Chevrolet 2007 TrailBlazer Owner's Manua page 114

Starting Procedure
1. With your foot off the accelerator pedal, turn
the ignition key to START. When the engine
starts, let go of the key. The idle speed
will goes as your engine gets warm. Do not
race the engine immediately after starting
it. Operate the engine and transmission gently
to let the oil to warm up and lubricate all
moving parts.
Your vehicle has a Computer-Controlled
Cranking System. This feature assists
in starting the engine and protects
components. If the ignition key is turned to
the START position, and then released when
the engine begins cranking, the engine
continues cranking for a few seconds or until
the vehicle starts. If the engine does not
start and the key is held in START for many
seconds, cranking stops after 15 seconds
to prevent cranking motor damage. To prevent
gear damage, this system also prevents
cranking if the engine is already running.
Engine cranking can be stopped by turning
the ignition switch to the ACCESSORY
or LOCK position.
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Notice: Cranking the engine for long periods of
time, by returning the key to the START position
immediately after cranking has ended, can
overheat and damage the cranking motor, and
drain the battery. Wait at least 15 seconds
between each try, to allow the cranking motor
to cool down.
2. If the engine does not start after 5-10 seconds,
especially in very cold weather (below 0°F
or −18°C), it could be flooded with too much
gasoline. Try pushing the accelerator pedal all
the way to the floor and holding it there as you
hold the key in START for up to a maximum of
15 seconds. Wait at least 15 seconds between
each try, to allow the cranking motor to cool
down. When the engine starts, let go of the key
and accelerator. If the vehicle starts briefly
but then stops again, do the same thing.
This clears the extra gasoline from the engine.
Do not race the engine immediately after
starting it. Operate the engine and transmission
gently until the oil warms up and lubricates all
moving parts.