85 

 
No. 048 Exhaust pipe bombs   

Malfunction Causes 

Solution 

 

①

Improper ignition timing 

①

Check ignition timing. When the engine is at idling speed, 

ignition advance angle is 10°--12°; if not correct, adjust 
advance angle of initial ignition of the engine. When 
accelerating, ignition advance angle could automatically be 
increased to 20°--30°. If unusual, check ignition control system 
or replace ECU; 

②

Oil injector leaking, causing gas mixture 

too thick 

②

Check oil injector is leaking; if so, replace it;   

③

Engine valve timing error 

③

Check valve timing is correct; if not, adjust it; 

Exhaust pipe 
bombs 

④

Oil injection control program malfunction 

within ECU 

④

Replace engine’s Electronically Controlled Unit (ECU); 

 

 

Repair 

Exhaust pipe bombs 

Improper ignition timing 

Oil injector leaking 

Engine valve timing error 

Clean 

Repair 

Oil ejection control program malfunction 

Replace 

Normal 

Unusual 

Normal 

Normal 

Improper 

Leaking 

Error 

 
 

 

 

86 

 
No. 049 Engine knocking   

Malfunction Causes 

Solution 

Fuel with low grade and poor quality   

Check fuel quality and confirm fuel grade; if not reaching 
specified requirements, replace it;   

Ignition time too early   

Check ignition timing. When the engine is at idling speed, 
ignition advance angle is 10°--12°; if not correct, adjust 
advance angle of initial ignition of the engine. When 
accelerating, ignition advance angle could automatically be 
increased to 20°--30°. If unusual, check ignition control system 
or replace ECU; 

Cooling system malfunction   

Engine overheating may cause this problem; check cooling 
system;  

Put screwdriver at filler port, and put your ear against the 
screwdriver lever, and carefully observe and listen;   

Flame out for cylinders gradually; if sound of this cylinder 
weakens or disappears, then it is confirmed that this cylinder 
has abnormal sound;   

To differentiate from other abnormal sound, fill in some 
lubricating oil at spark plug hole of this cylinder; if the sound 
weakens or disappears, then it is confirmed as piston knocking 
sound;  

When knocking sound is very severe and filler port is smoking 
externally, it is because that clearance between piston and 
cylinder wall is too large; 

Piston and cylinder wall severely worn, 
with too large clearance 

After confirming knocking sound, check cylinder diameter and 
piston dimension; repair according to technical requirements or 
replace it;   

Intake manifold leaking   

Causing too many intake amounts, and thin gas mixture 
causes engine knocking; check pipes; if abnormal, repair or 
replace;  

Oil pressure too low   

Oil pressure too low, causing too few ejecting amounts, and 
thin gas mixture causes engine knocking; check fuel pump and 
pipe; if necessary, replace it;   

Oil injector blocked   

Oil injector blocked, causing too few ejecting amounts, and thin 
gas mixture causes engine knocking; check and clean the oil 
injector; if necessary, replace it; 

Carbon deposit within the cylinder too 
many 

Check carbon deposit within the cylinder; if too many causing 
glowing ignition and knocking, clean it; 

Compression rate too large   

Check cylinder cover is grinding; if grinding too large causing 
combustion chamber smaller, and compression ratio too large 
causing piston knocking, replace cylinder cover; 

Individual cylinders not working   

Eliminate it one by one   

Intake manifold pressure temperature 
sensor invalid   

Causing too many intake amounts, and thin gas mixture 
causing engine knocking; check electrical signal of sensor; if 
abnormal, replace it;   

Metal knocking sound 
occurs when the 
engine increases the 
load or grades up 

Program malfunction within ECU   

Replace ECU assembly;   

 

 
 

 

 

87 

 

Repair 

Carbon deposit within the 
cylinder too many 

Compression rate too large 

Individual cylinders not 
working 

Intake manifold pressure temperature sensor 
invalid 

Oil ejector blocked 

Oil pressure too low 

Piston and cylinder wall severely worn, with too large clearance 

Ignition time too early 

Fuel with low grade and poor quality

Engine knocking 

Replace 

Clean 

Repair 

Repair 

Repair 

Repair 

Repair 

Replace 

Intake manifold leaking 

Cooling system 
malfunction 

Repair 

Repair 

Program malfunction within 
ECU 

Replace 

Normal 

Poor quality

Normal 

Normal 

Normal 

Normal 

Normal 

Normal 

Normal 

Normal 

Normal 

Normal 

Worn

Too early

Too low

blocked

Too much 

Too large

Not working

Abnormal

Leaking

Abnormal

Abnormal

 
 

 

 

88 

 
No. 050 Engine burning oil   

Malfunction Causes 

Solution 

PCV valve invalid   

Check one-way throughout of PCV valve at upper of valve chamber 
hood; if not, it will cause exhaust gas pressure too high within the 
engine, thus burning engine oil; otherwise replace it;   

Engine oil too much   

Reduce oil amounts;   

Engine oil with poor quality   

Replace engine oil;   

Check valve oil seal is aged, without sealing, engine oil enters to 
combustion chamber through valve stem. Replace valve oil seal;   

Valve oil seal malfunction   

Check clearance between valve stem and valve guide; if too large 
caused by abrasion, replace it;   

Valve oil seal malfunction   

Check piston ring is broken and elasticity and end clearance, side 
clearance, back clearance conform to requirements; if not, replace;   

Oil consumption 
too much, tail gas 
in blue 

Piston and cylinder severely worn

Check clearance between piston and cylinder bushing conforms to 
requirements; if not, repair the engine; 

 

Replace 

Repair 

Engine burning oil 

PCV valve invalid 

Valve oil seal malfunction 

Engine oil too much 

Engine oil with 
poor quality 

Piston ring, piston and 
cylinder malfunction 

Repair 

Replace 

Discharge 

Normal 

Abnormal

Normal 

Normal 

Normal 

Invalid 

Abnormal

Too much 

Poor