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Discussion Starter · #1 ·
So I think I’m fundamentally missing something with the evap system in my 06. It seems like the evap purge solenoid on the engine is constantly open when the engine is running. I was under the impression that the solenoid only opens when it is venting the tank and not during constant operation? Or am I misunderstanding it’s purpose? I know there are 2 solenoids, one on the engine and one in the back of the car.
 

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Engine one should be closed unless the motor is running and pulling vacuum on it. Im sure pressure can open it to. But the rear one is meant for that and allowing the fresh air in the tank.
 

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So I think I’m fundamentally missing something with the evap system in my 06. It seems like the evap purge solenoid on the engine is constantly open when the engine is running. I was under the impression that the solenoid only opens when it is venting the tank and not during constant operation? Or am I misunderstanding it’s purpose? I know there are 2 solenoids, one on the engine and one in the back of the car.
it vents the vapors from the canister and lets the engine munch on them. if you think it's stuck open, just try replacing it.
 

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I had a small evap leak for years. It would go away in the hot summer when I would get it inspected and come back in the winter. I thought it was evap cannister by the gas tank, but it turned out to be the purge solenoid under the hood.

It's no good having a check engine light for something small like that and not taking care of it because it would mask any other CEL you might get that could cause bigger problems if left unchecked.
 

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Discussion Starter · #9 ·
So just to be clear, if the engine is running then it's normal for the engine evap solenoid to be open? In a semi-similar vein I'm all too familiar with the rear evap solenoid as I just had to replace it to get my 06 to fill normally at the pump again.

I had a small evap leak for years. It would go away in the hot summer when I would get it inspected and come back in the winter. I thought it was evap cannister by the gas tank, but it turned out to be the purge solenoid under the hood.

It's no good having a check engine light for something small like that and not taking care of it because it would mask any other CEL you might get that could cause bigger problems if left unchecked.
I have the added luxuries of having lived in a state that doesn't do emissions up until about a month ago and not doing my own tuning. So it seems like any CEL related to evap or vacuum leaks is turned off in my car and trying to get the emissions junk reinstalled and working again has been extra fun.
 

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So just to be clear, if the engine is running then it's normal for the engine evap solenoid to be open? In a semi-similar vein I'm all too familiar with the rear evap solenoid as I just had to replace it to get my 06 to fill normally at the pump again.
vacuum opens it, so yes, running the engine would open it. I doubt it has anything to do with you having issues putting gas in the tank.
That would be the purge valve and charcoal canister
 

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Discussion Starter · #11 ·
vacuum opens it, so yes, running the engine would open it. I doubt it has anything to do with you having issues putting gas in the tank.
That would be the purge valve and charcoal canister
Not overly familiar with all the terminology but the rear vent solenoid assembly I replaced recently and that fixed the filling issue.
 

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Well it doesnt have any moving parts the ecu can control, so wont matter what it commands. Which is the sensor I'm referring to when they state on the engine.
i don't think we're talking about the same part.

OP was asking about the evap purge solenoid.

the only sensors i can think of that respond to vacuum are the MAP and the fuel tank pressure sensor.
 

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Discussion Starter · #18 ·
Well he said the one on the engine, so that's all im referring to as they said they replaced everything else.
The EVAP purge solenoid on the engine is an electrically activated solenoid commanded open by the computer. I've tested it with the line disconnected that unplugging the electrical connector for it will cause it to close with the engine running.
 

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The EVAP purge solenoid on the engine is an electrically activated solenoid commanded open by the computer. I've tested it with the line disconnected that unplugging the electrical connector for it will cause it to close with the engine running.
Which would mean it cant command it closed and throw a cell if it doesnt respond.
 

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it certianly can command it closed, by sending no signal to it. it can also throw a code for it.

the ECM can tell what's going on with the evap system and can set a code when it runs the evap system tests, when the fuel tank pressure sensor reading isn't what is expected.

so if it runs a test where it has commanded the purge solenoid closed and vent solenoid open, and if tank vacuum builds, then something is up.

inversely, there is a test where the purge solenoid is commanded open, and the vent solenoid closed. in this case tank vacuum should build. if it does not, something is up.

it's all in the service manual description that i posted above.

it is possible that an intermiddant failure can happen while a test is not being performed. in that case, a code wouldn't be thrown for the evap.
 
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