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;