Rough idle when cold.

[vortex2450]

Lately I've noticed that my SHO idle's rough when I first start it if it's been sitting for long enough to get cold (>3 hours).

When I start it it will try to idle for a couple seconds and get down to about 600-700 rpms and "lope" along. It will continue to do this for about 15 seconds then the car will rev up to 1500 rpms and hold there for another 30 seconds before it slowly lowers back down to an idle and which point it will idle smoothly.

Also, if I begin to drive before the car has a chance to go through ^this little procedure when I can to a stop it will do the 1500 rpm idle and so forth over and over again until I let it go through it's cycle.

I checked my plugs, no unusual residue, gaps are good. No oil/water in the wells, and coil pack swap didn't change anything.

No KOEO codes but I haven't ran a KOER test yet.

Ideas? CPS? CID? DIS? 02 Sensor?



-Josh

 

[SHOYAY]

I'd lean towards a bad idle air control. Maybe even bad air temperature sensor , vacuum leak, throttle position sensor. Was the battery unhooked for a while and now the idle reset procedure needs to be done?

 

[vortex2450]

I'd lean towards a bad idle air control. Maybe even bad air temperature sensor , vacuum leak, throttle position sensor. Was the battery unhooked for a while and now the idle reset procedure needs to be done?

It could be the air temp sensor/TPS. I checked for vac leaks, none exist.

Now as stupid as it may seem I didn't do the idle reset procedure when I relocated my battery and that may be the issue because once it's idling normally it doesn't have any more issues.

-Josh