EVAP Canister

WARNING: This page is about a different car, the 2003 Dodge Intrepid, 2003 Chrysler Intrepid, 2003 Chrysler Concorde, and 2003 Chrysler 300M. However, it is still accessible from the selected car via links, so may be relevant.

All vehicles use a maintenance free EVAP charcoal canister. See Fig 1 . Fuel tank vapors vent into the canister. The canister temporarily holds the fuel vapors until the intake manifold vacuum draws them into the combustion chamber. The Powertrain Control Module (PCM) purges the canister through the proportional purge solenoid. The PCM purges the canister at predetermined intervals and engine conditions. Purge-free memory cells are used to identify the fuel vapor content of the EVAP canister. Since the EVAP canister is not purged 100 percent of the time, the PCM stores information about the EVAP canister's vapor content in a memory cell.

The purge-free cells are constructed similar to certain purge-normal cells. The purge-free cells can be monitored by using the DRBIII(R) scan tool. The only difference between the purge-free cells and normal adaptive cells is that in purge-free, the purge is completely turned off. This gives the PCM the ability to compare purge and purge-free operation.

Fig 1: Locating Fuel System Components At Fuel Tank

Courtesy of DAIMLERCHRYSLER CORPORATION