82 prelude high-idle

Hi all,

The idle speed on my 82 prelude has suddenly increased from 1000 rpm
to ~2000 rpm. Even after the car has warmed up it settles to about
1800-2000 rpm on idling.

On a couple of occasions it did seem to come back to its idle speed of
1000 rpm, but it doesnt seem to hold it there for a sustainable amount
of time.

I have also noticed that when I change gears, and I press the clutch,
the RPM momentarily shoots up to 3000 and then comes down again. It is
a carbureted car. I checked with a mechanic verbally and he thought my
carburetor is going bad. But I am not sure if this is indeed the
problem because I havent seen other signs. I get decent gas mileage
(28-30 mpg)

So, I am not sure what could be wrong. Any thoughts would be much
appreciated.


Sincerely,
Sunny

 

for idle problems i would suggest first, check for intake vacuum
leaks, and make sure the PCV valve is working properly

then if the idle problem persists but only when the engine is cold,
it's ignition

but if the idle problem persists even when the egine is warm, it's the
fuel system

since you get good mileage, i think the carb's choke didn't get stuck
closed. In fact, i think your carb is fine.

and that the idle races up and comes down indicates a major vacuum
leak, most likely a stuck open PCV valve. You won't be able to tell if
a PCV valve is stuck open when driving, it's supposed to be open on
moderate and wide open throttle anyways. But the problem is pronounced
when the throtle plate is closed