77 280Z slow to idle down

[Ont240]

77 280Z 4 spd

Coming to an intersection, throttle off, the RPM is slow to idle down to normal (800 rpm) It's like the computer or something is telling it to wait 5 seconds or more before allowing the idle to drop to base.

Is there a cure or what is the fix?

thanks for any help.

[OldAndyAndTheSea]

Sounds like the BCDD

 

Boost Controlled Deceleration Device.

 

Search that, you'll find all you need to know.

[Tony D]

There is supposed to be a minimum of three seconds to drop down above 3000... Five sounds like a simple adjustment per FSM instructions.

 

This is an anti hydrocarbon emissions action. Snap throttle closing belches big gouts of unburned HC out the pipes, loading the catalyst bed which will make it heat up in stop-n-go traffic. It's still used today in the same way, save the computers are faster now so fuel-cut can take some of the load making it less noticable.

Edited April 15, 2012 by Tony D

[Ont240]

77 280Z 4 spd

Coming to an intersection, throttle off, the RPM is slow to idle down to normal (800 rpm) It's like the computer or something is telling it to wait 5 seconds or more before allowing the idle to drop to base.

Is there a cure or what is the fix?

thanks for any help.

 

I adjusted the BCDD by turning it clockwise (in) a bit, & test drove a few times after each adjustment.

Much better now

Thanks