Exhaust Restrictor (Engine Warm-Up) - GMC TopKick 2007 Owner's Manual

Automatic High Idle System
The automatic high idle feature will engage
whenever you start your vehicle and the engine is
below the preset operating temperature. This
will help decrease engine warm-up time.
On vehicles that have the Caterpillar
engine you may have an exhaust restrictor that
will operate in High Idle mode. The exhaust brake
switch must be on for this feature to operate.
See Diesel Engine Exhaust Brake on page 109 for
more information.
Idle speed will then return to normal under any of
the following conditions:
•
The engine reaches the preset operating
temperature or has been operating for at least
10 minutes.
•
The brake pedal is pressed.
•
The manual transmission clutch pedal is
pressed or, if the vehicle has automatic
transmission, it is shifted from NEUTRAL (N)
or PARK (P).
•
The vehicle speed exceeds about
5 mph (8 km/h).
•
The throttle is pressed.
Exhaust Restrictor
(Engine Warm-Up)
Exhaust Restrictor
If your vehicle has a Isuzu 6H or Caterpillar
® Diesel Engine, it may have a feature called
diesel
an Exhaust Restrictor (NPE), which uses an air
actuated valve in the exhaust system to restrict
exhaust gas flow which enhances the engine and
heater warm-up.
Automatic Quick Warm-Up
If your vehicle has a DURAMAX
has a feature called an Automatic Quick Warm-Up,
which uses the turbocharger to restrict the exhaust
gas flow which enhances the engine and heater
warm-up.
In both systems, exhaust restrictor or automatic
quick warm-up, the cold temperature high
idle feature elevates the engines idle speed, up to
1500 rpm, and restricts the exhaust gas flow,
when outside temperatures are below 32°F (0°C),
and the engine coolant temperature is below
certain levels. This feature enhances heater
performance by raising the engine coolant
temperature faster.
®
®
6600 engine, it
105