Impco HHI, Руководство по обслуживанию

Страница: 25 / 485

25
The Heat Exhaust Gas Oxygen (HEGO) Sensor
HEGO1 (upstream or before the catalytic con-
verter) and HEGO2 (downstream) voltage
output.
The Heated Exhaust Gas Oxygen Sensor
(HEGO) is an emissions control compo-
nent. In the event of a failure, the HEGO
should only be replaced with the recom-
mended OEM replacement part. The
HEGO is sensitive to silicone based prod-
ucts and can become contaminated.
Avoid using silicone sealers or air or fuel
hoses treated with a silicone based lubri-
cant.
TMAP SENSOR
T–MAP Sensor
The Air Temperature/Manifold Absolute Pressure
or TMAP sensor is a combination of two sensors:
1) A variable resistor used to monitor the differ-
ence in pressure between the intake manifold
and outside or atmospheric pressure. The
ECM monitors the resistance of the sensor to
determine engine load (the vacuum drops
when the engine is under load or at wide
open throttle). When the engine is under load,
the computer may alter the fuel mixture to im-
prove performance and emissions.
2) The intake air temperature or IAT sensor is a
variable resistance thermistor located in the air
intake passage which measures the tempera-
ture of the incoming air. The ECM uses the
resistance value to monitor incoming air tem-
perature and calculate the engine’s airflow
requirement. The ECM provides a voltage di-
vider circuit so that when the air is cool, the
signal reads a higher voltage, and lower when
warm. On cold starts, the ECM richens the
fuel/air mixture.
COOLANT TEMPERATURE SENSOR
ECT
The Engine Coolant Temperature sensor or ECT
is a variable resistance thermistor that changes
resistance as the engine's coolant temperature