Decel Valve

lochrie2 · lochrie2's Garage

I noticed today that I have no hose on the decal valve. what does it connect to? the car runs great but I do get some exhaust popping on decal not sure if this is the cause. I am also running the car without the o2 sensor

ClickClickBoom · ClickClickBoom's Garage

Quote:

Originally Posted by lochrie2

I noticed today that I have no hose on the decal valve. what does it connect to? the car runs great but I do get some exhaust popping on decal not sure if this is the cause. I am also running the car without the o2 sensor

The ‘82 Yugo?

lochrie2 · lochrie2's Garage

The car is an 80 SC

watmough · watmough's Garage

Yeah, mine (82 sc) has this same nipple disconnected (by me), as when connected to the vacuum source, it'll both hold at highish revs, and increase a normal idle to about 2000 rpm. Feathering the clutch works to lower the idle, but it can increase at will, which is painful in traffic.

The wisdom runs that these valves are pretty much wrong from the factory, and should only bypass air to slow rev drop at 18 mmHG (units?) vac, but actually will bypass air at more like 16 - 17 mmHg.

Disconnecting allows your revs to drop fast, mine drop very fast to 1200 or so, then slower to 950, with some popping when driving when coming off-throttle. And there was no popping before I disconnected mine, so I'd tend to blame this.

tirwin · tirwin's Garage

exhaust burble is a symptom disconnected decel valve. mine does. I kinda like it.

boyt911sc · boyt911sc's Garage

Quote:

Originally Posted by watmough

Yeah, mine (82 sc) has this same nipple disconnected (by me), as when connected to the vacuum source, it'll both hold at highish revs, and increase a normal idle to about 2000 rpm. Feathering the clutch works to lower the idle, but it can increase at will, which is painful in traffic.

The wisdom runs that these valves are pretty much wrong from the factory, and should only bypass air to slow rev drop at 18 mmHG (units?) vac, but actually will bypass air at more like 16 - 17 mmHg.

Disconnecting allows your revs to drop fast, mine drop very fast to 1200 or so, then slower to 950, with some popping when driving when coming off-throttle. And there was no popping before I disconnected mine, so I'd tend to blame this.

Watmough,

Found some decel valves to open at 22 in. Hg during tests and the good ones are closed @ 16 inch Hg. The most common problem with the decel valve is the inability to keep closed during operation well below 16 inch Hg.

Tony