Hi,

I'm trying to find out under what conditions the stock ECU
opens the EVAP canister purge valve.
I know it might be different between the two emission types, but
still should be similar.

Does anyone have any info on how Hyundai does it?
Or that matter, any other manufacturer? I'm not sure if its
an OBD2/EPA spec, or its up to the manufacturer.
I suspect the latter, but appreciate any info.

Thanks
Bry

 

I hope this helps.

P0441 CIRCUIT DESCRIPTION
CODE: P0441
CODE DESCRIPTION: Evaporative Emissions Control System Purge Valve Permanently Open

PRIMARY COMPONENT: Purge Control Valve
SECONDARY COMPONENT: Fuel Tank Pressure Sensor
SYSTEM(S): Elantra, Tiburon (Bosch)
NORMAL PARAMETERS: 27 ohm resistance

The evaporative system reduces hydrocarbon emissions by trapping fuel tank vapors until they can be burned as part of the incoming fuel charge. Evaporating fuel is stored in a charcoal canister until it can be flushed into the intake manifold.

FAILURE CONDITIONS
If the stored evaporated fuel is not being flushed into the intake manifold as expected during two back-to-back trips, this code will be set and the Malfunction Indicator Light (MIL) will be turned on. The purge control solenoid valve is stuck in the open position so that fuel vapor is constantly allowed to enter the intake manifold and no pressure ever builds up in the canister or fuel tank.


Details: The code will be set if the following conditions are met:

Engine has been running for 16 minutes 40 seconds

Engine idling
Vehicle speed = 0 mph
Engine temperature at start is above 20°F (-7°C)
Altitude is less than 8,000 ft
Evaporative emission control system fully closed for at least 5 seconds but differential pressure is less than -8 hPa or vacuum built up but fuel tank differential pressure is less than -20 hPa

 

hmm, thanks.
it obviously uses tank pressure, and maybe canister pressure.
i dont have a canister pressure sensor.. or even a tank pressure
sensor come to think of it.
it doesnt say anything about what normal conditions are though.

if the vapour is fuel rich, it could affect the A/F ratio, so I imagine
the ecu only opens the valve at a particular time.

thanks for the info,
care to speculate?

bry

hey, go to bed smile.gif

[ March 22, 2003, 03:39 AM: Message edited by: bryfx ]

 

I haven't the first clue as to how to "go around it", but I'm pretty damned sure this is the source of the "PFFFTAANK!" noise I hear once in a while from the front of the car while when turning the key to the ON position. Whoops, there goes some hydrocarbons wink hehe...

I completely gutted the wiring that goes to the EVAP canister in the front corner of the car, and so far it's still going along just fine. I've been looking at rerouting my fuel lines to get around it all, but honestly the job looks to be a severe PITA and the end result will probably be nothing more than eliminating the occasional wierd noise wink

Hardly worth my time so far as I'm concerned, so I've just left it. I suppose with enough wiring, fiddling and trickery I could probably get the Haltech to operate that thing based on the readings of an external pressure sensor or something. Bleh, who knows...

Edited to omit some incriminating information - hehe wink

[ March 25, 2003, 10:57 AM: Message edited by: Red ]

 

Heh!

I think mine will stay that way too.

The pssht at start, could be a mixture igniting.

when you power up the haltech, it grounds both ignition
output temporarily. This causes a spark, which can light
any mixture left in the cylinder.

This happened to me while i was trying to fire it up, all the
cranking left some fuel in there, then it went pssht.
scared the
beejesus out of me, though i blew somethin up! wink

 

Hell, that must be what that noise is then! That would make perfect sense too, because it usually doesn't happen on the FIRST attempt to start, but instead happens on rare occasions when the car doesn't start on the first try.

Wow, learn something new everyday smile.gif I've had it for almost a year and never actually new that, goes to show you I certainly don't know it all

 

Heh, I've had my scope on all the outputs