Disconnecting Carbon Cannister
Discussion
I've long since disconnected the pipework to my can and have the fuel tank vented to air through a breather near the diff, but now need to declutter some airspace at the front end and physically remove the can. Question is do I need to do anything with the wiring to the can or just disconnect ? Thanks in anticipation.
Richard 858 said:
I've long since disconnected the pipework to my can and have the fuel tank vented to air through a breather near the diff, but now need to declutter some airspace at the front end and physically remove the can. Question is do I need to do anything with the wiring to the can or just disconnect ? Thanks in anticipation.
You will need to plug the plenum .As the original vapour purge system is now redundant in the OP’s car it may be possible to ‘remove’ the corresponding code, which is a fair chunk, from the 14CUX firmware; but I don’t think anyone’s looked at doing this yet or the implications. Also I would remove the purge valve wiring from pin 17 (grey/yellow) at the ECU connector end and ensure the +12 V feed to the purge valve is well insulated, as it is spurred from the Fuel Pump relay/Inertia switch feed circuit.
In theory an Error code 88 Power Up Check will also be shown when using RoverGauge or ECUMate.
FWIW the following is gleaned from various LR docs and Dan Bourassa’s code comments:
Post ‘93 Griffith and Chimeras may have a fuel vapour control system that is controlled by the 14CUX ECU (via pin 17, a switched earth control for a purge solenoid valve). The system redirects vapours from the fuel tank to the plenum via a carbon filled canister so preventing harmful emissions into the atmosphere. The vapours are vented to the plenum chamber through a purge valve during engine operation. The ECU pulses the valve open for short periods below 1700 RPM and holds it fully open at higher speeds once the engine has achieved operating temperature and is in closed loop. Operating temperature is defined as engine coolant temperature above 54° C (130° F).
When the valve is opened the ECU monitors the need for further canister purge by analyzing lambda response. No change in lambda response with the valve open indicates that the canister has been fully purged and continued valve operation is curtailed.
Note: a disabled or faulty purge function can negatively impact vehicle emissions.
The 14CUX ECU uses one of its three timers and a dedicated interrupt to control the purge valve. There is a 16-bit value in memory (0x0096/97) that ranges between zero and 40,000 decimal. Driving conditions adjust this value. When the value is below 4000, the purge valve is OFF. When the value is above 29000, the purge valve is ON. When the value is between these two limits, the purge valve is pulsed ON for a period between 4 to 29 milliseconds.
In theory an Error code 88 Power Up Check will also be shown when using RoverGauge or ECUMate.
FWIW the following is gleaned from various LR docs and Dan Bourassa’s code comments:
Post ‘93 Griffith and Chimeras may have a fuel vapour control system that is controlled by the 14CUX ECU (via pin 17, a switched earth control for a purge solenoid valve). The system redirects vapours from the fuel tank to the plenum via a carbon filled canister so preventing harmful emissions into the atmosphere. The vapours are vented to the plenum chamber through a purge valve during engine operation. The ECU pulses the valve open for short periods below 1700 RPM and holds it fully open at higher speeds once the engine has achieved operating temperature and is in closed loop. Operating temperature is defined as engine coolant temperature above 54° C (130° F).
When the valve is opened the ECU monitors the need for further canister purge by analyzing lambda response. No change in lambda response with the valve open indicates that the canister has been fully purged and continued valve operation is curtailed.
Note: a disabled or faulty purge function can negatively impact vehicle emissions.
The 14CUX ECU uses one of its three timers and a dedicated interrupt to control the purge valve. There is a 16-bit value in memory (0x0096/97) that ranges between zero and 40,000 decimal. Driving conditions adjust this value. When the value is below 4000, the purge valve is OFF. When the value is above 29000, the purge valve is ON. When the value is between these two limits, the purge valve is pulsed ON for a period between 4 to 29 milliseconds.
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