Evap Leak Check - Toyota 2006 PRIUS Manual

4) EVAP Leak Check

a. General
The EVAP leak check operates in accordance with the following timing chart:
" A
Timing Chart
ON (Open)
Purge VSV
OFF (Close)
ON
Vent Valve
OFF (Vent)
ON
Leak Detection
Pump
OFF
Atmospheric Pressure
System
Pressure
0.02 in. Leak Pressure
Order Operation
Atmospheric Pressure
1)
Measurement
0.02 in. Leak Pressure
2)
Measurement
3) Vacuum Introduction
4) Purge VSV Monitor
Repeat 0.02 in. Leak
5)
Pressure Measurement
6) Final Check
NEW FEATURES - 1NZ-FXE ENGINE
1) 2)
ECM turns vent valve OFF (vent) and measures EVAP
control system pressure to memorize atmospheric pressure.
Leak detection pump creates negative pressure (vacuum)
through 0.02 in. orifice and pressure is measured. ECM
determines this as 0.02 in. leak pressure.
Leak detection pump creates negative pressure (vacuum)
in EVAP control system until the pressure stabilizing and
measures and memorizes the stabilizing pressure.
If EVAP control system pressure does not stabilize
within 15 minutes, ECM cancels EVAP monitor.
ECM opens purge VSV and measures EVAP control
system pressure increase. If increase is large, ECM
interprets this as normal.
Leak detection pump creates negative pressure (vacuum)
through 0.02 in. orifice and pressure is measured. ECM
determines this as 0.02 in. leak pressure.
ECM compares 0.02 in. leak pressure with pressure
memorized in vacuum introduction, and detects any
leakage.
ECM measures atmospheric pressure and records
monitor result.
3) 4) 5)
Description
23
NF
6)
275TU47
Time
10 sec.
60 sec.
Within
15 min.
10 sec.
60 sec.
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