dgantt

Just got my 1990 vette back from getting heads done. The new valve covers I bought now have the PCV valve on the passenger side. I have a question the original PCV left the valve cover and went where? I have looked for hours and cant find the answer. I have seen that it goes either to the top nipple on the throttle body or somewhere on the plenum. If I remember correct the CCV went to the middle nipple on the throttle body. The shop that put my heads on have it set up different now the driver side valve cover has a filter where the old PCV use to be. The passenger side now has the PCV and the hose is going to the middle nipple on the throttle body. This don't seem right to me. I'm getting hesitation when going WOT and wonder if this is the issue.

Joe C

seems like your shop has it backwards - ??? -- in stock configuration, the PCV valve is located in the LH valve cover, and routes, via an "S" shaped hose to a port on the intake manifold (pic 2). the RH valve cover has a hose coming off the VC, and routes somewhat under the injector wiring harness, via a metal tube, and connects with another short piece of hose, to an upper-rear port on the throttle body, just to the upper, rear-left of the TPS. this completes the factory PCV system or circuit. here's a couple pics from my 90 - hope this helps....

dgantt

Joe C,
Thanks for taking the time to send me those pics, your looks SO clean. Very nice. So the PCV is on the passenger side and is routed the lower intake manifold correct? There are 4 off the throttle body. The bottom 2 close to the IAC the coolant passages, the very top one is the CCV on the drivers side valve cover. Where does the middle port go? I was just confused because a drawing shows the PCV on the drivers side and the CCV on the passenger side. Thanks for the help my friend.

dgantt

Cliff Harris

The filter in the valve cover is now a vacuum leak.

The upper port on the passenger side of the throttle body is a source for metered air (it went through the MAF). That air goes to the CCV (CrankCase Valve) and circulates through the crankcase.

The PCV valve is on the driver's side valve cover and is connected to the intake manifold (vacuum source). There is an air port on the side of the intake manifold between the #3 and #5 runners. Later years have a hose that goes directly from the PCV to the intake manifold (as seen in the second picture of post #2). Early years have a pipe and rubber hose connections. My '86:

dgantt

Hey Cliff, thanks for the reply. I got it figured out yesterday. They had the port on the intake capped off. I put the PCV back on the drivers side and attached the hose back to the manifold. The passenger side has a valve cover filter on it now I capped both TB ports. Cars seems to run a lot better now.

Cliff Harris

As I said before, this causes a vacuum leak and affects your AFR.

You need to get the passenger side valve cover hooked up to the top air port on the throttle body.

MrWillys

He doesn't have a MAF so not applicable.

dgantt

OK gottcha, I'm tracking now. Two questions the valve the passenger side valve cover is it a another PCV valve and it goes to the middle port on the throttle body correct? Only problem now is the new valve cover will not have a oil cap on it.

dgantt

Correct this is a MAP car speed density, so is the open breather on the CCV port still a vacuum leak?

MrWillys

The air intake is passenger and gets sucked in the drivers side. The PCV closes when at zero vacuum like WOT.

MrWillys

No, because you have the ability to correct the programming.

Cliff Harris

The middle port goes to the vapor canister.