If your doing it on purpose then DON'T.
If the engine is doing it via the computer you need to take it into the shop and have them look at it. There seems to be a bad sensor telling the computer wrong information. Running at a high rpm when the motor is cold and with no load is not good for it.
Often a knock when cold is caused by piston slap, which is pistons rocking in the cylinders until they expand in size when the engine warms up.
it could be the coolant temp unit. it senses the engine temp and adjust the throttle occordingly so the engine can easly worm up to operating temp. when i first start my 1990 tracker up, it will idle at around 2,000 rpm until it warms up then it will idle at around 700 rpms. automatic idle switch.Nah. Supprised that your engine hasn't 'gernaded'! Something's mechanically sticking in WOT (wide open thottle) when you first start up; like the throttle plate/accellerator cable???
No, the O2 sensors are out of the "loop" until the engine warms up.
bad seal/ gasket around fuel injector or intake manifold. as engine warms components expand and form a seal.
this is caused from piston to cyl wall clearance when engine warms up the pistons exspand and the noise is less. DON'T WORRY ABOUT IT
i have a 2000 dodge work van 318 engine when i start in the morning it stalls several times until it warms up then ok
Valves tapping?
belt
The 2006 Ford F2 50 diesel engine might have a bad fuel injector. The injector can cause the engine to not run properly, until the engine warms up.
Try checking the trans fluid. The level of the fluid drops when the engine becomes hot. Check the fluid with the engine idling with the trans in park.
because the engine is cold. after it warms up the light goes off. Cute! But what causes the blue light to come back on even after you've been driving for a while?
Most likely mapp sensor top of air cleaner