Chery A15. Manual - part 273

 

Troubleshooting Flowchart 

 
Troubleshooting procedure 

Troubleshooting structure 

Driver introduction 

Diagnosis location 

Appearance checking and relevant 
checking 

Defected engine model 

Master faults 

Fault description 

Basic tests 

Running status 

Check relevant system and equipment 

Diagnosis description 

Partial diagnosis 

Fault description 

Warranty adjustment 

Maintenance description 

Completion inspection 

Driver feedback 

Driver feedback 

 

 
 
 
Three. Diagnosis parameters 
1. Temperature and temperature change rate 
Determine the engine fault mode and location by temperature and temperature change 
rate. 
Diagnostic scope: 
A. Combustion status of media inside the engine combustion chamber; 
B. Working status of the cooling system and lubrication system;  
C. Engagement between clutch brake pad and pressure plate and the working status of the 
transmission gear, etc;  
D. Overcurrent status of electrical components and wires;  
2. Pressure 
Determine engine fault modes and locations by pressure.  
Diagnostic scope: 
A. The sealing between the engine throttle and throttle seat ring or between the 
piston/piston ring and cylinder wall can be judged by the compression pressure of the 
cylinder.  
B. The working status of the lubrication system and the lubricating clearance may be 
judged by the engine oil pressure;  
 
 
 
 
 
 
 
 
 
 
 

 

C. Determine the sealing of the cooling system by the cooling fluid;  
D. Determine the ratio of fuel and gasoline by the fuel supply system pressure.  
3. Vacuum 
Determine the engine’s technical status by the vacuum conditions.  
Diagnostic scope:  
A. Wear and tear conditions of cylinder 
B. Sealing of air dosing mechanism; 
C. Leakage of air intake system 
4. Crank case air leakage 
Judge the engine fault mode and engine performance by the crank case air leakage or the 
gas pressure in the crank case. 
A. Technical status of engagement between engine piston, piston ring and cylinder wall 
(cylinder wall wear, cylinder hole deformation, piston deformation and if piston ring is 
properly fixed, etc); 
B. Determine engine power by crank case air leakage;  
C. Determine pollutant emission by the engine by crank case air leakage;  
D. Measure engine oil consumption. 
5. Turning speed and turning speed change rate 
Diagnosing engine fault modes and performance by measuring engine speed or speed 
change rate. 
A. Diagnose engine’s abnormal noise by engine speed or engine speed change rate; 
B. Judge engine power by measuring engine speed or speed change rate; 
C. Judge working status and fault location of the ignition system.  
6. Vibration, vibration frequency and amplitude 
Evaluate the engine’s technical status and the processing of engine running mechanism 
by engine vibration and vibration parameters to determine the engine’s assembly quality.  
A. Determine the working status of engine ignition system by engine vibration (e.g. spark 
plug short circuit, open circuit and short circuit of high-voltage circuit, short circuit and 
breakdown of ignition coil, etc); 
B. Determine the fixing status of gear belts by its frequency; 
C. Engine engagement clearance;  
D. Working status of spray nozzle; 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 

7. Abnormal noise 
Determine engine faults and evaluate engine manufacturing quality by its noise 
characteristic, frequency and location. 
A. Cooperation between different mechanisms of the engine; 
B. Lubrication system status; 
C. Knock combustion and working status of the engine.  
8. Fuel composition analysis 
Analyze the chemical process that causes the engine faults on the basis of physical and 
chemical tests of fuel ingredients to determine engine faults.  
A. Low octane rating of fuel and poor anti-knock property result in engine knock 
combustion and consequently abnormal noise, or even burned cylinder cover, piston head 
and cylinder gaskets as well as broken piston ring.  
B. Too low viscosity of engine oil results in low engine oil pressure so that oil film 
intensity on friction pairs can’t be guaranteed and therefore burned shaft bushing and 
early wear are resulted; 
C. Too high engine oil viscosity results in high engine oil flow resistance, high power 
consumption and even air leakage in severe cases (i.e. air leakage at the filter due to slow 
flow of engine oil) so that there is an insufficient supply of engine oil and therefore early 
wear, burned shaft bushing and other faults are caused.  
D. High gelatine content in the fuel will easily result in charcoal accumulation, knock 
combustion, surface ignition and finally engine damage; the gelatine will block the 
lubrication circuit and lock the piston ring, spray nozzle piston and engine oil relief valve 
and finally engine faults.  
9. Voltage, current and resistance 
Determine fault modes and locations of electrical components by measuring these 
parameters.  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 

Section Three. Basic Checking of the Engine 

 
One. Daily operation and maintenance 
1. Fuel and lubrication oil  
93# leadless gasoline or above must be used for the engine. 
The content of lead and other heavy metals of leadless gasoline must satisfy current state 
criteria. The lead and other heavy metals in the fuel will permanently disable the oxygen 
sensor and three-way catalyst.  
The sulfur content in the fuel shall also satisfy the state criteria. Sulfur will disable the 
oxygen sensor and three-way catalyst as well. In the case of sulfur infection, run the car 
at a speed of 70km/h for ten minutes to reduce the harm caused by sulfur. Gasoline with 
relatively high sulfur content has a deeper brown color than usual.  
Engine’s oil consumption shall remain at a certain level. If engine oil goes into the 
cylinder and gets combusted, the phosphor in the engine oil will permanently disable the 
oxygen sensor and three-way catalyst.  
2. Daily operation and maintenance 
During long-term storage, the engine or vehicle shall be started once every month to 
avoid gelation at spray nozzles and fuel pump;  
Replace the gasoline filter once the vehicle has driven a distance of 7,000 – 10,000km; 
under normal running conditions, clean the throttle body and spray nozzles once every 
year or every 20,000km. If the spray nozzles are cleaned without being unfixed, it shall 
be made sure that the additives do not contain any substances harmful to the oxygen 
sensor and three-way catalyst;  
During double-idle-speed exhaust checking, make sure that the engine and three-way 
catalyst have been fully warmed up. Execute high-idle-speed measurement first and then 
low-idle-speed measurement.  
Proposals for warming up the engine and catalyst: 
Run the vehicle at third-gear and at a speed of 70km/h for over 5 minutes and check the 
exhaust within 8 minutes; 
Slightly step on the accelerator pedal and idle run the engine at a speed of over 4500rpm 
for over 2 minutes. Check the exhaust within 2 minutes.  
Warm air water tank: 
In some cold regions, bigger or additional warm air water tanks are installed on vehicles, 
which shall be approved by the Company because excessive warming up will result in 
under temperature of the engine cooling fluid and thus increase engine wear, fuel 
consumption and accumulated charcoal in the engine and exhaust system;