RJC PCV causing high idle??

[Dr.drivability]

Installed RJC brass pcv valve now idles high. Put a/c delco back in and idles normal. Ideas???

 

[berserker6]

Subscribed. I was thinking of getting one of those.

 

[TurboDave]

Installed RJC brass pcv valve now idles high. Put a/c delco back in and idles normal. Ideas???

If that's all you have in the line, then of course you have the problem.

I don't care what anybody will tell you, those brass check valves are Not a suitable replacement for the proper PCV. They are an unmetered vacuum leak when used by themselves.
YOU MUST USE THEM IN LINE WITH THE PROPER PCV.!!!!!!
They are a check valve for keeping boost out of the motor, and they do that well.

The whole system is calibrated to assume a certain value of vacuum allowed through the correct PCV.

Need proof. Suck on the vacuum side of the good PCV, notice there's resistance there. Now suck on the vacuum side of the check valve. Notice there NO resistane there at all.

You've just injected a larger than expected vacuum leak into the system.

Use it in line with the good PCV.

 

[davidf]

^^^^Actually mines different. I'm just running the RJC valve at the moment but have'nt driven it hardly since install. But when I suck on the check valve I find it rather hard to do. Seems the spring in my RJC is pretty heavy. This is intresting. Any ideas?

 

[TurboDave]

^^^^Actually mines different. I'm just running the RJC valve at the moment but have'nt driven it hardly since install. But when I suck on the check valve I find it rather hard to do. Seems the spring in my RJC is pretty heavy. This is intresting. Any ideas?

Compare it to to a real PCV. See if it's harder or easier. I doubt you'll find it the same.

 

[bmackinnon]

But when I suck on the check valve I find it rather hard to do. Seems the spring in my RJC is pretty heavy. This is intresting. Any ideas?

The 'crack' pressure of the spring (initial opening force) on the RJC check valve may be hard to overcome by sucking, but once it opens, it's a zero restriction, wide open vac leak, like Dave said... must be used inline with a proper PCV valve, which is really just a lightly sprung ORIFICE that precisely meters the amount of vac leak... and is accounted for in the chip calibration...

Dave's absolutely correct.... as usual... :wink:

 

[IrvJr]

I used one with a good pcv and it caused my blm's to go high, once i removed the check valve it went back to normal.

 

[davidf]

Thanks for the great advice. Since Daves always right:wink:, I'm swapping the Delco PCV back. I only put it in thinking it was much better than OEM unit.

 

[Dr.drivability]

Thanks for the great advice guys!! Put my delco unit back in and high idle gone!!! Wish RJC would chime in!!! Dave