Is there a way to test the integrity and function ability of an EVAP Canister Control Valve (in engine bay area)?

I have been getting a gas vapor pressure leak warning. I have replaced all seals and hoses at the EVAP Flange. I was getting a slight gas vapor smell in the cabin when the windows or sunroof were open but that has stopped.

Still getting the warning after about 15 miles of driving but not always.

All under hoses, lines, canisters, connections are tight. New gas cap.

I was looking at the EVAP CCV this morning. For those unfamiliar:



I checked hoses around this valve and the valve body itself for vacuum leaks. I could not find any.

I took the cap off by carefully lifting up on the cap at the locking rim edge by hand as I rotated the cap. It took about 5 of the locking tabs to disengage before it came off easily.

Here is that image:



I cleaned the exposed parts with electrical cleaner spray and dried with a blow drier.

I tested the unit by cranking the car and putting my finger over the vacuum tube orifice. Strong vacuum but I suspect a leak or hole in diaphram as I can hear a whistle when I cover the tube. I could find no external leaks. Voltage at the pigtail is always 13.4v.

Listen carefully and you will hear the whistle:


Being the curious type I am wondering if anyone has tested one of these units.

Can someone tell me what this valve actually does?

Is there supposed to be vacuum at the orifice at all times?

What is the purpose of the green capped valve on mine that is not in repair manual?

Thanks!

 

What was the green cap covering???

 

I don't fancy testing mine to find out! Would the diaphragm have a little vent hole in case of a total block, so as not to destroy itself?
The connectors look dusty did you clean both parts and reseat them a few times?

'After a fuel system tweak like cleaning any parts it's good practice to carry out a hard reset to get back to Base setting on ECU and throttle maps, but to load them the car needs to run through a cycle without interruption - initial startup idle runs high then low to almost stall as the throttle sorts itself, then 10 minutes of idle to store maps.'

Then go from there...

I think I'll use the above as my new sig, lol!

Hope that helps

 

Hi Robert,

I can't answer all of your questions but I can answer a few. That valve is the Carbon Canister Purge Valve. The Evaporative Emissions system stores fuel vapors from the fuel tank in one or two canisters filled with activated charcoal. Under certain engine operating conditions (which I can't recall off the top of my head), the purge valve is opened to allow the stored fuel vapors to be inhaled into the intake manifold and burned in the engine.


I don't know about the integrity, if by that word you mean testing for vapor leaks to the outside air, but you should be able to test the function of the valve itself. I haven't tested one on an X308, but on most vehicles the default or unpowered state of the valve is closed, so it should not pass air between the two hose fittings when blown through. When 12V is applied to the electrical connector, the valve should open and allow air to pass.


There should be two hose fittings. One hose communicates with the carbon canister(s) and would probably not normally be under vacuum. The other hose communicates with the intake manifold, and may normally be under engine vacuum when the engine is running.

According to the Electronic Parts Catalog (which you can download from this forum), your U.S. car should have two carbon canisters, and there should also be a Canister Close Valve in the system, and a filter of some kind that appears to fit on the end of one larger hose which may connect to the Canister Close Valve. The parts diagram at jaguarclassicparts.com shows only the single-canister system.

Cheers,

Don