So, my blue headache (bmw 318ti) started having some idle issues. Being excessively cheap, I decided to attempt a DIY fix for my problem. After reading numerous forums, I've found the culprit to be the PCV/ECV valve. This particular part is used to recycle some of the valve cover gasses to maintain some semblance of "emissions standards." However, when excessively worn, the valve allows extra air into the intake causing idle and fuel/air mixture issues.

Well, I don't live in a state that has emissions tests any more, so let's bypass that sucker!

DISCLAIMER: modifying engine components can and will void any sort of warranty (not that anyone on this site is worried about that). Working on cars is dangerous, accept that you will get burnt, crushed, sliced, diced, and killed. With that in mind, watch your digits and be careful. I accept no liability for any modifications that cause engine failure, engine explosion, or cause the engine to disappear into another dimension. Nor do i accept any liability for personal injury, unless there is a wormhole involved, then it's totally my fault.

Step 1: Get the Parts Together

There is a lot of leeway with the actual materials list on this one.

I used:
1x small paint can and lid (this can be substituted for any container, though i'd recommend metal)

1x coupler to fit hose

1x nut to tighten coupler

Length of hose (determined by the size of your engine bay)

Tie Wraps to mount can in engine bay

Tools:
Drill with bits appropriately sized for coupler and vent holes

Step 2: Drill the Lid

It's a pretty self explanatory step, so let me use this time to give you the 'why' of this project.

The point of a catch can is to allow the valve cover to vent any excess gasses and oil particles without dumping them directly into the environment. The can gives the gasses an opportunity to slow down and let the oil/carbon particulates fall out of the stream and stay in the can.

The PCV would normally route these to the intake manifold, however mine is constantly stuck in the open position causing idle issues. I don't feel like spending 50 bucks on yet another piece of plastic, so we'll plug the intake hole on the PCV and call it good.

Step 3: Attach Coupler and Hose

This step is 'overkill' in my book, but it makes it look better and feels a little more permanant.

Push or screw the coupler through the center hole in the can and attach the nut to the opposite side to hold it in place. Push the hose onto the coupler and (if you're feeling frisky) attach it with a hose clamp.

If you don't have a fancy coupler you can just push the hose into the hole in the lid and that should work fine, perfection is not required here!

Step 4: Pop on the Lid!

Press the lid onto the paint can and you are finished (as far as assembly goes)! Congratulations, you've just created a bypass to the environmentally friendly countermeasures on your car!

I have not installed this as of yet, but will update with pictures and results when i do.

Please vote for this in the Jury-rig It Contest! (I was going to put this in the green contest for laughs but decided against it)

Step 5: Update: Installed

The pictures and tags pretty much show the installation in full. Except for putting the PCV Hose back on (pop it back on the exhaust on the valve cover) and routing the hose to the can (I used a long hose so i could reach around the engine bay to keep it in the cooler areas). But those would be different with every engine.

Anyway, thank you again for reading, and after i give it a run-in I'll post another update!

And a belated apology for the cr*ppy pictures, my camera phone sucks :(

Double Update Action!!!!!!

the way I had the hose routed to the can as shown in the pictures was the wrong way to do it. Some of the gasses remain in the hose, cool down, and create a liquid plug if there are 'ups and downs' in your line. Now i have it draining straight down. We'll see how it goes!