Basic Engine Test - Jeep 1987 Wrangler Workshop Manual

ENGINES
IPS
FUEL FEEDBACK SYSTEMS
B A S I C ENGINE T E S T
IF THE RESULTS OF THE DIAGNOSTIC TESTS INDICATE THAT THE CEC SYSTEM IS
FUNCTIONING NORMALLY AND ENGINE PERFORMANCE REMAINS INADEQUATE
PERFORM THE FOLLOWING TEST
DETERMINE WHICH DIRECTION, RICH OR LEAN, THAT STEPPER MOTOR METERING PINS
CONSISTENTLY MOVE TOWARD.
YES
• INSPECT FOR AIR LEAKS AT INTAKE MANIFOLD
AND CARBURETOR GASKETS. INSPECT FOR FAULTY
VACUUM HOSES OR FITTINGS. REPAIR SOURCE
OF AIR LEAKS AND RETEST.
• CHECK FOR EXHAUST LEAKS AT OR NEAR 02
SENSOR. REPAIR AND RETEST.
IF METERING PINS VARY
CONSISTENTLY WITHIN
MIDRANGE, OPERATION IS
NORMAL. TEST COMPLETE
CHECK FOR FAULTY SPARK
PLUG(S); MISADJUSTED
IGNITION TIMING; AND
MALFUNCTIONING
IGNITION ADVANCE
MECHANISMS. REFER TO
GENERAL SERVICE AND
DIAGNOSIS SECTION
S E E
I.S.
N
O
T
E
S
ADJUST AND/OR REPLACE
COMPONENTS AS
NECESSARY. RETEST.
• CHECK CARBURETOR IDLE SPEED ADJUSTMENT AND CHOKE ADJUSTMENT. CHECK
OPERATION OF CHOKE LINKAGE. ENSURE HOSES AND WIRES ARE NOT INTERFERRING
WITH OR RESTRICTING CARBURETOR LINKAGE. REPAIR AS NECESSARY AND RETEST.
• INSPECT HEATED AIR TUBE FOR PROPER CONNECTION AT AIR CLEANER AND EXHAUST
MANIFOLD HEAT STOVE. REPAIR AS NECESSARY AND RETEST.
• INSPECT EGR VALVE FOR CORRECT INSTALLATION AND PROPER OPERATION. REPAIR AS
NECESSARY AND RETEST.
• INSPECT PCV VALVE FOR PROPER OPERATION. REPAIR AS NECESSARY AND RETEST.
• INSPECT VAPOR CANISTER FOR PROPER "PURGE" OPERATION AND CONDITION OF
HOSES. REPAIR AS NECESSARY AND RETEST.
81209
B-291