Jeep J-10 Series 1982 Technical & Service Manual page 404

1J-90 FUEL SYSTEMS
MICROPROCESSOR
TEMPERATURE
SENSOR
VACUUM
SWITCH
ASSEMBLY
OXYGEN
SENSOR
\
EMISSION
MAINTENANCE
SWITCH
81062A
Rg. 1J-156 C4 System
CAUTION: If trouble code51 was caused by thePROM
(Calibration Unit) being installed backwards, replace
ECM with another unit. Whenever the Calibration Unit
is installed backwards and the ignition switch is turned
on, the unit is destroyed.
Carburetor Model E2SE Idle Mixture Adjustment
The idle mixture is calibrated during factory assem
bly and should normally not need adjustment in the
field. However, if necessary because of results of C4
System diagnosis, contamination, overhaul, replace
ment of parts, etc., it can be adjusted according to the
procedureoutlined below. Becausethe C4 System is very
complex, the procedure must be followed precisely.
The dwell indication from the MC Solenoid is used for
the adjustment. During engine idle, it is normal for the
dwell to increase and decrease fairly consistently over a
relatively narrow range, such as 5 degrees. However, it
may occasionally vary by as much as 10 degrees to 15
degrees momentarily because of temporary abrupt mix
ture changes. The dwell specified in the procedure is the
average for the most consistent variation.
The engine must be allowed to stabilize at idle or 800
rpm, as applicable, before the dwell is acceptable as a
reference for adjustment.
NOTE: The mixture control solenoid dwell is an in
dication of the ratio of "on" to "off time (ie., solenoid
energized time-to-deenergized time ratio).
(1) If idle mixture plug has not been removed, re
move according to following procedure.
(a) Remove air cleaner and gasket.
WARNING: Battery negative cable must be removed
to prevent a potential fire hazard when fuel pipe is
disconnected.
(b) Disconnect battery negative cable.
(c) Disconnect fuel pipe and vacuum hoses from
carburetor. Identify and tag hoses.
(d) Disconnect throttle linkage and electrical
connectors.
(e) Remove carburetor attaching bolts and
nuts, and remove carburetor and mounting gasket.
(f) Invert carburetor and drain fuel in
container.
(g) Place inverted carburetor on suitable hold
ing fixture manifold side up.
CAUTION: Use care to avoid damaging linkage, tubes,
and parts protrudingfrom air horn.
(2) Remove idle mixture screw plug.
(a) Using a punch between two locator points in
throttle body beneath idle mixture screw plug (manifold
side) break out throttle body to gain access to idle mix
ture screw plug. Drive out hardened steel plug con
cealing mixture screw.
NOTE: Hardened plug will shatter rather than remain
ing intact. It is not necessary toremove plug completely;
instead, remove loosepieces to allow use ofIdle Mixture
Adjusting Tool J-29030.
(b) Lightly seat screw and back out 2-1/2 turns
for preliminary idle mixture adjustment. Final adjust
ment must be performed after carburetor is installed.
(c) If plug in air horn covering idle air bleed
screw has been removed, turn air bleed screw in until
lightly seated, then back out 1-1/4 turns. If plug is in
place, removal and adjustment is not required.
(3) Install carburetor on engine. Install battery
negative cable. Do not install air cleaner and gasket.
(4) Disconnect bowl vent hose at carburetor.
(5) Disconnect EGR valve and canister purge vac
uum hoses at carburetor and plug carburetor ports.
(6) Connect tachometer to distributor "tach" wire
connector located at vicinity of heater blower motor.
Connect dwell meter to mixture control solenoid dwell
test wire connector (fig. 1J-157).
(7) Place transmission in Neutral and set parking
brake.