SC Decel Valve Question

[randyrap]

What exactly does the decel valve do and what can I expect if I were to remove or disconnect it?

Thanks ................................ Randy

[Hladun]

On rapid throttle release, holds rpm higher for a second or two before you go to idle rpm. If you take it out, engine may stall when you shift and/or come to a stop. You gain nothing but possible trouble if you take it out. In Martha's words "it's a good thing".

[echrisconnor]

Disconnecting/plugging will make your car return to idle faster. the downside is that sometimes the car will stall when you get off the throttle and push in the clutch

Plagiarized from the following site:


http://members.rennlist.com/jimwms/CIS/CIShome.html

(Also called Auxiliary Air device, or vacuum control.) When decelerating from high RPM with a closed throttle, this valve prevents high vacuum in the intake manifold by providing a path for air bypassing the closed throttle. This provides sufficient air in the air distribution box for a combustible mixture. It is one of three devices that bypasses air around the throttle plate. It opens with about 15 to 18 inches of intake manifold vacuum. Deceleration valve 0 280 160 111 pulls in at ~14" Vacuum. This component was supplied in two configurations on the CIS cars. The first type was on the early cars through the 79 models. It was mounted on the throttle body on the "firewall" side, pretty much out of sight. The second appeared on the '80 through '83 and can be seen on the right hand side of the engine, behind the fuel distributor.

The function of this device is the same for both configurations. For conditions of high intake manifold vacuum, such as when the throttle is abruptly closed, the valve opens, bypassing air around the throttle plate. This adds extra air to the mixture preventing a temporarily over-rich mixture. It opens at about 17 inches of vacuum, and closes again as the vacuum falls. In normal driving, (acceleration, and cruising) the valve remains closed.

In working an cars with the later model valve, I have frequently found the actuation line (small line) intentionally plugged by the owner or mechanic. The reasons for this escape me. I suppose that some drivers don't care for the slow fall in RPM caused by the operation of the valve when the accelerator is lifted at high RPM.

Failure mode: The diaphragm can leak, causing a too-high idle.

[beepbeep]

You get flames on decell

[randyrap]

Okay guys, you are going to like this one. I've already removed the decel valve from my engine thinking it was the Aux. Air Valve. (They sure look the same.LOL.) I did this a month or so ago.