57 

 

Engine ECU failure 

Oxygen sensor failure 

Intake pressure sensor failure 

Temperature sensor failure 

Electric controlling system failure 

Intake system leaking 

Idle speed stepping motor failure 

Throttle contains too much carbon deposit 

Improper throttle cable or thorttle position sensor adjustment

Idle speed over normal value 

Check 

Clean and replace 

Adjust 

Replace 

Clean 

Check 

Replace 

Replace 

Replace 

Leak 

Improper 

Over normal value 

Abnormal 

Abnormal 

Abnormal 

Abnormal 

Abnormal 

Abnormal 

Normal 

Normal 

Normal 

Normal 

Normal 

Normal 

Normal 

Normal 

 
 

 

 

58 

 

No. 033 Engine accelerates abnormal   

Malfunction Cause 

Solution 

Check air filter, whether it is blocked. Clean or replace when necessary. 

Air filter blocked 

Check intake system, whether it is leaking. Measure intake manifold vacuum, the 
value shall above 30kPa when idling. Otherwise, the intake system is leaking. Shall 
check connectors and all hoses and vacuum pipes carefully. 

Press accelerate pedal fully, and check whether the throttle fully opens. Adjust 
throttle cable or pedal, if it fails to open fully. 

Improper adjustment 
of throttle cable or 
throttle position 
sensor, which results 
throttle fail to fully 
open. 

Check throttle position sensor. During throttle varies from full close to full open, the 
resistance between signal terminal and earth terminal shall increase constantly, 
without interruption. Adjust or replace the sensor according to regulation, when 
abnormal. 

Improper ignition 
timing or weak spark 
energy. 

Check ignition timing. When idling, the ignition advance angle shall be 10º~12º. 
Otherwise, shall adjust the primary ignition advance angle. When accelerating, the 
angle shall increase to 20º~30º automatically. When abnormal, shall check ignition 
controlling system, including ignition coil, spark wire and spark plug etc., alternative 
replace ECU. 

Low fuel pressure 

Check fuel pressure. When idling, fuel pressure shall in accordance with regulation, 
265~304kPa. When accelerating, fuel pressure shall increase about 50kPa. If fuel 
pressure is too low, then shall check fuel pressure controller, electric fuel pump, fuel 
filter and etc. 

Injector blocked or 
poor atomization 

Remove injector and check injecting quantity and atomization quality, whether they 
are normal. When abnormal, clean or replace the injector. 

Low battery voltage 

Check battery voltage, whether it is normal. If the value is too low, when will cause 
fuel injecting quantity decrease, which results low engine power, as well as 
accelerating delay. In this case, shall check charging system or replace battery. 

Coolant temperature 
sensor malfunction 

Check coolant temperature sensor. In different temperatures, the resistance of the 
sensor shall vary in accordance with regulated standard. Otherwise, shall replace 
the sensor. 

Intake pressure 
sensor malfunction 

Check intake manifold pressure temperature sensor. Replace it when abnormal. 

Clutch sliding 

Replace driven plate of clutch. 

Low engine cylinder 
pressure 

Measure the compressing pressure of engine cylinder. If it is too low, then shall 
adjust valve clearance, or disassemble and inspect engine. 

Poor flywheel signal 

In case of low power and accelerating performance, caused by poor flywheel and 
signal wheel signal, shall replace flywheel assembly. 

Crankshaft position 
sensor malfunction 

In case of ECU order delay and low accelerating performance, caused by the sensor 
fails to indicate crankshaft position correctly, shall replace the sensor. 

Incorrect engine valve 
timing 

Check engine valve timing, whether it is correct. Adjust it when incorrect. 

Individual cylinder 
fails to work 

Check the operating condition of each cylinder, such as individual cylinder 
operating, whether it is abnormal. Particularly the spark plug, spark wire and cylinder 
pressure etc. Determine the malfunction cause and maintain or replace relating 
parts. 

Exhaust system 
blocked 

Check 3 way catalytic converter, whether it is blocked. The reverse interfere caused 
by blockage will result poor engine accelerating performance. In this case, replace 
3-way catalytic converter. 

Engine 
accelerates 
abnormal 

Oxygen sensor 
malfunction 

It results indiscernible mixture gas rate, as well as low power. 

 

 
 

 

 

59 

 

Oxygen sensor failure 

Exhaust system blocked 

Individual cylinder fails to work 

Incorrect engine valve timing 

Crankshaft position sensor failure 

Poor flywheel signal 

Low engine cylinder pressure 

Clutch sliding 

Intake pressure sensor failure 

Cooling fluid temperature sensor failure 

Low battery voltage 

Injector blocked 

Low fuel pressure 

Improper ignition timing or weak spark energy 

Air filter blocked 

Engine accelerates abnormal 

Improper adjustment of throttle cable or throttle position sensor 

Check 

Clean and replace 

Adjust 

Replace 

Clean 

Check 

Normal 

Replace 

Charge 

Replace 

Check 

Check 

Check and adjust 

Check 

Replace 

Check and replace 

Blocked 

Abnormal 

Abnormal 

Fails to work 

Abnormal 

Abnormal 

Error 

Poor 

Low 

Sliding 

Low 

Blocked 

Low 

Abnormal 

Blocked 

Improper adjusted 

Normal 

Normal 

Normal 

Normal 

Normal 

Normal 

Normal 

Normal 

Normal 

Normal 

Normal 

Normal 

Normal 

Normal 

Normal 

 
 

 

 

60 

 

No. 034 Water temperature over normal value   

Malfunction Cause 

Solution 

Lack of coolant 

Check cooling system, whether there is enough 
coolant. Add coolant if it is lack of coolant, which will 
affect cooling performance. 

Water temperature meter and sensor 

malfunction 

Water temperature over normal value, virtually. 
Replace relating components. 

Radiator leaking 

Check radiator cap and radiator, maintain or replace 
leaking part. 

Thermostat fails to open as normal 

Check upper and lower pipe temperature of radiator, 
if there is high value difference, then shall remove 
thermostat and measure the activating temperature. 
Replace thermostat if it fails to open normally.     

Water pipe leaking 

Check water pipe, maintain leaking position and 
fasten loose clip 

Check water pump driving belt, whether it is loose or 
damaged. Adjust or replace when necessary. 

Water pump malfunction 

Open radiator cap and start engine, to inspect 
coolant flowing condition and determine whether the 
water pump is working. If the coolant keeps still, then 
remove and check water pump. Replace it when 
blade wheel is damaged. 

Heater radiator leaking 

Check heater radiator, maintain or replace it. 

Check radiator cooling fan motor and fan blade, 
whether they are damaged. Maintain or replace them 
when necessary. 

Check coolant temperature sensor. In different 
temperatures, the resistance of coolant temperature 
sensor shall vary in accordance with regulated 
standard. Otherwise, shall replace the sensor. 

Radiator cooling fan fails to operate normally 

Check engine ECU and radiator cooling fan motor 
controlling circuit. Maintain or replace them when 
necessary. 

Cylinder head gasket damage 

Check radiator, whether there are bubbles nearby. 
Replace cylinder head gasket, may exclude the 
malfunction. 

Check radiator, whether it is blocked by mud or other 
impurity. Clean or replace it, when cooling 
performance is affected by blockage. 

Poor radiator cooling performance 

Check furring condition in radiator. Clean or replace 
it, when cooling performance is affected. 

Water temperature 

over normal value, 

when engine 

operating 

Part blockage in engine inner water cycling pipe Unplug or replace cylinder block