P0446, ready for smoke test

02, 3.4 auto, 4WD. Occasional P0446. Just tired of seeing it and turning it off.

Got an adapter for evap test port and attempted to smoke test it. The way I had the air supply rigged up I had to puff some in, go look, puff more in , , ,

So, that did not go too well, so dropped back to re rig the air supply. Shop compressor, couple valves to supply and bleed off as the regulator does not go low enough. Anyway.

Once I get a constant supply of smoke, I get from the diagrams that in a engine off state, smoke should go back to the cannister and I should be able to see any leaks. Correct? Would it eventually fill the cannister and the fuel tank, etc?

I also gather it is likely to be the tank pressure sensor, or maybe the grommet, for this code? Expensive sensor.

Expensive as some of this stuff is, I do not want to take a shotgun approach.

I have a tester that says "evap system test", but no data on what it actually does. Any ideas on that?

This truck did have a frame replacement, new gas tank and filler a couple years back.

 

I just attempted to do this on my truck two weeks ago, but it was for a "small evap leak" code, let me get on my computer and find the part of the FSM that I referenced...you have the 3.4L so this will be a lot easier since the charcoal canister isn't on top of the gas tank.

Edit:
I had the same code about 3 years ago. There is a solenoid on the canister itself (at least on the 2.7L) that is not replaceable and fails since it's under the bed and exposed to salt etc.. You should test all of these solenoids too (there's 3 on the 2.7L), I have a hunch its the one on the evap canister..

 

Judging by your informed approach, I believe it's safe to say it's not something as simple as a loose or faulty gas cap. That being said, I do faintly remember putting a canister and possibly a valve or two in my father's 04 like 4 or 5 years ago, so I wouldn't rule that out on the basis of being the part that never fails.

 

On my 3.4 the canister is under the bed.

 

I was getting more codes last year. All evap related.

Changed the gas cap and only the P0446 keeps coming back. Mostly when near half empty. Never saw the others again.

I did a quick survey of connections. All the ones with clips or clamps seemed tight. There were one or two that looked simply "push on" and they did rotate a bit if I tried hard.

 

My bad...I believe it's the 4runners that are different. I would put money on it being that solenoid on the canister then if it's under the bed. Test the two in the engine bay first though. P0446 might not be a leak, I think you'd get some more evap leak codes in addition to the P0446. So the smoke test might not be that helpful right now. I attached the troubleshooting PDF from the FSM for P0446

This screenshot might also be helpful for you:

 

For more reference...here are the sections that tell you how to test each solenoid. Just apply/remove voltage and blow through it, it's super easy...except the one under the bed.

The pdf called "insp(2)" is the one for the solenoid on the canister under the bed.

 

P0446 is usually the Purge Selnoid.
If it leaks even slightly it will throw the code. Best to test it with vac pump and gauge. Mine passed the blow test but did not seal intermittently.
Also @joea99 you have to clamp off the cannister air drain hose when smoke testing.

 

Thanks for all the hints. I can add that I have never, ever, noticed any pressure in the fuel tank when cracking the gas cap to fill up. Or, if there was pressure, it was so slight I could not tell. I guess that should mean something.

Oh, and I guess, if it is that solenoid you mention, it is one I cannot get by itself?

 

If it’s the one on the charcoal canister, no I was unable to find one a couple years ago. Unless maybe you could find someone on here parting out their truck and willing to sell you just the solenoid. I just bought a whole new canister from RockAuto for like $200

Your best bet for inspecting and replacing the charcoal canister is taking the bed off or dropping the tank. I prefer taking the bed off cause you can work on it from the top. It’s a two person job though.

 

Your tester for EVAP wont work because your Taco does not have an EVAP pump. You will need a hand pump and gauge. The Purge Selnoid should be next to the EVAP port on right fender well top under hood.
You wouldn't get pressure at gas cap right after engine shut off to fill up.
And you wouldn't get pressure if the Purge Selnoid or gas cap leaked after being parked in sun.
Wouldn't get pressure if any leaks at all were present for that matter.

 

That one I tested last spring, just using the "Blow through" test and jumper wires.

 

The one that crosses to my p/n is out of stock on Rock Auto. I was considering taking the bed off to fix a rust spot in the corner by the passenger door. Guess I have to break down and do it.

 

Yeah, mine passed the blow test but failed to hold pressure while using hand pump and gauge.
P0446 as the only code does not indicate a leak but that the computer is unable to run an EVAP test due to circuits or valves. That's why you have to test both wires with a multimeter and valves with air. A hand vac/pressure pump is real helpful when testing EVAP. More modern Tacomas have an EVAP pump which makes diagnostics easier.

 

I have a hand vacuum pump for brake bleeding I suppose I could use. What sort of pressure/vacuum? There is a warning tag on the evap test port about max pressure, so ?

 

You'll need a pump with gauge to check for pressure drop. Measured in inches of vacuum/pressure.
We aren't talking lbs pressure like from an air compressor.
I think the green tag on port indicates Max 2"
You had me cringing by mentioning smoke testing with compressor.

 

@joea99 you still have the original 20 year old vac lines?
There is a company that sells a thick wall silicone vac line set for 3.4L
$29 shipped IIRC.

 

@joea99
https://parts.olathetoyota.com/p0446-code-toyota

 

looks like it’s in stock...the last one on the list that’s out of stock is one that goes in the engine bay not under the bed.

 

I found the Purge Senoid on Amazon
$89

May also be available on link below
As well as cannister VSV if it's also Denso
https://densoautoparts.com/find-my-part.aspx