Im removing the last bits of crap under the upper inlet manifold including the vacuume rack and was wanting to remove the purge control solenoid and its attachments (catch tank ect). I need to know exactly what its purpose is, ive searched and found out that basically that it vents fuel vapours from the petrol tank.
can someone answer any of the following:-

1) when does the ECU use the purge valve (start up,, high rev ect?)
2)will removing it cause any adverse affect (poor fuel economy, poor running ect)
3) will removing the solenoid on a standard ECU make it run in limp mode (i think not?)

anyone?

 

I usually leave it alone unless I'm setting a car up to run 2 fuel feed lines. In that case I sometimes use the vent line that runs to the purge control solenoid. Its purpose is to control the vending of gas vapors from the fuel tank. It is illegal to vent these to the atmosphere. It you follow the line it runs to a charcoal canister under the intake elbow and then another larger one back by the fuel tank. Removing it and venting the line may result in smelling fuel vapors.

 

So it wont affect the running of the car , even if i plugged the line .From what your saying rotary experiment it sounds like its just another one of them enviromental friendly gadgets, yes?

 

Just leave it there with the system intact. There is no performance benefit from removing it.

 

you will still need to vent the gas tank somehow. the solenoid prevents the purged fumes from screwing up the air/fuel ratio. I dont know under what circumstances the ecu tells it to allow for purging.

 

The fumes stored in the charcoal canister (back near gas tank) are drawn into the engine to be burned when the solenoid opens. The FSM describes all of this, and this is a very common system on modern cars.

FWIW I've seen a bad purge control solenoid trigger a CEL on an OBD2 car, but no idea with the stock ECU on an FD.

 

I cant see how its really important to vent the gas tank,,,most older cars never had this feature??. I was wanting to remove it just for that, 1 less solenoid few less pipes look LOL.

 

In hot environments you can lose a lot of fuel to evaporation without some sort of system. Ive seen test data from Arizona which shows upwards of a few gallons per week.

Most modern control systems activate purge at cruise and use O2 feedback to determine the rate. It is difficult because there is no way of determining how much fuel is in the can. I think the FD does this as well.

 

They you have an ugly empty bracket there.

 

i talked to our fleet mechanic at work. He said 90% of cars that do have a bleed system like this, are either not functioning correctly or not at all. When i open the gas tank on my fd, there is pressure being released, it hisses for a good 3 seconds.

it seems to me that disabling the purge control and plugging the line couldnt have any ill effects, as long as you open the gas cap slowly. BUT, i have no idea! lol. im just drawing a conclusion from things ive read and mechanics ive talked to.

 

on a car i did a while ago, i left the line unhooked, everything seems fine. I would not block it though, if your tank comes under too much pression it might be dangerous. You might get some fuel smell from the line though in the engine bay. Just leave it unplugged but don't cap it.

 

Any body else got more input on this,,,id maybe like to cap off the line under the bonnet and maybe drill a tiny hole in the fuel cap to releive pressure?? any ideas. I have to agree also that when i unscrew my fuel cap theres a 3 second long hiss, is mine not working?

 

they are all like that.

 

+1

Removing the purge system will result in saturation of the charcoal canister and pronounced fuel vapor odors. Note that fuel tanks must be vented as atmospheric pressure must displace the fuel that is removed otherwise the tank will collapse.

My FD's purge system still works fine with its original components after 13 years & 160k miles.

 

There is possibility if the gas tank venting system is plugged that you will create a vacuun inside the tank and loose fuel pressure. I know from personal experience when I was young & dumb.