RayTek AUTOPRO Manual De Instrucciones página 18

Engine Performance (Cont.)
verify ECT and IAT sensor inputs, a scan tool or
other data device with proper software installed
will need to be connected to the vehicle to enable
viewing of the actual ECT and IAT sensor tempera-
ture readings.
Start engine and run until normal operating tem-
perature of 85-105°C (190-220°F) is reached and
temperature stabilizes. For vehicles equipped with
electric cooling fans, ensure fans cycle on and off
three times prior to checking temperatures.
To verify ECT sensor temperature, monitor ECT
sensor temperature reading on scan tool. On most
vehicles the ECT sensor is threaded into the cool-
ing system, near the thermostat. Measure tem-
perature where ECT sensor threads into engine.
Compare temperature readings. If temperature
readings are not approximately the same, check
for the following before diagnosing:
n Damaged ECT sensor, connector or wiring.
n Air in cooling system (possibly from not being
properly bled).
To verify IAT sensor temperature, turn engine off
and ignition on. Monitor IAT sensor temperature
reading on scan tool. On some vehicles the IAT
sensor may be threaded into the intake air ducting
before the throttle body. On other vehicles it may
be threaded directly into the intake manifold after
the throttle body. After engine reaches operating
temperature, it may be difficult to verify IAT sensor
temperature when threaded into the intake mani-
fold. On vehicles where the IAT is threaded into the
intake air ducting, remove ducting to access IAT
sensor without disconnecting IAT sensor. Measure
air temperature around IAT sensor. Compare tem-
perature readings. If temperature readings are not
approximately the same, check for the following
before diagnosing:
n Contaminated or damaged IAT sensor,
connector or wiring.
n Damaged intake air ducting.
Catalytic Converter - Efficiency
An engine may run fine yet fail an emissions test.
The catalytic converter efficiency can be checked.

Start engine and test drive vehicle until normal
operating temperature of 85-105°C (190-220°F)
is reached and temperature stabilizes. On some
vehicles the catalytic converter temperatures will
lower and become insufficient for testing purposes
if the vehicle is left idling for a prolonged period of
time. For vehicles equipped with electric cooling
fans, ensure fans cycle on and off three times
prior to testing catalytic converter. During test, hold
throttle to keep engine running at 1000 RPM.
Fig. 6: Measuring Converter Inlet &
Outlet Temperatures
Using the IR thermometer, measure the inlet
and outlet temperatures of the converter. See
Fig. 6. Compare inlet temperature to outlet
temperature. On vehicles equipped with 2-way
catalytic converters, temperature differential will
be 55°C (100°F) or more. On vehicles equipped
with 3-way catalytic converters, temperature
differential will be 20°C (30°F) or more. The outlet
temperature will be hotter when the converter
is operating properly. If temperature differential
between converter inlet and outlet are less than
specified or the application, then the converter
needs to be inspected further. Before replacing
the catalytic converter, determine cause of failure.
Catalytic converters are designed to last the life
of the vehicle. If vehicle has high mileage of over
240,000 kilometers (150,000 miles) it is probably
just expired. If the vehicle has low mileage of less
240,000 kilometers (150,000 miles) then check
for the following:
n Ignition system malfunction (misfire).
n Fuel system malfunction (over-lean or
over- rich condition).
n Emission system operation
(O2, air injection, etc).