XY Powersports XY500UTV, Руководство по обслуживанию

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13. TROUBLESHOOTING
13-13
Errors coding: P2177
Self-learning value of air-fuel ratio, closed-loop control exceeds upper limit
Errors coding: P2178
Self-learning value of air-fuel ratio, closed-loop control exceeds lower limit
Introduction of theory and fault reason: In order to make catalytic converters for HC, CO and
NOx to maximize conversion efficiency, the air-fuel ratio of mixture should be 14.7:1. When
the engine occurs, parts manufacturing deviation, deposition of fuel colloid on fuel injector,
intake or back of valve, gas leak of intake and exhaust system, will cause the air-fuel
ratio(14.7:1) deviation in various degrees(partial dilute or partial concentration) which
will lead to emission deterioration and poor engine performance. Engine control system
will amend and self-learning fuel charge based on the extent and character is tics of air-fuel
ratio deviation. When self-learning value reach the limit of system setting (gas mixture
partial dilute or partial concentration, system amends the fuel charge constantly till Max),
system will judge that self-learning value transfinite fault.
Maintenance Tips
：
The possible faults may exists as follow:
1
） Injector clog needs cleaning
2
） Intake and exhaust system leaks
3
） Inlet or back of intake valve has carbon build-up, needs to be decarbonized.
4
） Engine parts deviation
5
） Valve clearance deviation
6
） Fuel system pressure deviation
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