Vs ute ecotec losing its idle when cold

[sv8vy]

Hello. My vs ute has been causing me a bit of pain lately. Okay, so when i start it up in the morning it sits just above stall (maybe 4
300-500rpm). By the time i back out of my shed it holds its idle but sounds like its pulsating, I have cleaned the throttle body, replaced crank angle sensor, am hoping someone may know what this is? Perhaps another sensor? Perhaps something to do with the choke? When is hot it sometime holds around 700rpm, but not always. Performs nicely and runs smooth on the road.

 

[jeepyrocks]

Did you remove the IAC valve from the throttle body and give it a clean? It controls the idle and can gum up. Remove, clean, disconnect battery while doing it so its reset and ready to go once you start up. Bring revs to 3k for ten seconds for it to relearn (though really a decent drive will usually do the trick)

 

[sv8vy]

Yeah mate i have pulled out the IAC valve and cleaned it up, functions well in hand. I have also checked all coils and plugs, which are all firing a healthy blue spark.
It started about 6 weeks ago, all of a sudden, as in was running fine, parked up for an hr or 2 than it wouldn't start. It requires giving it a bit of of gas to start now, then if i slowly take my foot of the gas it will just hold onto to revs and not stall. The idle will pulsate between 3-6rpm until the temp gauge starts to show a reading, 10mins or so, then it will idle flat, but still less the 700rpm.

 

[BowTie]

Pcv sticking shut when cold? How old is it?

Smooth idle needs consistent crankcase ventilation. Clamping the tb to manifold hose momentarily simulates a blocked pcv and should drop the revs until the iac compensates.

If clamping it momentarily has no effect, pcv is not venting to plenum.

 

[sv8vy]

It's a 99 model. Problem still not resolved. What would also make the fans pulsate on and of when cold?