2000 Silverado 5.3 Evap Valve Upgrade?

JackalAR · April 1, 2010

Got the P0446 SES about 2 months ago, so I removed the original valve and cleaned it out...was nasty. Also blew a LOT of powder fine dust out of the line, removed and cleaned the charcoal canister, etc. The SES went away until this AM. Another P0446. I removed and cleaned the purge valve which seemed clean for the most part. I went and got the newest vent valve (p/n: 25932571) and it's a LOT larger. It's suppose to go in the new location with the relocation kit, but I figured I could relocate it to the outside of the frame rail.

Questions:

Do the old and new style vent valves have the same electrical connector or will I need an adapter? Is the diameter of the hose connector the same diameter and style, or will I have to rig something up with heater hose and clamps? Details please...thanks!!!

JackalAR · April 20, 2010

Well the new valve BARELY fits and you have to heavily modify the old bracket, but everything plugs in alright. I hadn't had an SES since I replaced the valve till this AM. Same P0446 code. Now what? I'm thinking about ordering a purge valve and canister, but they aren't cheap. I hate to keep throwing money at this when I'm not sure if it's even going to fix it, and it drives fine as is. Might just have to accept the fact that Chevy trucks just have a persistent SES feature. Thanks for all the help by the way.

nickvrebel · April 20, 2010

how bad to you want the EVAP to actually work? Do you just want the light to go away? is so get a custom tune and have the tuner turn the code off ;)

JackalAR · April 20, 2010

I was just discussing that as an option with my co-workers, but figured I'd have a hard time finding someone to do it, and don't want to pay my local guy for dyno tuning again...not on this truck anyway. Any ideas on who would do this and how much?

cujo8 · April 20, 2010

I just went thru this with my 2006 Sierra and it turned out to be the gas cap seal was leaking. I also had the Evap Valve upgrade done as well even though it was not leaking yet (according to the smoke test), just because it is a known problem with these trucks. I was told you could test if the cap was the problem, by putting some petrolium jelly on the gas cap o-ring and see if the problem goes away. Hope this helps.

JackalAR · April 20, 2010

Thanks man!!! I am picking up the purge valve and gas cap today to try those first. The purge valve is $20 and gas cap $15 for GM genuine parts. I have thoroughly cleaned & inspected my gas cap and seal, and it appears to be fine and making a good seal. Compared to a co-worker's 03 with 3x the mileage it's like new, but for the price I can't see not trying it.

nickvrebel · April 20, 2010

yeah, if it's a cheap fix by all means do it the right way. To "fix" it in the tune is very simple, if you already have a tune your tuner shouldn't have a problem making this quick update for no charge or a 12 pack of beer. If you were local to me I could get it done for you.

JackalAR · April 20, 2010

Problem is this truck is relatively stock. My F150 has all the go-fast parts and gets all the attention. I don't know squat about tuning Chevys. I don't mind paying for premium fuel, but don't want to drop a lot of cash into yet another money pit.

Badshot · April 20, 2010

Problem is this truck is relatively stock. My F150 has all the go-fast parts and gets all the attention. I don't know squat about tuning Chevys. I don't mind paying for premium fuel, but don't want to drop a lot of cash into yet another money pit.

Ouch! to me seems like u droped all the fast parts into the ford was ur first mistake, Seeing lots of tests, i believe the chevy's have faster stock times then the ford anyday! oh well. Not trying to bash ya, and yea i get a p0449 code on mine, Any ideas on what it could be -_- or a cheap fix rather then buying a new silenoid for $200

JackalAR · April 20, 2010

First of all the p0449 code is an emissions related leak rather than a restriction is it not? This would make me think gas cap first. (Which actual code were you getting cujo?) Second the updated vent valve is only about $30, not $200. Last, I am a Ford man...I just inherited this one and intend to take care of it until my son is old enough to drive it. Neither truck has been to the strip, nor are they likely to ever. Stock this truck had 50 more HP than my F-150 did, but not only was GM not an option, I also had to have a 5-speed. Also, the 281 STILL had nearly the torque of the larger 327. They are basically the same trim otherwise, except I got all 4 doors and about 6" additional height. ;) Oh yea, my door hinges are also as solid as the day I got it where as the Chevy's doors are about to fall off with half the mileage. ;)

cujo8 · April 20, 2010

First of all the p0449 code is an emissions related leak rather than a restriction is it not? This would make me think gas cap first. (Which actual code were you getting cujo?) Second the updated vent valve is only about $30, not $200. Last, I am a Ford man...I just inherited this one and intend to take care of it until my son is old enough to drive it. Neither truck has been to the strip, nor are they likely to ever. Stock this truck had 50 more HP than my F-150 did, but not only was GM not an option, I also had to have a 5-speed. Also, the 281 STILL had nearly the torque of the larger 327. They are basically the same trim otherwise, except I got all 4 doors and about 6" additional height. ;) Oh yea, my door hinges are also as solid as the day I got it where as the Chevy's doors are about to fall off with half the mileage. ;)

The code I was getting was P0455 (Evaporative System Leak) and my DIC had the message "Tighten Gas Cap". My gas cap looked almost brand new, but I'm guessing the o-ring was dried out and was the source of the leak. The tech also replaced the Evaporative Vent Valve on the same invoice and again posted the same P0455 code. Hope this helps.

Badshot · April 20, 2010

First of all the p0449 code is an emissions related leak rather than a restriction is it not? This would make me think gas cap first. (Which actual code were you getting cujo?) Second the updated vent valve is only about $30, not $200. Last, I am a Ford man...I just inherited this one and intend to take care of it until my son is old enough to drive it. Neither truck has been to the strip, nor are they likely to ever. Stock this truck had 50 more HP than my F-150 did, but not only was GM not an option, I also had to have a 5-speed. Also, the 281 STILL had nearly the torque of the larger 327. They are basically the same trim otherwise, except I got all 4 doors and about 6" additional height. ;) Oh yea, my door hinges are also as solid as the day I got it where as the Chevy's doors are about to fall off with half the mileage. ;)

The code I was getting was P0455 (Evaporative System Leak) and my DIC had the message "Tighten Gas Cap". My gas cap looked almost brand new, but I'm guessing the o-ring was dried out and was the source of the leak. The tech also replaced the Evaporative Vent Valve on the same invoice and again posted the same P0455 code. Hope this helps.

Im getting a p0449 code on my 99 silverado 5.3l Can someone help me out with pictures of location please?