Lotus 2004 ELISE Service Notes page 273

Lotus Service Notes
The third, 'purge' port, controlled by a solenoid valve mounted on the inlet manifold, connects the underside
of the charcoal bed with a port on the engine intake plenum. The pulse width modulated vapour management
valve is opened during certain engine running conditions in order to allow intake depression to draw fresh air
through the vent pipe and charcoal bed, cleansing the charcoal of fuel before consuming the resultant vapour
in the normal combustion process. In this way, the charcoal is prepared for further vapour absorption.
Control System
The vapour manageement valve is controlled by the engine management ECU, which keeps the valve
closed (unenergised) when the engine is cold or idling in order to maintain idle quality. At normal running tem-
peratures and engine speeds above idle, the ECU monitors other running conditions and the status of various
management systems, and when appropriate conditions pertain, the ECU will apply a duty cycle to the valve in
order to regulate the amount of purging allowed dependent on the amount of vapour in the canister.
LK.7 - FUEL TANK PRESSURE TEST
In order to verify the sealing integrity of the fuel tank and filler system, the following test should be per-
formed:
1. Use the Lotus Scan tool to close the canister vent valve or apply 12 volts and ground to the two terminals
of the vent valve electrical connector.
2. Locate the test port in the purge line between the canister and vapour management valve (VMV), which is
itself mounted on an inlet manifold plenum bracket, and connect an appropriate tester or pressure pump
and water manometer as shown in the diagram.
Pressure pump
with gauge
To intake plenum
3. Pressurise the tank to 20"H
4. Allow to stabilise for 30 to 60 seconds then take a reference point and start measuring the pressure decay
over a period of 60 seconds.
Typical pressure reduction over this period should not exceed the region of 1" H
Pressure loss of between 2" H
a trouble code (P0456 - minor pressure loss) to be set. Minor leaks equivalent to a 0.5 mm (0.020 inch)
hole, may be caused by:
- Inadequate sealing of the VMV. To verify, clamp off the flexible hose between the VMV and inlet
manifold and repeat the test. A significant improvement indicates a suspect valve. Clean or renew.
sn_lk_croft.indd 11
Test
port
O (5.0 kPa).
2
O (0.5 kPa) and 3" H O (0.75 kPa) will cause the MIL to be illuminated and
2 2
Section LK
Vapour Management Valve
O (0.25 kPa).
2
Charcoal
canister
L65
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