Outline Of Diagnosis

This diagnosis judges whether the Evaporative Leak Check Module Operation is normal or not, whether the sealing valve operation is normal or not, and whether the evaporative emission system has leak or not.

To purge the canister, after driving, perform the five hours soaking after ignition switch OFF in order to stabilize the evaporative gas status.

* After 5 or 7 or 9.5 hours passed, ECM is activated by soaking timer, and the leak check is started. First, judges whether the Evaporative Leak Check Module operation is normal or not, by measuring the reference pressure status via reference orifice (0.02 inch orifice).

Judge as malfunction if the reference pressure is out of specified range.

Then, judge whether there is a leak or not, by measuring Evaporative Leak Check Module pressure (canister side leak pressure) when the evaporative emission system becomes the negative pressure with the sealing valve closed and comparing with the reference pressure.

Judge as system leak in the evaporative emission system except for the fuel tank if the canister side leak pressure is higher than reference pressure.

At the same time, check whether the sealing valve operation is normal or not.

Judge as sealing valve open stuck if the amount of change of fuel tank pressure is equal to or larger than the specified value.

Then, judge whether there is a leak or not, by measuring fuel tank pressure (tank side leak pressure) when the evaporative emission system becomes the negative pressure with the sealing valve open and comparing with the reference pressure.

Judge as leak in the fuel tank or fuel cap, etc. if the tank side leak pressure is higher than reference pressure.

At the same time, check whether the sealing valve operation is normal or not.

Judge as sealing valve close stuck if the amount of change of fuel tank pressure is equal to or smaller than the amount of change of Evaporative Leak Check Module pressure.

0.02 inch leak and 0.04 inch leak can be distinguished by measuring the Evaporative Leak Check Module pressure and fuel tank pressure.

Also, it is possible to determine if leak is from the fuel tank or other locations.

The diagnosis results are stored inside ECM until the engine is started again.

*: When the test conditions are not met in 5 hours, perform diagnosis at elapsed time of 7 hours. When the test conditions are not met in 7 hours, perform diagnosis at elapsed time of 9.5 hours.