Chrysler Repair: 94 3.0L engine: Stalling when slowing, wd 40, purge valve

Question
Hi Roland,

We had chatted a few weeks ago about on overheating Lebaron, with the thought that the thermostat was inserted improperly.  As a follow up, the thermostat was not the problem ... turns out, the radiator was falling apart inside, and the water pump was bad (it started to make a noise that sounded like a diesel, and it started leaking all over the driveway).  Anyway, new radiator, new timing belt, new pump, and presto ... car runs great.  I have a question, though, about the vapor cannister pure solenoid.  The one in my car makes a ticking noise, like a tapping valve, and I was wondering (a) what this valve does, and (b), should it be ticking?  Historically, every now and then, when I pull up to a traffic light with this car, the engine drops to 700-800 rpms, before settling at a higher idle (almost like it's going to stall, but it never does).  Is this possibly due to a bad Vapor cannister Purge solenoid?

Thanks again for all of your continued help.

Andy

Answer
Hi Andy,
The near-stall when slowing/stopping is more likely due to the egr valve. You will see the valve mounted in a small pipe that branches off the front exhaust manifold and crosses over toward the rear of the vehicle. It has round vacuum actuator on its top, and flange in between that and the valve body mounted in the pipe. Look inside the flange to see a rod which is the valve stem. The stem has a slot into which the tip of a screwdriver can be inserted and used to move the stem back and forth, against spring-action in one direction that is trying to close the valve. That action should close to a dead stop. If it appears to be sticking then stray some WD-40 on the stem where it enters the valve body and work the stem some more. Then see if that helps eliminate the problem. If not. then you may want to remove the valve and clean out the internal passageway. That valve has to close tightly at idle or it will lean out the mixture excessively.
The purge valve operation you described is typical. It may just be a bit noisy or loose in its mounting. It operates after the engine is warmed up and the tapping is oscillation controlled by the pcm to meter vapor from the canister into the engine after it has warmed up. So I doubt that explains the near stall.