DIY_EFI Digest V1 #64

[lowell at smartt.com]

>From: CHAN WEN YEN <chanwe at ecf.toronto.edu>
>Date: Sun, 3 Mar 1996 12:16:27 -0500
>Subject: rough idle -- help
>
>I'm repairing a 1990 Acura Integra with the 1.8 l engine (no MAF sensor)
>. The engine has a rough idle when the ambient air temperature is below
>zero and the engine is warm. The idle will dip as low as 500 RPM when the
>brake is applied (the car is not automatic) and will eventually settle
>just below the normal idle (normal idle - 750). The idle will also
>fluctuate +/- 50 RPM @ idle. During periods of rough idling the 
>vacuum fluctuates rapidly +/- 1/4 inHG about 19 inHG.
>
>	I have changed the air and fuel filters, the spark plugs, the
>distributor cap, the PCV valve, reset the base idle & advance, set the
>valve lash, removed the carbon from the intake manifold, throttle plate
>& valves and used about 4 doses of fuel injector cleaner (motormaster
>brand). After changing the air & fuel filters the idle was smooth &
>stable for about 5 min.

Watch the voltage at the EACV (idle valve) or try pinching the hose to it.
If the idle stops bouncing around, it could be sticky, or the ECU is being
fooled somehow.  Take the valve off and turn the key from off too accessory.
It should open fully and close fully when the key is turned off.  Things
that affect EACV voltage would be: electric load detector, coolant temp
sensor, throttle position, rpm, basicaly lots to look at.  Try and get a
factory shop manual for a good explanation of how it all works.