Geely JL481Q, Руководство пользователя, Страница: 169 / 198

III. Oil and Circuit Faults that Reduce Engine Performance
Poor engine performance mainly appear as insufficient power, poor acceleration, larger fuel consumption, poor idle speed
and overheating of engine etc.
1. Insufficient Power
(1) Symptom of fault:
The engine is basically normal when operates without load, but acceleration is slow when it runs with load, powerless when
it climbs a slope, even if the throttle valve is treaded down to the end, power is still insufficient, speed cannot be increased
and cannot reach max. speed.
(2) Cause of fault:
a. Clogged air filter;
b. Poor airtightness of intake system;
c. Intake pressure sensor failure;
d. Insufficient fuel pressure;
e. Cracked pressure adjuster;
f. Blocked injector or poor atomization;
g. Throttle position sensor failure;
h. High voltage spark too weak;
i. Improper throttle spacing;
j. Poor airtightness of intake, exhaust valve, ineffective piston ring, low compression pressure;
k. Excessive carbon accumulation in spark plug and combustion chamber;
l. Water temperature switch or thermostat fails;
m. Oxygen sensor(EGO) aging;
n. Ignition timing incorrect;
o. Check valve fails;
(3) Diagnosis procedure of less powerful engine (Fig. 357)
2. Poor Deceleration
(1) Symptom of fault:
Idle operation is normal, but when loosening accelerator pedal abruptly during driving for
deceleration, engine flameout often occurs.
(2) Cause of fault and elimination method
a. Throttle position sensor is damaged, replace it;
b. Original idle speed is not adjusted properly or automatic control of idle speed is abnormal,
readjust or repair it;
c. Fuel cutoff control is abnormal, fuel cutoff speed is too low, ECU fails, repair or replace it;
3. Poor Acceleration
(1) Symptom of fault
After accelerator pedal is treaded, engine speed does not rise immediately, there is hysteresis, acceleration response is
slow, or there is slight fluctuation in the process of acceleration.
(2) Cause of fault and troubleshooting
a. Throttle position sensor is defective, repair, eliminate or replace;
b. Poor airtightness of intake system, repair and eliminate;
c. Low fuel pressure, check and eliminate
d. Injector works poorly, check, clean or replace it;
165