code P0455 "Gross Evap Leak" and the Purge Valve - SaabCentral Forums
*
Home Saab Pictures Saab Classifieds Saab Dealer Listings Saab Forum Saab Forum


Go Back   SaabCentral Forums > Saab NG900, 1994-1998 and OG9-3, 1999-2002 & '03 Convertible (NG=new gen/OG=old gen) > NG900 & OG9-3 Workshop

NG900 & OG9-3 Workshop NG900 (1994 to 1998) & OG9-3 (1999-2002) & '03 Convertible Technical Forum

SaabCentral.com is the premier Saab Forum on the internet. Registered Users do not see the above ads.
Reply
 
Thread Tools Display Modes
  #1  
Old 18th May 2011
jwwells's Avatar
jwwells jwwells is offline
Saab Lunatic
 
Join Date: Oct 2007                                                
Location: Charlotte, NC
My Saabs: 2000 9⁵ 5-speed Stg1 207K Miles
Posts: 1,294
Default code P0455 "Gross Evap Leak" and the Purge Valve

Hey All
I am working on a 99 9-3 Vert that has the P0455 "Gross Evap Leak" code and has been on for quite some time. The gas cap is sealed and all looks good without dropping the gas tank and looking around there. I've been doing quite a bit of research and want some opinions as to the legitimacy of my proposed repair.

Here's a brief description of the EVAP system.
When liquid gas is being filled into the fuel tank and sloshing around there is quite a bit of vapor hydrocarbons which need to be taken care of (not released into the atmosphere). The way they deal with it is vent the vapor first into a canister with carbon pellets in it which absorbs these free hydrocarbons. Then while you are running the engine the vacuum from the engine is used to draw the hydrocarbons out of the charcoal canister and into the combustion chamber to be burned.
Now the purge valve. The purge valve is a simple solenoid which is electromechanical which means when it is supplied power it opens to allow the vacuum to draw the hydrocarbons, but when the engine is off and no power is being supplied it is closed. The P0455 code is thrown when the pressure in the tank is too high and there isn't a vacuum present. This would indicate to the computer that perhaps the gas cap is off or some other leak. This could also be the case if the vacuum from the engine were being blocked entirely.

Here's what I did.

I pulled this purge valve and tried to clean it then after I plugged it back in and tried blowing through it with the engine running (it should be open when the ignition is ON) it was completely blocked no air moving through. So I bypassed this purge valve and used a one way valve from a parts car brake booster vacuum line. It now draws a healthy vacuum and although I haven't driven it for awhile hopefully it will now register the proper pressure (low) in the tank.

Will this work?

Is my understanding and overview of the system correct? Most of this info is from my reading on WIS.

Thanks, sorry for the long post.
__________________
2000 9⁵ Black 2.3 5-Speed TD-04, ECUproject Biopower Tuned Stage 1- 196K miles
2001 9⁵ Black Auto Aero Wagon

www.theSAABguy.com
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2  
Old 18th May 2011
Frank_Drebin's Avatar
Frank_Drebin Frank_Drebin is offline
Saab Lunatic
 
Join Date: Aug 2007                                                
Location: Atlanta-ish
My Saabs: '96 900 `04 9 Arc Vert
Posts: 2,130
Default

Quote:
Originally Posted by jwwells View Post
Hey All
I am working on a 99 9-3 Vert that has the P0455 "Gross Evap Leak" code and has been on for quite some time. The gas cap is sealed and all looks good without dropping the gas tank and looking around there. I've been doing quite a bit of research and want some opinions as to the legitimacy of my proposed repair.

Here's a brief description of the EVAP system.
When liquid gas is being filled into the fuel tank and sloshing around there is quite a bit of vapor hydrocarbons which need to be taken care of (not released into the atmosphere). The way they deal with it is vent the vapor first into a canister with carbon pellets in it which absorbs these free hydrocarbons. Then while you are running the engine the vacuum from the engine is used to draw the hydrocarbons out of the charcoal canister and into the combustion chamber to be burned.
Now the purge valve. The purge valve is a simple solenoid which is electromechanical which means when it is supplied power it opens to allow the vacuum to draw the hydrocarbons, but when the engine is off and no power is being supplied it is closed. The P0455 code is thrown when the pressure in the tank is too high and there isn't a vacuum present. This would indicate to the computer that perhaps the gas cap is off or some other leak. This could also be the case if the vacuum from the engine were being blocked entirely.

Here's what I did.

I pulled this purge valve and tried to clean it then after I plugged it back in and tried blowing through it with the engine running (it should be open when the ignition is ON) it was completely blocked no air moving through. So I bypassed this purge valve and used a one way valve from a parts car brake booster vacuum line. It now draws a healthy vacuum and although I haven't driven it for awhile hopefully it will now register the proper pressure (low) in the tank.

Will this work?

Is my understanding and overview of the system correct? Most of this info is from my reading on WIS.

Thanks, sorry for the long post.
You would do better to disconnect it and seal the line from the TB. Let the Evap valve vent to atmosphere. Having a constant pull will surely cause fuel flow issues at lower fuel levels.
Reply With Quote Quick reply to this message
  #3  
Old 18th May 2011
jwwells's Avatar
jwwells jwwells is offline
Saab Lunatic
 
Join Date: Oct 2007                                                
Location: Charlotte, NC
My Saabs: 2000 9⁵ 5-speed Stg1 207K Miles
Posts: 1,294
Default

Quote:
Originally Posted by Frank_Drebin View Post
You would do better to disconnect it and seal the line from the TB. Let the Evap valve vent to atmosphere. Having a constant pull will surely cause fuel flow issues at lower fuel levels.
Well that would put me in the same position I am in now throwing the CEL and it won't pass inspection. Just curious... how would a vacuum in the tank cause fuel flow issues?
Thanks for the input!
__________________
2000 9⁵ Black 2.3 5-Speed TD-04, ECUproject Biopower Tuned Stage 1- 196K miles
2001 9⁵ Black Auto Aero Wagon

www.theSAABguy.com
Reply With Quote Quick reply to this message
  #4  
Old 18th May 2011
watkins's Avatar
watkins watkins is offline
Saab Lunatic
 
Join Date: Mar 2008                                                
Location: Salem, MA
My Saabs: '99 Viggen
Posts: 1,619
Default

The purge valve is not open all the time when the engine is running. Only under certain situations. It also cycles rather than staying open or closed. The blow test doesnt mean much
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Reply

Bookmarks

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the SaabCentral Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools
Display Modes

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
"HOW TO" replace EVAP Purge Valve on 2.8T V6 Ferms_93_2.8T 9-3 Sedan, Cabrio ('04+)/Combi & 9-3X Workshop 81 4 Weeks Ago 08:19 AM
P0455-EVAP large leak-?? jswain 9-5 Workshop 9 10th April 2011 09:06 PM
"Gross evap leak" code....??? nightskyisme 9-5 Workshop 36 1st May 2010 06:38 PM
P0455 Gross evap leak questions TwoManyPassats NG900 & OG9-3 Workshop 9 4th September 2009 12:02 PM
TPS or EVAP purge valve lancelot8602 NG900 & OG9-3 Workshop 3 9th July 2008 02:34 PM


All times are GMT -4. The time now is 01:33 AM.



Powered by vBulletin® Copyright ©2000 - 2014, vBulletin Solutions, Inc.

top of page | sitemap | email us



copyright © 2003 - 2011 saabcentral.com, All rights reserved http://www.whiter.co.uk - valid xhtml - valid css
SaabCentral is an independently run website and is not affiliated in any way to Saab Automobile AB.


Garage Plus vBulletin Plugins by Drive Thru Online, Inc.