Having a funny idle problem? Already did a normal tune up
with fresh spark plugs, PCV, fuel filter, cap/rotor and maybe even new spark
plug wires? Did you run a code scanner and got nothing? It is time to clean
the idle control valve.
Depending on whom you talk to, this little gadget is called the ISC, BYP, IAB
or IAC valve. Whatever you call it, the valve goes bad due to a broken motor
or soot buildup from crankcase vapors. The answer is to clean the assembly
or, if all else fails, replace the motor attached to the unit with a fresh
one.
Where is it?
On EEC-IV multi-port EFI motors, the idle control valve is located on the throttlebody.
The valve has a cylindrical shape with a small wiring harness at one end, with
another casting that attaches to the throttlebody.
For the 1986-up Mark VII and Continental, the valve is located on the throttlebody
facing you. (see picture above) On the 1986-90 Town Cars, the valve is in the
same area, but not facing you. For 1997-98 Mark VIII's, the valve is visible
on the intake. For 1993-96 Mark VIII's and 1995-2002 Continentals, it is near
the throttlebody. On Mark VIII's, this is nestled DEEP inside the intake near
the firewall.
Valve location on 1995-2002 Continental, and 1993-1996 Mark VIII
Now what?
There are two 5/16th bolts holding the valve to the throttlebody. Disconnect
the harness with a small flathead screwdriver and unbolt the valve. Check the
gasket that attaches the valve to the throttlebody for any damage or cracks,
and replace if necessary.
With the valve in your hand, generously spray light oil such as WD-40, or a
throttlebody/carb cleaner in the two bores of the valve. Shake the valve around
to ensure the cleaner is moving freely in the bore. If possible, get a length
of fuzzy pipe cleaner and use it to scrub the bores to a shine.
Shake the valve until most of the fluid is expelled. Repeat the above procedure
if the expelled fluid is extremely dirty. Reattach the gasket, the valve and
its wiring harness. You should see a dramatic difference in the idle control
of the car.
That didn’t fix it, so now what?
Check the wiring harness for damage and use a test light or voltmeter to check
for power to the valve. Lastly, make sure the harness has a clean connection
to the valve. When all else fails, replace the motor with a working one (for
those of you with more than one EEC-IV or V controlled car) or buy one from
a parts store/junkyard. The motor is a separate part that disconnects to the
valve with two screws.
Possible EEC codes generated by a bad valve:
1980's and early 1990's Lincoln 2- digit codes: 12, 13, 16, 17
1990's to present 3- digit codes: 411, 412, 415, 416 and 551
