Sniper install: Fixed orifice PCV valve? (1 Viewer)

[brian az]

I've been reading too many posts on the Holley forum while I'm doing my Sniper install. There are some pretty strong feelings there that a traditional PCV valve should't be used, rather a "valve" with a "fixed orifice" should be used instead. The gist of the arguments are that the variable nature of a traditional PCV affects the learning of the Sniper. See here, here, and here for example posts. What do you all think?

There's also this video:

If your having issues with getting a good tune with your aftermarket fuel injection systems you might want to look at you positive crank case ventilation valve. The factory variable spring loaded valves can create havoc in your tune. When your trying to dial in your Tip In or Acceleration pump the last thing you want is to be fighting with and opening and closing PCV valve. Especially if you use auto tune A fixed orifice valve is way more consistent . The variable valve with be better at evacuating gasses but that doesn't matter with your car or truck does not run right. Most aftermarket Fuel injection systems check your load using a MAP sensor which is directly affected by a opening and closing valve. The spring is not a precision part and behaves differently and different temps. The valve opening at throttle tip in is not good.

....and this video:

I was having IAC problems (going to 100% for no reason causing car to accelerate without touching gas) from the Holley Sniper EFI throttle body. The video was made for those people on the Sniper EFI forum. Some people said my issue was caused by a stock PCV and a fixed orifice PCV would be better for the Sniper system. It actually IS better. The engine ran a bit smoother in spite of the cam. My IAC problem was 95% better which was the hole point. Since this video I have been using a fixed orifice PCV (like modern cars use today) and have been happy. I was trying to achieve a better driving car and I accomplished that. If you are running a carburetor, I doubt it would matter which PCV you used. The normal stock type PCV caused some weird vacuum signal to the ECU and made the IAC act up.

Another argument against the traditional PCV is that could stick open, causing the Sniper to add more fuel to compensate for the additional air intake and causing the engine to rev higher, possibly creating an unsafe situation if it happened while driving. See here and here.

 

[OSS]

PCV is an emissions reduction method. Engines in the early 60s didn't utilize it. Crankcase back then was vented directly to atmosphere.

 

[sims]

I started my Sniper install with a new OEM style PCV valve. I haven't noticed any wacky IAC issues with the Sniper on the 2f. It seems like many of the Holley forum posts are dealing with high performance installations. IMHO a fixed or variable orifice PCV valve (as long as they're both clean and functioning) won't matter too much on the 2f. If you feel like you are experiencing any symptoms, try a fixed orifice and see if it helps. I would be interested in your results.

SimS

 

[gbogh]

Dual Flow Adjustable PCV Valve – M/E Wagner Performance Products - http://mewagner.com/?p=444 "problem solved"

Edit: as the link title states, this pcv has 2 tunable circuits. If you're having pcv problems, this could give you a more stable flow that you can mess with to get your desired flow/pressure

 

[MoaByte]

I attached my PCV to weak vacuum at the air filter along with the charcoal canister. It seems to work just fine, no smells, no vac or pressure in the tank either.