Engine - Low Power/Poor Acceleration/Erratic Idle

91hyundai02

Group: Engine


Number: 026


Date: June, 1991


Model: Excel


Subject

CRANKSHAFT SPROCKET WEAR


Condition: Low power, poor acceleration, erratic idle.





Cause: The crankshaft is keyed to the crankshaft sprocket (timing belt sprocket) by means of flat areas on the sprocket. These flat areas may become worn and distorted allowing the crankshaft to rotate slightly in the crankshaft sprocket. This condition then gives the same effect as retarding the timing.


Diagnosis: On carbureted engines: Put a socket with breaker bar on the crankshaft sprocket bolt and try to rotate the crankshaft back and forth slightly. If the crankshaft feels like it has some freeplay and rotates slightly without moving the crankshaft pulley, the flats may be worn.

On MPI engines:
Check airflow sensor frequency and injector duration at idle with MUT. Normal readings should be about 40Hz and 2.8 to 3.3 ms duration. A worn crankshaft sprocket will cause these readings to be about twice as high.

Correction: Remove the crankshaft sprocket following procedure in shop manual. Inspect crankshaft sprocket and crankshaft mating surfaces. Replace as required.


PARTS INFORMATION


PART NAME CURRENT MODEL


23120-21000 '86 -'89 Excel
Crankshaft Sprocket

23120-24000 '90 - Excel


WARRANTY INFORMATION


OPERATION OPERATION MODEL MODEL OP TIME NATURE CAUSE
CODES YEAR CODES CODE

Replace Crankshaft 86-89 1.2 N13 C11
23122R00 Gear Sprocket Excel
90- 1.0