RJC PCV Experience


Active Member
Oct 1, 2017
I just wanted to make a quick post to let the members know my recent findings with my RJC PCV valve. It had been on the car when I bought it last year and I noticed straight away on my first few drives with the car that the idle BLM was at 142, but would come down quickly once moving off idle. I never gave it much more thought as all vacuum lines are in good shape, BLMs were fine in all other driving conditions, and the car ran good otherwise. Upon looking up the topic on the board here I found that others were getting high BLMs at idle with these PCV valves as well without the stock PCV valve in place.

Fast forward a year and I decided with all the virus downtime to put some time into the car. I changed out injectors and chip with the 60 lb combo from TT. I noticed again when idling for the first time that the idle was horrible and after the first drive it was better/about normal. I then noticed on further driving that the cold idle would drop very lean to about 115 sometimes below 100 mV on the SM at idle with a very rough feel. The idle BLM again just pegged at 142 since Eric does not let his chips go past 142 at idle for BLM. I broke out the starter fluid and started spraying areas for potential vacuum leaks - MAF tube checked good, all piping couplers checked good, drivers side intake and hoses no change in RPM, vacuum block area all good, and then spray the PCV area with an immediate rise in RPM. Bingo. I had on the shelf a stock replacement PCV, a US Plastics viton seal check valve to install inline, and a new PCV hose which I had purchased after reading a majority of the prior RJC PCV valve threads. I got it all installed in the car, reset the PCM by disconnecting the orange wire at the battery, and went for a little drive. I’m pleased to report that idle BLM now has dropped to 133 and the idle has greatly improved. I verified this again the next morning on a cold start with open loop idle now enabled after the relearn drive that idle never went lean and idle BLM at 133.

Sorry for the long winded post but wanted to try to help others that may be fighting a lean idle issue and an RJC PCV valve on their car. Spool on!
Had the same issue myself. Blms i could never get them adjusted to acceptable range and i was going crazy, it wasn’t until I stared at my engine with frustration and began listing to what sounded as an internal air leak.

I then began to pinch all my vacuum lines and found the rjc pcv valve was the culprit. after replacing the valve the internal air leak went silent and it was at that moment that i knew the problem was fixed.
I know I had read that these valves flow much greater than the stock PCV and the PCV itself is just a controlled vacuum leak really so I was pretty sure this would cure my issue. I was really hoping it wasn’t a grommet issue as I did not want to deal with that headache. I know others have also just put a stock PCV valve in and then used the RJC valve as a check valve, but that seemed a lot more cumbersome to install inline compared to the check valves from US Plastics that I had found mentioned on the board somewhere on PCV valves. I like simple fixes that take less than 10 minutes.
I have one of the US Plastics check valve brand new you can have for shipping. I decided simply cap off the pcv valve and eliminated the whole oil sucking problem for good. Got rid of the catch can as well. Brad
I never saw the need for an aftermarket check valve as long as you were using the original AC 893 PCV valve. I have tested quite a few of them and they work really well as a check valve. They leak a little but is negligible. The aftermarket PCV valves like Purolator and others do not fare as well. They leak quite a bit under boost conditions.
The odds of someone finding a pure stock AC 893 PCV is highly slim unless they grabbed a 10 pack years ago. I couldn’t find a true stock PCV valve anywhere from vendors, GM parts warehouses, etc (not that I turned over every stone possible) and the few private party folks I’ve seen the last year or so ask $25 to $30 for something aftermarket for $7.00. I would guess that most TR owners/newer owners out there these days run an aftermarket and the check valve for an extra 2 bucks is cheap insurance against pushing past the rear main.

Looking at my set up at a glance you would never seen the check valve unless you were specifically looking for it.
I have a standard brand one you can try...just pay the cheap shipping ...same ones kirban and highway stars sells ...
if darkstar72 wants to give the standard brand a try LMK..im sure shipping will only be around 3 bucks....
I think maybe I didn’t write my original post correctly. I have already replaced my PCV with an aftermarket stock replacement from a Buick vendor. My car runs great. My post was for informational purposes really.

I would like to know though where I can a true stock AC Delco CVC893 for $8.00. I would buy at least three at that price.
I bought that one. I don’t believe it’s nothing more than a Standard 242. It came in a plastic bag and no markings anywhere on the PCV. If I’m buying what they are advertising as an AC Delco valve then I would expect it to show up on an AC Delco box.
I bought that one. I don’t believe it’s nothing more than a Standard 242. It came in a plastic bag and no markings anywhere on the PCV. If I’m buying what they are advertising as an AC Delco valve then I would expect it to show up on an AC Delco box.
did it work ok ..or you put another stock replacement in..just curious ..you said car runs great...thx for the info
It worked better for me than the RJC valve that was in the car. Will it work as good as a true stock Delco valve...no idea since I don’t have one in stock to compare with.
This may sound dumb, but I put the RJC in between the stock PVC and vacuum port
My BLMs was a little high too ,so I put the stock back in its home BLMs returned to normal. Then I put the RJC check in between. I knew it would hold 25 psi better than possible the stock PVC. No change on BLMs with both.
I don’t think it sounds dumb at all and I had read prior threads advising that a few others run theirs the exact same way with the RJC valve as a check valve for a stock PCV. The check valve from US Plastics is rated to hold a high bit of pressure so I think it will hold up still at 25 psi boost.