Can breather on valve cover cause stumbling in high rpms?

[5.0 Hatch]

I went to the track this weekend to see what my car would do. On the first pass the car blew oil out the driverside valve cover and made a huge mess on my firewall and exhaust but ran 114mph. So then i realized i needed some sort of vent. I took my buddies breather filter off his car and stuck it in plass of my oil fill cap. Made 2 passes without blowing oil out, but it would stumble a bit at around 5300rpms in 3rd gear but ran smooth the rest of the time, but i dropped to 113mph on the last 2 runs.

i tightenend up the belt on the s/c and put some belt dressing thinking that it was belt slip and that didnt seem to help. Only other thing would be the breather right??

[brian88lx]

where was it spraying oil out? the filler neck?

[5.0 Hatch]

no the back side of the driverside valvecover.... between the valve cover and the head

[UNTCHBL]

only other thing that could effect the mph being 1 slower would be about 10 thousand things man.

However, with the breather in the valve cover, you are getting some unmetered air, which will have an effect on the overall feeling and possibly the performance of your car. I'm not sure what the performance gain or loss would be, I'm just saying it's possible. Maybe it is what is causing the stumbling, maybe not. I'd take it off and see if that fixes it. Or atleast that's what common since is telling me.

And I would say, that maybe you should retighten that valve cover back down. normally most cars blow the pcv valve out, or the dipstick tube, long before a valve cover gasket.

Brandon

[5.0 Hatch]

1mph doesn't bother me at all. Basically I made one pass with the factory oil cap on and blew oil out all over the place. Next 2 passes were ran with the breather and had no oil issues only stumbling at around 5300rpms to where I had to shift early(which could account for the 1mph).

I guess at this point i pretty much know that the breather is causing the missing but i really can't run without it. What are my other options??

[Orion_134]

Run a line from your pcv to your intake side of the supercharger, possibly with a filter in it. That way, it sees no unmetered air and under load it will not shoot oil into your intake. I have the same setup on my Ranger, just no filter, it fixed some driveability issues.

Jesse