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P0446 Small EVAP Leak

  #1  
Old 07-09-2019, 08:29 PM
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Default P0446 Small EVAP Leak

Trying to do a bit of last minute troubleshooting on an ill timed P0446 Small Leak code/MIL before a 4X4 trail camping trip. I don't notice any driveability issues. I have looked over the gas cap seal and it looks good. I put together one of those DIY pickle jar smokers and after finding out the schrader valve needs a slightly larger sized core remover tool, I got it out and on the hose on the test port. With the gas cap off, I only let the pump handle slowly go down to keep pressure down and after no more than one pump there was enough pressure to get the smoke to back up and out the jar/soldering iron handle. I used car gauge and tried every combination of opening and closing the vent and purge valve with the same result. I can hear the charcoal canister valve definitely click/open and close, whereas the purge valve seems to make a repeated light sounding clicking for about 15 seconds along with what I can only describe as a gurgle noise I can only hear at the end of the 15 seconds when the clicking stops.
I haven't been able to test the voltages at these solenoids yet..with that being said I am assuming the purge solenoid is not fully opening, causing the leak, but still functioning enough for it to not throw its own specific MIL code?
I am leaving for the trail/camping Thursday morning, and am going to pickup a new purge valve just because that is my best guess right now and would like to have it with me to swap if it goes bad.. hopefully not stranding me in the deep woods.

Why would I not be able to get smoke to the tank and out the cap with both of these solenoid open/closed other than one not functioning.. Any other last minute ideas?
Thank you
 
  #2  
Old 07-10-2019, 10:56 AM
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Originally Posted by Doubledown View Post
Trying to do a bit of last minute troubleshooting on an ill timed P0446 Small Leak code/MIL before a 4X4 trail camping trip. I don't notice any driveability issues. I have looked over the gas cap seal and it looks good. I put together one of those DIY pickle jar smokers and after finding out the schrader valve needs a slightly larger sized core remover tool, I got it out and on the hose on the test port. With the gas cap off, I only let the pump handle slowly go down to keep pressure down and after no more than one pump there was enough pressure to get the smoke to back up and out the jar/soldering iron handle. I used car gauge and tried every combination of opening and closing the vent and purge valve with the same result. I can hear the charcoal canister valve definitely click/open and close, whereas the purge valve seems to make a repeated light sounding clicking for about 15 seconds along with what I can only describe as a gurgle noise I can only hear at the end of the 15 seconds when the clicking stops.
I haven't been able to test the voltages at these solenoids yet..with that being said I am assuming the purge solenoid is not fully opening, causing the leak, but still functioning enough for it to not throw its own specific MIL code?
I am leaving for the trail/camping Thursday morning, and am going to pickup a new purge valve just because that is my best guess right now and would like to have it with me to swap if it goes bad.. hopefully not stranding me in the deep woods.

Why would I not be able to get smoke to the tank and out the cap with both of these solenoid open/closed other than one not functioning.. Any other last minute ideas?
Thank you
P0446 is not the small leak code. That is P0442.

Plugged charcoal cannister or plugged line or bad vent valve probably? I read about issues with dust/dirt plugging these up and my Avalanche actually had a plugged charcoal cannister that set a P0446.

Not really understanding exactly how you are testing, but I sure wouldn't worry about a P0446 causing any driveability problems during your trip. Worst case is slow filling at the gas pump if tank doesn't vent when the key is turned off. Have a good trip.
 

Last edited by LesMyer; 07-10-2019 at 11:06 AM.
  #3  
Old 07-17-2019, 05:21 PM
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Originally Posted by LesMyer View Post
P0446 is not the small leak code. That is P0442.

Plugged charcoal cannister or plugged line or bad vent valve probably? I read about issues with dust/dirt plugging these up and my Avalanche actually had a plugged charcoal cannister that set a P0446.

Not really understanding exactly how you are testing, but I sure wouldn't worry about a P0446 causing any driveability problems during your trip. Worst case is slow filling at the gas pump if tank doesn't vent when the key is turned off. Have a good trip.
That code was from memory so I could have been wrong, and since the 2nd clearing it hasn't returned nor is pending. Maybe cycling all the solenoids resealed something.

I was opening the EVAP test port and pumping in low pressure smoke to see if I could see it escaping the gas cap or any hoses, or fittings etc. I was opening both the solenoids to make sure the smoke was reaching/filling the entire system but I could never fill the tank and have it come out the gas cap when i had it purposefully open.

Trip went well, few most brush scratches and nothing broke and as i mentioned the code has not returned. Whole trip reminded me I need to definitely identify the odd exhaust leak/rocker noise and still put in my upgraded spider injection system.
As always thanks Les
 
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