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psamp48
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May 29, 2010, 8:32 AM
Post #1 of 8
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1998 Lumina code 446
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1998 Lumina Sedan 3.1
174000 Kilometers
Car runs well, but code 446 happens often. Also, there is a significant amount of vacuum from the fuel tank, it makes a lot of noise after shutting the car off, if I remove the gas cap it has a lot of negative pressure, full or empty. Do you think this is the gas cap or the charcoal canister?
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psamp48
User
May 29, 2010, 6:16 PM
Post #2 of 8
(4739 views)
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Re: 1998 Lumina code 446
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Anyone have any ideas?
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Sidom
Veteran
/ Moderator
May 29, 2010, 9:08 PM
Post #3 of 8
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Re: 1998 Lumina code 446
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The P0446 is an evap code...... Evap canister vent blocked.
That may be a good place to start.........
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psamp48
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May 30, 2010, 3:08 PM
Post #4 of 8
(4727 views)
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Re: 1998 Lumina code 446
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I replaced the EVAP canister vent valve today, also the fuel cap. I'll see how it behaves over the week. I couldn't blow through the old valve. I think it was stuck shut.
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Hammer Time
Ultimate Carjunky
/ Moderator
May 30, 2010, 6:34 PM
Post #5 of 8
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Re: 1998 Lumina code 446
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Of course it was....... It's a vent valve. It rests in a closed position.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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psamp48
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May 30, 2010, 7:10 PM
Post #6 of 8
(4713 views)
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Re: 1998 Lumina code 446
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I found this on the web, also, the new part I can blow through it easily,
The enhanced evaporative emission control system is a result of California emissions regulations that went into effect for the 2000 model year. Most new vehicles sold in all 50 states met those requirements that first year, and today they all do. Techs can tell the difference by looking for a service port cap under the hood, sometimes marked “EVAP.”
Like the earlier systems, the enhanced EVAP system captures fuel tank vapors and sends them to be burned in the engine. The two “enhancements” refer to the on-board diagnostic (OBD) system’s ability to detect leaks as small as 0.5mm and to monitor canister purge flow. The former is required by law to monitor the health of the EVAP system, and the latter is needed by the PCM to control tailpipe emissions and preserve driveability during canister purge. There are several different ways to accomplish these tasks, and of course the automakers have used them all. Fortunately, they’re not hard to understand.
There are two different ways for an OBD system to leak-test an enhanced EVAP system: pressurize it or put it under vacuum. Each has its advantages. Vacuum testing is mechanically simpler, requiring only two solenoid valves and a fuel tank absolute-pressure sensor. But because the vacuum comes from the intake manifold, the drive cycle (the engine operating conditions needed for the test) is very precise, so there’s no guarantee the test will actually run during any given trip.
Leak-testing with pressure requires a pump and extra plumbing, but the drive cycle is less exacting. Ford Motor Co., General Motors (GM) and some Asian models use vacuum tests, while DaimlerChrysler, some Asian and most European models use pressure tests.
In either case, leak-testing an EVAP system requires sealing the system at each end. The purge control solenoid valve is used to seal the system at the intake manifold end, and another solenoid valve seals the canister’s fresh air inlet. This canister vent valve is normally open, and on several models a clogged fresh air inlet has caused problems that turn on the malfunction indicator lamp (MIL), but more on that later.
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Hammer Time
Ultimate Carjunky
/ Moderator
May 30, 2010, 7:17 PM
Post #7 of 8
(4710 views)
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Re: 1998 Lumina code 446
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You might have it then.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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psamp48
User
May 31, 2010, 4:48 PM
Post #8 of 8
(4696 views)
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Re: 1998 Lumina code 446
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The car ran fine today, no codes over 100 kilometer commute.
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