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  #1  
Old 12-24-2008, 04:29 AM
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Purge Valve?

In the attached picture, is the device circled in yellow with MOT on the top the purge valve or "regeneration switchover valve" as the service cd calls it? On my '00 E320 you can here this device ticking and can feel it pulsating very easily. On the '94 I have never heard it or been able to feel it working. If it is what i think it is I know it deals with fuel vapor. What issues might I have if it doesn't work?

Thanks

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Purge Valve?-100_1970.jpg  
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'94 E320 with 272,000 miles. '92 500SEL 133,000 miles.
Mods to the '94: TomTom GPS in place of ash tray, Auto Dimming Mirror ,Memory seat, DEI 545T Auto lamps, DEI 530T Auto Up/Down Windows, DEI Remote Start, Motorola Bluetooth® Car Kit, Built in phone charger using factory phone wiring, RainTracker Rain sensing wiper, Keyless Entry, Ambient lighting of center storage compartment. Soon: factory heated seats, REST
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Old 12-24-2008, 05:46 AM
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Probably has to do with the evaporative emissions charcoal canister. Purging pulls air through it, sucking the gasoline vapors into the intake to be burned.

Just a guess, based on the shape (similar to others I've seen on other makes/models, and the name, but without ANY experience on modern MB cars.
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Old 12-24-2008, 11:26 AM
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If it does not work, the N/59 Module should detect an Emmissions fault and the CE will come on...they get full of gas dirt/ crap and can be cleaned w/WD-40 squirted into the suction port.
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Old 12-25-2008, 12:27 AM
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Quote:
Originally Posted by Arthur Dalton View Post
If it does not work, the N/59 Module should detect an Emmissions fault and the CE will come on...they get full of gas dirt/ crap and can be cleaned w/WD-40 squirted into the suction port.
I took it out and cleaned it with WD-40 as suggested. I also hooked to to 12+ volts while it was out and it did work but with not much force. Once it was back in I stated the engine and waited until all the required conditions were met for it to activate, it never did. I then put a LED on the pins and confirmed the ECM is commanding the purge valve. I checked the codes and got nothing. Then I pulled the suction line to the valve and the valve stating pulsing, again not with much force. I am theorizing that the vacuum from the engine is to much for this weak valve to overcome and it cannot open. Although the valve technically works it is to weak to preform its function in the evap system.

When the evap system isn't functioning what happens to the fuel vapor in the charcoal canister?
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'94 E320 with 272,000 miles. '92 500SEL 133,000 miles.
Mods to the '94: TomTom GPS in place of ash tray, Auto Dimming Mirror ,Memory seat, DEI 545T Auto lamps, DEI 530T Auto Up/Down Windows, DEI Remote Start, Motorola Bluetooth® Car Kit, Built in phone charger using factory phone wiring, RainTracker Rain sensing wiper, Keyless Entry, Ambient lighting of center storage compartment. Soon: factory heated seats, REST
Mercedes-Benz is my addiction of choice.
http://www.youtube.com/vanwiek
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  #5  
Old 12-25-2008, 12:32 AM
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It becomes saturated...


Purge code on that chassis would be 21 Blinks , but it will only throw that code if the valve is open/shorted/or no command signal...it does not monitor the actual vac flow of the valve.

Which is why you don't show a code.
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Old 12-25-2008, 12:55 AM
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Quote:
Originally Posted by Arthur Dalton View Post
It becomes saturated...
Should I replace the canister?

Quote:
Originally Posted by Arthur Dalton View Post
Purge code on that chassis would be 21 Blinks , but it will only throw that code if the valve is open/shorted/or no command signal...it does not monitor the actual vac flow of the valve.

Which is why you don't show a code.
Thanks, that's what I was thinking.
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'94 E320 with 272,000 miles. '92 500SEL 133,000 miles.
Mods to the '94: TomTom GPS in place of ash tray, Auto Dimming Mirror ,Memory seat, DEI 545T Auto lamps, DEI 530T Auto Up/Down Windows, DEI Remote Start, Motorola Bluetooth® Car Kit, Built in phone charger using factory phone wiring, RainTracker Rain sensing wiper, Keyless Entry, Ambient lighting of center storage compartment. Soon: factory heated seats, REST
Mercedes-Benz is my addiction of choice.
http://www.youtube.com/vanwiek
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  #7  
Old 12-25-2008, 04:36 AM
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If you can buy just the valve, I'd replace it alone, rather than the whole canister. With any luck the canister shouldn't be damaged by the fuel saturation, as it is designed to hold fuel.

If you don't mind a little scrounging, maybe hit a local wrecking yard and see if you can find one that way? You could even get the canister as well, if you felt like it.
That being said, who knows where they hid the canister on your vehicle. Some of the new ones have been putting it on top of the fuel tank, or in that general area, making it more and more of an adventure to find.
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  #8  
Old 12-25-2008, 04:52 AM
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Quote:
Originally Posted by hey_allen View Post
If you don't mind a little scrounging, maybe hit a local wrecking yard and see if you can find one that way? You could even get the canister as well, if you felt like it.
Actually, scrounging threw salvage yards is a favorite weekend activity. I plan on hitting some this weekend.

Quote:
Originally Posted by hey_allen View Post
That being said, who knows where they hid the canister on your vehicle.
I think mine is in one of the front fender well's, behind the plastic well liner. I'll have to check.

Thanks
__________________
'94 E320 with 272,000 miles. '92 500SEL 133,000 miles.
Mods to the '94: TomTom GPS in place of ash tray, Auto Dimming Mirror ,Memory seat, DEI 545T Auto lamps, DEI 530T Auto Up/Down Windows, DEI Remote Start, Motorola Bluetooth® Car Kit, Built in phone charger using factory phone wiring, RainTracker Rain sensing wiper, Keyless Entry, Ambient lighting of center storage compartment. Soon: factory heated seats, REST
Mercedes-Benz is my addiction of choice.
http://www.youtube.com/vanwiek
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  #9  
Old 12-25-2008, 11:18 AM
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A notation to respond to your vac reply:
Don't expect a full vac from the purge when it is demanded...they are pulsed for just that reason.
The freq from the ECU command is from 5-20 htz., depending on engine load criteria...they do this so there is not a large Gulp of air hitting the intake all at once, effecting a/f mixture controls.

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