Dodge Durango Forum II

Re: OT: Air leak?

Might be the Canister Purge Solenoid. It is located right next to the brake booster and by the way, it's a good candidate as well. Sometimes the check valve fails on the BB or cracked hoses can cause this. The key to the repair is that you are noticing a great deal of vacuum hiss after shutdown. That tells me it's gotta be leaking from a vacuum reservoir of some kind. Biggest on the driver's side is Brake booster, which will hold vacuum inside by the check valve that is inserted on the left side. Biggest on passenger side is the cruise control vacuum reservoir, located under the cowl. But a stuck valve may cause the Canister Purge to exhibit the same symptoms. I had a vacuum leak by a cracked PCV hose @ the manifold, but it tripped my engine light (and this was at 15K miles too). Most vac leaks are not noticeable on shutdown, so something that is supposed to hold vacuum is not. I like the hose in the ear idea. An old stethoscope works well too... just pull off the end.

From the Manual...
Description and Operation of Canister Purge Solenoid:

The duty cycle EVAP canister purge solenoid (DCP) regulates the rate of vapor flow from the EVAP canister to the intake manifold. The Powertrain Control Module (PCM) operates the solenoid.

During the cold start warm-up period and the hot start time delay, the PCM does not energize the solenoid. When de-energized, no vapors are purged. The PCM de-energizes the solenoid during open loop operation.

The engine enters closed loop operation after it reaches a specified temperature and the time delay ends. During closed loop operation, the PCM cycles (energizes and de-energizes) the solenoid 5 or 10 times per second, depending upon operating conditions. The PCM varies the vapor flow rate by changing solenoid pulse width. Pulse width is the amount of time that the solenoid is energized. The PCM adjusts solenoid pulse width based on engine operating condition.

CPS

Fri Jul 30