165 

No.123 Normal startup, idling speed is instable or the vehicle will flame 

out when partially loaded (such as: when air conditioner is on)   

General malfunction part: 1. air conditioning system; 2、idling speed regulator; 3. oil injector. 
General diagnosis flowchart: 

Serial 
No. 

Operation steps 

Results  

Follow-ups  

Yes 

Clean concerned 
parts 

1 

Remove idling speed regulator, and check throttle valve body, idling speed 
regulator and idling speed bypass air duct are with carbon deposit. 

No Next 

step 

Yes 

To step 4 

2 

Observe output power of the engine is increased while air conditioner is on, i.e. 
observe changes of ignition advance angle, oil injection pulse width and air input 
with diagnosis instrument of electric injection system. 

No Next 

step 

Yes Next 

step 

3 

Connect commutator of electric injection system, and disconnect connecting line of 
75# pin of electronic control unit. Check there is high level signal at harness end 
when air conditioner is on. 

No 

Repair air 
conditioning 
system  

Yes Next 

step 

4 

Check pressure of air conditioning system, electromagnetic clutch of air 
compressor and AC compression pump are normal. 

No 

Repair air 
conditioning 
system 

Yes 

Replace 
malfunction ones 

5 

Remove oil injector, and check it is leaking or blocked, or flow with out of tolerance 
with special cleaning and analysis instrument. 

No Next 

step 

Yes Diagnosis 

help 

6 

Connect commutator of electric injection system, and open ignition switch, and 
check power supply of 12#, 13#, 44#,    45#, ,63# pins are normal; check bonding 
of 3#, 51#, 53#, 61#, 80# pins are normal. 

No 

Repair 
corresponding lines

 

 
 

 

 

166 

No.124 Normal startup, the idling speed is too high   

General malfunction part: 1. throttle valve body and idling speed bypass air duct; 2. vacuum pipe; 
3. idling speed regulator; 4. cooling liquid temperature sensor; 5. ignition timing. 
General diagnosis flowchart: 

Serial No.  Operation steps 

Results   

Follow-ups   

Yes Adjust 

 

1 

Check throttle cable is jammed or too tightening.   

No Next 

step 

Yes 

Repair air intake 
system 

2 

Check vacuum pipe of intake system and connection is leaking. 

No Next 

step 

Yes 

Clean concerned parts

3 

Remove idling speed regulator, and check throttle valve body, idling 
speed regulator and idling speed bypass air duct are with carbon deposit.

No Next 

step 

Yes 

Repair lines or replace 
sensor 

4 

Take out connector of cooling liquid temperature sensor, start the engine 
and observe the engine's idling speed is too high at this time.   

No Next 

step 

Yes Next 

step 

5 

Check ignition timing of the engine conforms to the specification.   

No Repair 

ignition 

timing 

Yes Diagnosis 

help 

6 

Connect commutator of electric injection system, and open ignition switch, 
and check power supply of 12#, 13#, 44#,  45#, ,63# pins are normal; 
check bonding of 3#, 51#, 53#, 61#, 80# pins are normal. 

No 

Repair corresponding 
lines 

 

 
 

 

 

167 

No.125 Unable to rotating speed or flameout while accelerating   

General malfunction part:1. fuel containing water; 2. intake pressure sensor and throttle valve 
position sensor; 3. spark plug; 4. throttle valve body and idling speed bypass air duct; 5.intake 
duct; 6. idling speed regulator; 7. oil injector; 8. ignition timing; 9. exhaust pipe. General 
diagnosis flowchart: 

Serial No.  Operation steps 

Results   

Follow-ups   

Yes 

Repair air intake system

1 

Check air filter is blocked. 

No Next 

step 

Yes Next 

step 

2 

Connect fuel pressure gauge (access point is front end of oil sucker of 
fuel distribution pipe assembly), and start the engine, and check fuel 
pressure is around 350kPa during accelerating. 

No 

Repair oil supply system

Yes Next 

step 

3 

Check spark plug of each cylinder, and observe its type and clearance 
conform to the specifications. 

No 

Adjust or replace 

Yes 

Clean concerned parts 

4 

Remove idling speed regulator, and check throttle valve body, idling 
speed regulator and idling speed bypass air duct are with carbon deposit.

No Next 

step 

Yes Next 

step 

5 

Check intake pressure sensor, throttle valve position sensor and its lines 
are normal.   

No 

Repair lines or replace 
sensor 

Yes 

Replace malfunction 
ones 

6 

Remove oil injector, and check it is leaking or blocked with special 
cleaning and analysis instrument. 

No Next 

step 

Yes Replace 

fuel 

7 

Check fuel condition and observe malfunction is caused just after 
refueling.  

No Next 

step 

Yes Next 

step 

8 

Check ignotion sequence and ignition timing of the engine conform to the 
specifications. 

No Repair 

ignition 

timing 

Yes Next 

step 

9 

Check exhaust pipe is smoothly exhausted. 

No 

Repair or replace 
exhaust pipe 

Yes Diagnosis 

help 

10 

Connect commutator of electric injection system, and open ignition 
switch, and check power supply of 12#, 13#, 44#,  45#, ,63# pins are 
normal; check bonding of 3#, 51#, 53#, 61#, 80# pins are normal. 

No 

Repair corresponding 
lines 

 
 

 

 

168 

No.126 Slow reaction while accelerating 

General malfunction part:1. fuel containing water; 2. intake pressure sensor and throttle valve 
position sensor; 3. spark plug;4. throttle valve body and idling speed bypass air duct; 5.intake 
duct;6. idling speed regulator; 7. oil injector; 8. ignition timing; 9. exhaust pipe. General diagnosis 
flowchart: 

Serial No.  Operation steps 

Results   

Follow-ups   

Yes 

Repair air intake 
system 

1 

Check air filter is blocked. 

No Next 

step 

Yes Next 

step 

2 

Connect fuel pressure gauge (access point is front end of oil sucker of 
fuel distribution pipe assembly), and start the engine, and check fuel 
pressure is around 350kPa during accelerating. 

No 

Repair oil supply 
system 

Yes Next 

step 

3 

Check spark plug of each cylinder, and observe its type and clearance 
conform to the specifications. 

No 

Adjust or replace 

Yes 

Clean concerned parts

4 

Remove idling speed regulator, and check throttle valve body, idling 
speed regulator and idling speed bypass air duct are with carbon deposit.

No Next 

step 

Yes Next 

step 

5 

Check intake pressure sensor, throttle valve position sensor and its lines 
are normal.   

No 

Repair lines or replace 
sensor 

Yes 

Replace malfunction 
ones 

6 

Remove oil injector, and check it is leaking or blocked with special 
cleaning and analysis instrument. 

No Next 

step 

Yes Replace 

fuel 

7 

Check fuel condition and observe malfunction is caused just after 
refueling.  

No Next 

step 

Yes Next 

step 

8 

Check ignition sequence and ignition timing of the engine conform to the 
specifications. 

No Repair 

ignition 

timing 

Yes Next 

step 

9 

Check exhaust pipe is smoothly exhausted.   

No 

Repair or replace 
exhaust pipe 

Yes Diagnosis 

help 

10 

Connect commutator of electric injection system, and open ignition 
switch, and check power supply of 12#, 13#, 44#,  45#, ,63# pins are 
normal; check bonding of 3#, 51#, 53#, 61#, 80# pins are normal. 

No 

Repair corresponding 
lines