0496

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nicotheman

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#1
I have an intermittent 0496 (high purge flow). My Actron tool measures both EVAP PURGE and EVAP VP but freezes only the PURGE value. I think if I had both, I could determine if the problem is the purge valve or the pressure sensor. Is there any way to capture VP? The code appears only once every 2 weeks.
 

kev2

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#2
what vehicle- year. make, model, eng, trans, color?

This is a P0496? that alpha character is needed when discussing codes. .

What is - purge value, evap VP? Purge is on or off - maybe knowing vehicle will help explain-
 
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nicotheman

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#3
Kia Rio. Yes, P0496. High purge flow should mean the fuel tank pressure drops (frequently at a vacuum), when the purge valve is commanded open (% commanded is indicated by EVAP PURGE). The PURGE VP is the pressure in the fuel tank. If the pressure is too low for the commanded position of the valve, the 0496 is triggered. The last data freeze showed 0% commanded, but I have no data on the vacuum level.
 

kev2

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#4
Check the purge valve- see if it is applying vacuum when commanded OFF - often we see the valves not seating "leaking vacuum" therefor the tank pressure would be lower than expected.

A KIA - still have no answers to the first response - what vehicle- year. make, model, eng, trans, color?
 
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nicotheman

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#5
It is a 2009 1.8L manual transmission. My problem is that it is intermittent, so I don't expect to see the condition during troubleshooting. When I observe the valve command and pressure while driving, the value seems to always correlate. My question has more do with using the Actron tool and not on how to test the purge valve. Do you know if there a way to determine the acceptable pressure values for each commanded position (are there table accessible from the Actron tool)? I am trying to avoid removing the valve, because it is difficult to pull off and it is 30F outside. If the Actron won't help, I'll pull the valve and clean it and then wait at least 2 weeks. If that doesn't work, I'll go to salvage and get a used purge and pressure valve when the weather breaks.
 

kev2

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#6
THe evap checks will not run every start/trip... All you questions for actron should go to them - they have a web site, manuals to down load and a help/tip page.

I went to do a check on the system - I only see a 1.6L engine...

Ideally - using a scanner we would command purge, close vent while observing the operation of the valve and monitoring the FT pressure sensor readings change. OR jump ahead to a smoke test with eng to valve vac line off
 
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nicotheman

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#7
OK, thanks. I wish my tool would send commands, but I am not willing to pay more than $200 for one that does.
 
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#8
When the purge valve opens, draws a vacuum from the thank, pressure voltage should go up a volt or so. If that vacuum does not go up 99% of the people blame the gas cap. But the vent valve must be closes, it sucks air in both in and out and get loose carbon from the canister to get plugged up causing this leak. Normally can be cleaned with denatured alcohol, and can be tested with a hand vacuum pump.

Other causes can be minor leaks in the filler tube, with a long ride to the fuel tank, many possibilities here. With all these connectors at the bottom of the vehicle, they are exposed to road salt and debris, can also be a dirty connector.

Where is your canister and vent valve located? Use to be high under the hood, where they presented very little problems. Some idiot decided to mount them back at the fuel tank where they are exposed to all kinds of crap.