Snap-On Diagnostics DGA 1000, Руководство пользователя

Страница: 61 / 116

Vehicle Testing
3-13
Catalytic Converter Test
The Catalytic Converter Test is performed manually and is fully
under the operator’s control. This allows the test to be run even if
engine RPM measurements are not easily accessible. In that case,
follow the screen prompts to complete the test. The test must be
completed within five minutes after vehicle warm-up or the
catalytic converter may cool and the test results may be invalid.
✓
This catalytic converter test does not identify a restricted
catalytic converter.
What the Catalytic Converter Does
The catalytic converter reduces normal "engine-out" (pre-catalytic
converter) pollutants (
HC , CO and NO
X
) to acceptable levels.
Anything that causes the engine-out pollutants to exceed normal
levels reduces the effective life of the catalytic converter. The
catalytic converter requires precise control of the air/fuel ratio to
operate at peak efficiency. Anything that disrupts the air/fuel
ratio—such as an engine that burns oil—reduces catalytic
converter efficiency and potentially increases failure.
How the Catalytic Converter Test Works
This test requires injecting a specified amount of propane through
a preheated catalytic converter. Use the propane enrichment
assembly, part number EAA0259L00A, to inject propane upstream
of the catalytic converter. The amount of propane flow depends on
the engine displacement and whether the vehicle is equipped with
a single or dual converter. Within the preheated converter, most of
the propane is oxidized into
CO
2
. However, a small amount of
propane passes through the converter unchanged. It is possible to
determine catalytic converter efficiency by measuring the amount
of
CO
2
and the level of unconverted propane.
: Catalytic Converter Test Overview