PCV help


New member
Hi Everyone,

I'm in the process of resurrecting an old Typhoon that hasn't seen the street in years. The engine was trashed when I got it, so I'm swapping in a replacement.

My question is around how the PCV system is configured (stock) in these. The replacement engine had only a few pieces (I think), and the engine that came out had even less.

1- Does the passenger's side PCV hook up to the nipple facing the passenger's side under the throttle body (circled in image)?
2- If the above is correct, and it connects via the "larger side" of the hose- the other end looks like it connects to the vacuum system. Is this correct?
3- The driver's side PCV just runs from the valve cover into the intake (after the filter, but before the turbo)?

Does anyone have a good diagram of this?

Thanks in advance all. I want to give this the best chance on initial startup of actually running properly.



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DaveP's Ghost

Active member
There are 2 PCV valves on a metal "T" thing on the passenger valve cover. The aft PCV valve connects to the nipple on the throttle body that is a passage to plenum vacuum.

The forward PCV valve on the passenger side goes to a nipple in the crossover before the turbo inlet. The pressure drop across the air filter element provides some 'vacuum' when on boost to continue to evacuate the crankcase. (The aft PCV valve is blown closed during boost.)

The driver side valve cover is just the inlet for air to be sucked across the engine to the PCV valves. It is only a hose that goes to the filtered side of the air cleaner. No valve on the driver side.

The emissions sitcker on the core support has a diagram of the vacuum system. Not real easy to decipher, but it may help.


Well-known member
I have a extra pcv T in my surplus if you don't have one.

Couple pictures of the VECI- brand new one I had in my surplus.

Pretty clear to read if yours is faded, or peeling back.

Mainly dug it out so you can decipher the emissions hose routing.



New member
Very cool, thank you both- I think I was finally able to put it together with this info.

What sent me on this path was these two open ports in this picture on/under the throttle body. Assuming these aren't even part of the PCV system at all.. are they left open? Any idea what they are for.



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Well-known member
Being the parts are off a shared vehicle platform the ports I believe are coolant passages used on ZR1 Corvette platforms.

DaveP is seemingly a expert with that topic and I don't want to cross too far into that territory.

I believe there both capped on our vehicles.

DaveP's Ghost

Active member
The SyTy throttle body is the same as the TPI throttle bodies used on Y and F car from 1985 to 1991. In a normally aspirated configuration, under certain operating and environmental conditions, ice can form in the throttle body preventing the throttle from closing when released. In a turbocharged application, the inlet air is heated by the pressurization, and ice doesn't accumulate. The cooling passages aren't required to be connected on the turbo apps. I have never seen caps on a SyTy, they were left open.

The "C4 ZR-1" or LT5 throttle body is different than the TPI. It has a 7/8" primary bore and two 2.3" secondary bores that begin to open at 30% throttle. The engine runs on the little bore until 30% opening when the secondaries begin to open, and the secondary fuel system is also activated. (I drove my ZR-1 last night to Paul-Z's house for Thanksgiving. Awesome car, awesome friends. I "tested" the secondaries several times.)

The small bore at 6:00 is the primary bore.