Evaporator System Help

[ClayW]

I need to understand the workings of the evaporator valve.

I'm almost done installing an M42 into my `67 1600 and I found this plug:



According to a forum member, this should go to an evaporator valve like this one:



I'm sure that I can get one of these, but I have a few questions before I do:

1. How would I hook it up? Line to the gas tank? Would that cause any issue with my non-E30 gas cap/tank/etc.?

2. Do I even need it? Is it possibly one of those unnecessarily complicated parts that US cars are burdened with for emissions reasons? If I don't need it, what's the best way to bypass it?

Thanks in advance!

[M5wanaB]

You do not need it, I am runnng my M42 powered 2002 without it but it does throw an engine code. If you want to hook it up then run it in line with the blue plastic fuel vapor hose that comes from the vapor canister in the trunk. You will notice a vaccuum port on the left side of the throttle body that the other end hooks up to via rubber fuel hose. I havent figured out how to bypass it so not to get a CEL yet but if I do I will post here. You can go to Pick n Pull and pull one of these out of any OBD1 BMW, it should be connected to the Charcoal canister via rubber fuel line. I deleted the whole vent system and went the Euro Route which just runs a line from the filler neck out the bottom of the trunk and it vents to the atmosphere.

[ClayW]

So, I really only need to worry about it if/when I run a "Check Engine" light?

For now, if I go without it and plug the throttle body port, will the car run worse, better or with no difference? Jake mentioned that he encountered some issues with too much vacuum in the tank.

Incidentally, I don't have an extra line to the trunk. My `67 had the Euro venting solution.

[M5wanaB]

stick with the euro vent. You will not notice any drive-ability issues. This is really just essentially just a smog device. It is meant to burn the extra fuel vapor through the engine instead of venting it to the atmosphere. I believe if you could find the proper resistor you could hook it up to the plug for the valve and the CEL would stop coming on as well. You just need to trick the engine into believing the valve is hooked up. OR you could just hook up the valve and let it hang in the engine compartment not hooked up to anything but the plug. That will also take care of the CEL.


BTW- I would take out that AFM extension harness as well. Mine ran like crap with that hooked up. When you get it running try running with and without it. My car had a huge flat spot at 3/4 throttle with it hooked up.

[cristimm]

You do not need it, I am runnng my M42 powered 2002 without it but it does throw an engine code.

To avoid the code just plug a 1k resistor in that connector.