View Full Version : PCV and Holley Sniper (or other aftermarket efi)
Otee453
08-26-2020, 12:56 PM
On the Holley Sniper Tech Support Facebook group, there was an interesting post regarding the PCV and aftermarket EFI. Essentially, a traditional PCV valve can create an uncontrolled variable that makes the self learning and tuning of the EFI system difficult or even impossible. This was reiterated by several people including some well known professional tuners.
The fix.... a "fixed orifice" PCV valve.
I'd like to see what some opinions here are, as well as maybe help anyone who may be chasing gremlins with their Holley Sniper.
https://www.youtube.com/watch?v=n0_L7IBgMpI
BradCraig
08-26-2020, 01:45 PM
I personally have not had an issue with the variable PCV valve and have tested with and without it connected. BUT I can see where it may be a problem and it's been on "the list" of things to change for about a year now. :-)
Norm B
08-26-2020, 02:48 PM
I haven't had a problem yet but, my PCV system runs through an air/oil separator before going into the manifold. This may be acting like a restriction and making the airflow more consistent.
Norm
Interesting! How do I identify what type of PCV I have?
Edit: Watched the video and answered my dumb question. :o
Otee453
08-26-2020, 03:08 PM
134334
Sorry guys. The picture is so small.... just click on it and it will open up.
This is a list (from FB) of fixed orifice PCV valves that are readily available. The good news is that they are quite cheap. I'm looking for a nice polished or billet one and the only thing I can find so far is an adjustable PCV that runs $150.
Otee453
08-26-2020, 03:13 PM
Interesting! How do I identify what type of PCV I have?
Edit: Watched the video and answered my dumb question. :o
In the video he shakes the PCV and the traditional one rattles sounding like a ball bearing check valve inside. Also, the fixed orifice one has a small, ⅛" hole in the valve. Not sure if that is a sure fire way of identifying them or not.
134334
Sorry guys. The picture is so small.... just click on it and it will open up.
This is a list (from FB) of fixed orifice PCV valves that are readily available. The good news is that they are quite cheap. I'm looking for a nice polished or billet one and the only thing I can find so far is an adjustable PCV that runs $150.
I just bought this one on Amazon for $5.00. Not polished, but also not $150.00!
https://www.amazon.com/FV410-Positive-Crankcase-Ventilation-Valve/dp/B0010DW658/ref=sr_1_2?crid=1TT6DI0UH3AL8&dchild=1&keywords=fixed+orifice+pcv&qid=1598472597&sprefix=fixed+orifice%2Caps%2C184&sr=8-2
OVCobra
08-26-2020, 05:26 PM
In the past, I have had some success by simply inserting a Holley jet into the spout of the PCV valve (where the hose connects)...this was mostly to address idle issues when using a tight lobe centerline/long duration camshaft.
On my current build, I have installed the dual flow PCV from ME Wagner ( http://mewagner.com/?p=444 ). Again I am using a tight lobe centerline/long duration camshaft and i believe it did improve idle quality. I am using a carburetor so I cannot say whether it would address tuning issues with efi...maybe give them a call and ask/discuss. Nice folks to deal with.
Dave
BradCraig
08-26-2020, 05:31 PM
In the past, I have had some success by simply inserting a Holley jet into the spout of the PCV valve (where the hose connects)...this was mostly to address idle issues when using a tight lobe centerline/long duration camshaft.
On my current build, I have installed the dual flow PCV from ME Wagner ( http://mewagner.com/?p=444 ). Again I am using a tight lobe centerline/long duration camshaft and i believe it did improve idle quality. I am using a carburetor so I cannot say whether it would address tuning issues with efi...maybe give them a call and ask/discuss. Nice folks to deal with.
Dave
Never thought I'd say this, but that's the sexiest PCV valve I've ever seen!
BradCraig
08-29-2020, 09:32 AM
I just bought a fixed orifice PCV, i'll do some before and after logging to see if it makes a difference.
Norm B
08-29-2020, 10:22 AM
I'll be interested in the results. We went for a drive yesterday and I noticed a short period of lean out each time I got off the gas. AFR would go to 19 momentarily then, recover quickly to 14. Could be the standard PCV valve transitioning and adding a bunch of air at the wrong time.
Norm
BradCraig
08-29-2020, 12:38 PM
I'll be interested in the results. We went for a drive yesterday and I noticed a short period of lean out each time I got off the gas. AFR would go to 19 momentarily then, recover quickly to 14. Could be the standard PCV valve transitioning and adding a bunch of air at the wrong time.
Norm
I logged both PCV valves and for my setup i saw no noticeable difference on the logs as far as Actual vs target AFR. I logged at idle and a few runs up to 4k, but in my garage since it was raining. I would say if you are optimizing or hunting gremlins this may be something to consider.
As far as your momentary lean on decel, that is totally normal especially if you have decel fuel cutoff enabled
-B