Need to vent AZ emissions

azsprint6 · #1 (**permalink**) 01-31-2012, 01:27 PM

Have a code po446 on a GMC Sierra -evap vent system problem as per dealer did the vent solenoid update then the canister and purge valve. Spent enough to get a waiver (Do not want that) but could not get one without a fail paper. Well it will fail with the check engine light on. After repairs and clearing the code and driving 90+ miles monitor readiness still not ready, then bam on comes the light again, same code. I think without emmision testing there would be much less pollutants in the air. Just think about how many cars sit and idle at the test stations and the crap we go through to get ready for retest. Then think about drive through everything, Shut off the car and get off your fat ass and walk into the place. So sorry to vent but if you can help with the code I'll shut up Dan HM1011

oleyellar · #2 (**permalink**) 01-31-2012, 04:18 PM

Have you replaced the gas cap??.... That is the problem most of the time.... They make it way more complicated than it needs to be.
It's a cheap, and quick test.
good luck.

MT nester · #3 (**permalink**) 02-01-2012, 03:38 AM

Put some wheel bearing grease on the gas cap O ring.

azsprint6 · #4 (**permalink**) 02-01-2012, 06:01 AM

The gas cap was the first thing replaced, Sorry I did'nt mention that Dan

vettestr · #5 (**permalink**) 02-01-2012, 09:18 AM

take a look at this page. P0446 Evaporative Emission Control System Incorrect Purge Flow

it has a solenoid that is most often the cause if cap is good. It has 4 sections to total system and start at canister and verify compliance of each until you find the fault.
PS a few shops that specialize on emissions and cheaper that the dlr for sure.

azsprint6 · #6 (**permalink**) 02-01-2012, 01:20 PM

Heres the problem, I thought I was the emmisions expert. After 38 years of this car repair crap this one is KICKIN me. Should be so simple but not this one. Now taking the gas tank out to replace the evap pressure sensor that comes with the fuel pump. Man I hate throwing parts at this but it has to be done. Maybe after repairs will have to dealer flash the PCM and give it a new brain. I am so lost on this one hurts my head.
Just to refresh whats been done is gas cap, evap vent update, purge valve and canister, now will be the tank pressure sensor, Have no good feelings about that result either. Everytime I look at this truck more hair shoots out of my head.

LMH · #7 (**permalink**) 02-01-2012, 06:40 PM

Hang in there Dan!
Larry

vettestr · #8 (**permalink**) 02-01-2012, 09:08 PM

Dan, I didn't pick up on the fact this one has haunted you so far. I know the feelings all to well from my own collection of haunted houses.

Are you thinking the solenoid is hung open or leaking -- can you bypass or trick system to think it seals properly by plugging vent hose? What if it would pass the tests and not throw a code with hose blocked and prove fault before replacement? Just a shot in the dark. Jeff C