Canister Purge Solenoid Bypass

DoubleHighC · Post by **DoubleHighC** » Fri Nov 12, 2004 12:07 am

Since I'm too stingy to pay for a new Solenoid, I tried yanking the old one and spraying it with penetrating oil, alas to no avail. My new plan is to just bypass the thing, but I wanted to check with the experts before I did it.

The plan:

* Pop a 200-ohm 1-watt resistor in to fool the ECU
* Run a hose from the canister right to the throttle body

Any problems with this approach? Thoughts are appreciated. Thanks!

vrg3 · Post by **vrg3** » Fri Nov 12, 2004 12:38 am

I don't know if you want to connect the canister right up to the throttle body... it'll probably mess up your air/fuel mixtures resulting in part throttle weirdness... Let us know how that goes.

tris91ricer · Post by **tris91ricer** » Fri Nov 12, 2004 6:51 pm

mmm.. indeed, the mysteries of the purge canister.. what is it that it does, again? It holds junk from ...???.... and the spits it into the TB so it can be burned in the CC, right?

vrg3 · Post by **vrg3** » Fri Nov 12, 2004 7:10 pm

The canister hold gasoline fumes from the fuel tank, and the ECU allows intake manifold vacuum to suck it in when it deems it appropriate, compensating for the extra fuel.

tris91ricer · Post by **tris91ricer** » Fri Nov 12, 2004 7:49 pm

ooohhmm.. mm-hmm.. well, then.. extra fuel, you say?
i'm lost where the extra fuel comes in..
?

vrg3 · Post by **vrg3** » Fri Nov 12, 2004 8:09 pm

Well, when the canister is purged, fuel vapors go from the canister into the intake manifold, right?

DoubleHighC · Post by **DoubleHighC** » Fri Nov 12, 2004 9:50 pm

That is my understanding. My theory is that hooking the canister right to the throttlebody shouldn't cause any problems. I figure, right now, I'm probably running slightly lean. If I bypass the solenoid, I'll be 'purging' whenever the engine is running. If there's nothing to purge, I don't see the issue.

I don't have time to play this weekend, so I'll give it a shot early next week and let you know what happens. If you don't hear from me, I blew up

[edit for terrible typing skills]

vrg3 · Post by **vrg3** » Fri Nov 12, 2004 10:24 pm

Well, assuming you use the original purge nipple on the throttle body, you'll actually only be purging when off idle. It's a ported vacuum source.

Why do you figure you're probably running slightly lean right now? Unless something's wrong with your engine management system you should be running pretty close to stoichiometric at idle.

I have a feeling that you'll get weird stumbling right as you tip the throttle open, but let us know what really happens.

DoubleHighC · Post by **DoubleHighC** » Mon Nov 29, 2004 3:35 am

Well, I completed my CPS Bypass, and I can report no strange behavior at any throttle position.

I did several hundred miles of interstate driving, as well as a fair amount of town and rural driving with the canister plumbed directly to the throttle body.

I have noticed no hesitation,or stumbling of anykind. It is also possible that my milage has gone up very slightly, although more time will need to elapse before I am certain. All in all, I'm very happy with the result.

vrg3 · Post by **vrg3** » Mon Nov 29, 2004 3:37 am

So you just hooked the canister straight to the nipple on the throttle body?

Interesting that it didn't affect drivability... I wonder if it affects emissions on a non-turbo car.

Wait -- you do have a non-turbo car, right?

WRXdan · Post by **WRXdan** » Mon Nov 29, 2004 5:31 pm

Did the 200-ohm 1-watt resistor solve the SES light?

legacycentral bbs

A forum for 89-94 BC-BF(BJ) Legacy Owners and Fans

Canister Purge Solenoid Bypass

Canister Purge Solenoid Bypass

UPDATE