Noticed recent problem with high idle after warm-up. Checked throttle, it was closing completely. Two other suspects high on the list were AAR and decel valve. Clamped hose from decel valve to plenum, idle dropped to normal, AHA culprit found. Anybody else have any problems like this? Is this indicative of a bad valve? I know most people have done away with the decel valve and plugged the lines.

Thanks

With the car off, you should not be able to blow/suck air through either of the large orifices. If it's not closing when the car is off, it's busted. If it IS closing, then you have enough vacuum at idle to open the valve.

Yes, you have a bad decel valve.

--DD

Here's another question. If you have the connections from the decel valve to the plenum and the air filter housing backwards, what does the valve do? Do you have an open valve at idle(vacuum leak condition=high idle) or does the valve do nothing. Without checking the valve, I switched the hoses from the plenum and the air filter housing and, voila!, idle has dropped. Did I fix the problem, or is the valve just doing nothing at this point?

I'd definately just get rid of the decel valve. It's not necessary, and the car drives better without it. I hate the hanging RPMs that happen on cars with decel valves on it.

If you're talking about the larger-diameter hoses, then you can hook them up either way. I believe if you hook the smaller-diameter hose to the air cleaner, it will simply never open.

--DD

the D-Jet one is adjustable BTW.

the L-Jet version needs the hose connected to the plenum, while the two big hoses connect elsewhere.