Cold start idle surge ?

[Operation.stinger]

Hey all was just curious as to what could be causing my 3.3 to have an idle surge when warming up. It’s been happening every so often and I’m just curious as to what this is. I’ll start it up let it sit for a few min till it drops to about 1000-1300 rpms and then it will do it surging from 1000-1300 rpms then after its dropped to its normal idle of 700-800 it won’t anymore.

 

[Snicklefritz]

Sounds like the normal higher RPM when started up cold. In c. half a minute or more the RPM will drop to 1100-1300, and that's when I roll. Ima pretty sure that my cars don't idle below 1000.

 

[Thomby]

I’ll start it up let it sit for a few min till it drops to about 1000-1300 rpms and then it will do it surging from 1000-1300 rpms then after its dropped to its normal idle of 700-800 it won’t anymore.

By surging do you mean revving up and down? Or just taking a couple minutes to reduce rpm?

Ima pretty sure that my cars don't idle below 1000.

My idle once warmed up is pretty steady at 600 (~595-610 in the JB4 realtime view).

 

[Operation.stinger]

By surging do you mean revving up and down? Or just taking a couple minutes to reduce rpm?


My idle once warmed up is pretty steady at 600 (~595-610 in the JB4 realtime view).

Yes revving up and down. It’ll do it 3-5 times then go back to normal

 

[Thomby]

Yes revving up and down. It’ll do it 3-5 times then go back to normal

That's odd, sounds like it's hunting. Have you checked ODB codes? I wonder if it's losing a temp signal or something.