime i start it up there after for rest of day it doesnt surge.. only when being started for the first time each day..

 

No check engine light? I would think intake manifold gasket, but you'd see a lean code.

 

nope no lights on... its really weird.. i for the life of me cant figure it out..

 

When was the last time you cleaned your MAF and TB?

 

the MAF was not to long ago.. maybe 4months.. ill try the TB tomorrow and see if that helps any..

 

What year is the truck??? If it's a 99-02 you will find the IAC valve is partially plugged up with a carbon suit build up.

The IAC valve is what controls air flow for idle stability with the blade in the closed position. The factory parameters that control this are based on the passage being clear. When the passage becomes restricted the factory values can not compensate enough and the idle searches high and low trying to find a stable ground.

Pull the TB and clean the passages on the back side. Be carefully with the TB Position Sensor and the IAC Valve as they are basically electronic switches and can be damaged if you overextend them.

 

awsome, ill give that a try today! thanx for the input

 

I'm gonna say its a parameter in the tune effected by IAT's that needs some adjustment.