Where does this go?

[ClayW]

I can't remember or find where this hose under the bottom of the throttle body goes. Help!

The M20 is from a 1991 325i.

Thanks in advance.

[peterman]

There should be a canister down there with a bung on it... It's low

[CorvallisBMW]

Ya, charcoal canister. That's where it goes.

[ClayW]

Ya, charcoal canister. That's where it goes.

So, in the event that I installed this M20 into a 2002 with no charcoal canister, can I leave this venting to the atmosphere? Maybe throw a filter on it? Do I need to cobble together a charcoal canister to prevent gas smells?

[CorvallisBMW]

Your 2002 likely just vents it's gas tank to atmosphere, so you'd just need to plug the hole in the throttle body and you're good to go.

[ClayW]

Your 2002 likely just vents it's gas tank to atmosphere, so you'd just need to plug the hole in the throttle body and you're good to go.

Ah, now I see. That electric valve takes gas tank pressure, which was routed through a charcoal canister, and lets it back into the intake stream. I might actually be able to route it per the original design, using the 2002's original plastic gas line as a vapor line.

Thanks!

[peterman]

So, in the event that I installed this M20 into a 2002 with no charcoal canister, can I leave this venting to the atmosphere? Maybe throw a filter on it? Do I need to cobble together a charcoal canister to prevent gas smells?

I thought I recognized a steering box there... That red cap gave it away. I guess the master cylinder and reservoir should have been an indicator as well.

[CorvallisBMW]

Ah, now I see. That electric valve takes gas tank pressure, which was routed through a charcoal canister, and lets it back into the intake stream. I might actually be able to route it per the original design, using the 2002's original plastic gas line as a vapor line.

Thanks!

Exactly. As long as you're not using a standalone ECU (a la megasquirt) the little electric valve will continue to function as long as it's plugged in. The ECU opens the valve periodically in order to pull vapors stored in the charcoal canister into the engine, where they are burned in normal combustion. And because the vapors are pure fuel vapors, it does not cause any fouling or oil mess to build up. You can technically route any gas tank vent line into a charcoal canister, and attach the hose you're holding to the outlet of the canister. The system will operate as intended.

[Kershaw]

I did not know that, thanks. So what's the best course of action when running megasquirt concerning the charcoal canister?

[CorvallisBMW]

AFAIK MS cannot control the canister valve, so I simply ran the line from the canister straight to the TB, essentially removing the little electronic valve from the equation.

[nando]

AFAIK MS cannot control the canister valve, so I simply ran the line from the canister straight to the TB, essentially removing the little electronic valve from the equation.

yes it can. You use a spare PWM output. it runs at ~90hz - just set up a generic PWM output table that opens it under vacuum. I've been running mine that way for years.