Catch can pcv problem

**Blackbird6** · 03-15-2016, 06:01 PM

I have a 96 Pontiac formula ltx and i installed a catch can with a breather on top. Im pretty sure the breather gives the car a vacuum leak but the engine runs great. But the vac leak is making the pcm give fuel trims up to 25% . So intried to hook up the pcv system without the can and i dont get the fuel trim but it runs like crap and loads right up like it has a vac. Leak. I dont understand what is going on. Has anyone else ever had this problem. And can 25% hurt anything at idol or even going down the road. I just wanted to put some time on the car before i get a dyno tune done but i wont drive it if fuel trim numbers can hurt it. Any info would be great. Thanks.

**shownomercy** · 03-15-2016, 06:06 PM

Gonna need more info than that.

What can?
Hows in plumbed?

Pictures? Etc.

**Blackbird6** · 03-15-2016, 06:19 PM

How do i load pics. It is justba cheap can that is plumbed in between the pcv checkball on drivers side manifold and the other hose goes to the front of manifold. The passenger side hose out of valve cover goes to throttle body. All emissions and egr stuff deleted

**Injuneer** · 03-15-2016, 07:44 PM

Why did you install a can with a breather, in that location (between the PCV valve and the vacuum source)? The breather is just a huge vacuum leak, that renders the PCV inoperative.

In what LTFT cells are you seeing the +25% LTFT's? That's the max extra fuel they can add.

**Blackbird6** · 03-16-2016, 12:37 AM

Yes i am seeing 25 in the LT trims. I didnt realize what i was doing by venting the catch can and causing a vac leak. But what i dont understand is why it runs better with vented pcv. If i hook it up stock it runs bad and loads up. Could the pcv check valve be stuck. Im stumped.