1976 FI system, deceleration valve
 

I am restoring a 1976 2.0 liter motor to put into a 1973 914 and trying to piece together FI parts. Does anybody know if a deceleration valve is required. If so what is the part number and where in the system does it go?
Thanks-

Required? That depends...

The engine will run without it. The only time you'll ever notice the lack is while you are decelerating with the throttle closed. The engine will probably burble and pop a bit without it. Also, when you are at medium or higher RPMs and then push the clutch in and let off the throttle completely, the decel valve can help keep the RPMs from dropping far enough for the engine to stall.

Early 1.7s did not have a DV.

I would install one, but I'm a believer in the EFI system.

It may or may not be required by your local smog laws. Even if required, it is unlikely that a tech will notice its lack.

I don't have a part number handy, but I'm sure Pelican can supply you with one if they're still being made.

It mounts to the upper bolt that also holds the Manifold Pressure Sensor bracket onto the right side of the engine bay. It has three vacuum hoses, two fat and one skinny. One of the fat ones and the skinny one both get hooked up to the manifold. The other fat hose gets hooked to the air cleaner. Check the hose diagrams available elsewhere on this very website for some drawings. (The 74 2.0 will be close, but might not be an exact match.)

--DD

Like DD says, it will work with it or without it. I suspect another effect of having a decel valve is that it decreases engine braking on closed throttle, so for a track car it may or may not be desirable.

The p/n is on my D-Jet parts web site, see the URL below. I think they're NLA, anyway.

My issues with the decel valve are:

1. What is the correct vacuum setting for it to open? Mine's been jiggered with so much that I have no idea. Does anyone have one that's never been adjusted that they could check?

2. How does the damn thing work, anyway? Don't kid yourself by simply applying vacuum with a hand pump to the skinny nipple end, sure the valve opens. But remember that in your car, the same vacuum is applied to the skinny nipple and to the port on the side of the decel valve, so there's no differential across the diaphragm, so it shouldn't open. And when I've simulated this on the bench, by applying vacuum to both ports, yep, it doesn't open.

Any answers or explanations are welcome.

Ignore this - I'm just seeing if I can make my web page link below active.

They are NLA and have seen two different versions. On my 75 its goldish and something like 4 inches across and has no adjustments. I have a second valve that I picked up somewhere that has a normal silver finish and is much smaller. The hoses are also a few sizes smaller which requires a little different plumbing. Will have to check to see if the PN is the same. Let me know if you need one, would be happy to sell you my spare. Just down the road from you in RB.

found it!
 

In the bottom of my parts box, I found the decel valve. I thought it was an (extra or different) fuel pressure regulator. Part number 0 280 160 108. Thanks again guys. That helps clear up my question about a couple of other manifold ports? Just a few more vacum ports to figure out.