A few more 2c worth...
He sure has! Esp when he says "You can blow like the wolf" Maybe he's following a very lengthy linear progression (or a few too many lines?)Originally Posted by Rustam
Hi Rustam, thanks for posting. Good to see you're still around too :-)
I had EVAP valve troubles before. On one it was the line, on another the valve. On later BMWs the plastic PCV plumbing cracks and fails at age, and one of the very common codes thrown is 'EVAP valve/solenoid valve'. I actually did have a valve fail on the e46 M54 (causing an open-circuit code, which was the valve (which is available cheaply as an OEM item from China, and physically won't be far off fitting the e34 either).
On my older e34 535, the valve's inner seal inside the evap valve failed, so idle was rough. I cleaned it with fuel and alcohol and it began sealing properly again, so it passed the blow test!
As I understand it, the evap valve draws air through the valve when the ECU decides to open it (when the engine is at speed) as this helps clear air pressure in the tank on hot days without pollution. Also, once the engine is running, warmed fuel begins returning to the tank, causing evaporative pressure to increase. The canister and its holes prevent stale fumes being emitted once the car is parked and engine shut down- especially if you leave it in a sunny place, and/or above hot asphalt surface so the fuel tank heats up. In the old days, when they first installed carbon canisters with carbs, (E3/E9?), they just had the canister, but the carbon gums up faster if the engine doesn't help remove the vapours during use, so it was worth installing the valve and a third pipe to link it to the intake.
In the later cars, the ECU has a fair bit of logic around opening this valve to meet an improved emissions regime/more active PCV cycle.
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