Breather=Unmetered Air !!??
05-31-2007, 12:55 PM
#41
Gotta love the mis-information in this thread. Alot of poeple waste $$ by just running a catch can and leaving the fresh air hose alone, but on my car thats where most of the oil was entering my intake. I know I have an LT1 but the pcv system works the same way. I'm running a breather on both valve covers, and a pcv line with a catch can in it. This way no oil enteres my intake, and the oil still stays clean like it would with the stock pcv setup. The computer can adjust fine with the un-metered ait, thats why we have 02 sensors.
05-31-2007, 11:16 PM
#42
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With my Z28, I added a billet breather, more for looks than anything since I don't have a problem with oil that a catch can is needed(least not yet). Car has 40k on it and added LT headers about a year ago. when the LT's went on, I was having a big problem getting my fuel trims correct, so one day was thinking about the breather. Removed it and the fuel trims are perfect now. I put 100's of miles trying to get the fuel trims where they should be and finally they were good after I removed the breather. I didn't do any mods on the lines going into my TB, so that was with just adding the breather. Before the LT headers, my fuel trims looked fine, so was only after the LT's, my trims went off from the breather. I hear you can do mods on the line to stop extra air getting in, but I haven't done it. Just my experience with it.
05-31-2007, 11:57 PM
#43
Why introduce unmetered air if it can be avoided by capping all of the ports off? If you run a breather you should not have a pcv system on the motor, that is what the breather is for. It eliminates oil from going into the intake by getting rid of the closed pcv system.
06-01-2007, 10:12 PM
#44
I had a breather with pvc and unmetererd air did not affect my bolt on z28 but with my ss and all the mods in sig I got a ses light for lean bank 1 and 2.....got a catch can and removed breather and everything is straight now.
Last edited by AFASTYZFR1; 06-11-2007 at 09:27 AM.
06-01-2007, 10:49 PM
#45
98camarod, i think you finally got through. good advice btw. believe it or not the stock PCV is the best way to go, by itself. on my big inch pontiac, i tried breather only. all i got is oil all over and blown out dip sticks. then tried breather/PCV together. all i had was oil all over the side of the engine and a lean condition. then went bone stock PCV where i ran the line from the valve cover to the underside of my air cleaner (carbed). BINGO! 469 cid at 6700 rpm and now blowing oil, except for very little out the exhaust, and my carb was doing what it was tuned to do. believe it or not, those engineers at GM are pretty smart about this PCV stuff.
06-02-2007, 09:52 AM
#46
Originally Posted by dirty howie
In an effort to keep oil out of the intake manifold/combustion chamber..... Many of us run a catch can in the PCV line (valley to intake manifold line). Then instead of running the passenger valve cover line to the TB (or air bridge on LS2) we put a breather in place. Or cap the vent and put in a breather oil cap. DH
Last edited by RevGTO; 06-11-2007 at 11:22 PM.
06-11-2007, 08:29 AM
#47
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When I first put my catch can on, I had the breather in place, but did not use the PCV. The car idled high and erratically, like it was definitely drawing air from somewhere. When I put the PCV back in with the catch can, the car idled just fine.
