Brief high idle

[siteunseen]

When I push in the clutch at Stop Signs or Red Lights or any other time I'm about to stop my '77 stays between 2,000 & 2,500 RPM for about 5 seconds then falls down to normal idle. Any advice as to what it could be? Opened Throttle Switch, black box on manifold, looked like new. Air sprayed the dust and cleaned the plug-in with electrical cleaner then Dielectic grease. Still does it. So I think extra fuel is burning off but I don't know squat. Help.

[sblake01]

Check your BCDD. If it's a California car, also check the altitude switch.

[mgood]

That's normal, it's a from of an anti stall device. It's was designed to help with down shifts. Others will tell you the technical name and reason, so not a problem.

[sblake01]

Neither my 78 280Z or my 79 810 ever did that except when there was a problem with either the aforementioned items in post #2. The dashpot, which basically keeps the throttle from closing abruptly when you let off the pedal, was the anti stall device.

[240260280z]

I had same problem with bccd. Just turn it a few turns one way and test. If the idle decreases too quickly at a stop or if it stays high for longer then turn the otherway.

The bccd is under the throttle body and there is either a screw or a nut to turn.

[LeonV]

They are not "anti-stall" devices. If your car stalls without a throttle dashpot, then something is wrong. The reason for these devices is to keep the throttle slightly open on abrupt closures in order to keep hydrocarbon emissions down, i.e. it creates less unburned fuel.

[siteunseen]

The BCDD is exactly what it was. Tightened the nut and it went to normal idle. Thank you. Y'all could cure cancer.