Great Wall GW491QE, Руководство по обслуживанию

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EF.2-8 Delphi฀engine฀management฀systm-MT20U฀system฀control
13.฀Whole-vehicle฀exhaust฀control
¡¤ Whole-vehicle฀exhaust฀control฀means฀to฀precisely฀adjust฀the฀initial฀rating฀data฀of฀open-loop฀fuel฀within฀the฀vehicle฀traveling฀scope
allowed฀by฀exhaust฀laws฀and฀regulations,฀using฀a฀closed-loop฀control.฀In฀such฀way,฀the฀exhaust฀characteristics฀of฀vehicle฀may฀be
optimized.
¡¤ The฀closed-loop฀control฀system฀will฀play฀its฀role฀when฀oxygen฀sensor฀has฀been฀installed฀between฀the฀exhaust฀manifold฀and฀the
three-way฀catalytic฀converter฀to฀monitor฀the฀oxygen฀content฀in฀waste฀gas;฀The฀exhausted฀gas฀mixture฀containing฀thin฀oxygen฀content
may฀produce฀about฀100mV฀sensor฀voltage,฀while฀that฀containing฀thick฀oxygen฀content฀may฀produce฀about฀800mV฀sensor฀voltage.
When฀the฀air฀/fuel฀ratio฀is฀(14.6
£º 1),฀the฀sensor฀voltage฀may฀have฀an฀abrupt฀change.฀And฀the฀computer฀closed-loop฀control฀will
respond฀to฀the฀oxygen฀sensor฀signal฀to฀modify฀and฀control฀the฀variant฀so฀that฀the฀voltage฀of฀oxygen฀sensor฀could฀change฀within฀(100-
800)฀mV.฀In฀such฀way,฀an฀optimum฀air฀/fuel฀ratio฀may฀be฀controlled.
14.฀EOBD฀failure฀diagnosis฀&control
¡¤ EOBD฀is฀one฀much฀complicated฀self-diagnosis฀system฀used฀to฀check฀and฀test฀the฀failure฀on฀parts฀&components฀and฀systems฀which
will฀influence฀the฀vehicle฀exhaust.฀The฀OBD฀system฀does฀not฀take฀the฀place฀of฀regular฀exhaust฀test,฀and฀act฀as฀a฀monitor฀monitoring
the฀exhaust฀from฀vehicle฀on฀real฀time฀basis.
¡¤ Classification฀of฀EOBD฀diagnosis฀&test £º
-฀Parts฀&components฀test £º applicable฀to฀parts฀&components฀having฀input฀or฀output฀function฀on฀diagnosis฀instrument฀and฀controller;
The฀test฀is฀mainly฀performed฀in฀the฀electrical฀loop฀of฀parts฀&components,฀and฀it฀also฀includes฀determination฀on฀the฀reasonableness
of฀sensor฀input฀value
-฀System฀test
£º applicable฀to฀diagnosis฀on฀system฀failures,฀eg.฀misfire,฀deterioration฀of฀catalytic฀converter,฀failure฀with฀EGR฀control
system฀/cooling฀system,฀etc.฀The฀failure฀might฀result฀from฀mechanical฀parts฀or฀electrical฀loop.
-฀Controller฀(ECU)฀test
£º applicable฀to฀communication฀failure,฀hardware฀failure,฀RAM฀memory฀change,฀which฀correlates฀the
controller฀and฀the฀diagnosis฀instrument.
-฀Failure฀detection
£º Flash฀code฀function฀isn’t฀provided฀on฀the฀vehicle ¡£ The฀EOBD฀failure฀detection฀must฀pass฀a฀decoder฀and฀a
universal฀diagnosis฀interface.฀Any฀diagnosis฀instrument฀having฀EOBD฀function฀may฀be฀applied฀to฀any฀EOBD฀vehicle฀model.
¡¤ Missed฀fire฀diagnosis £º EOBD฀will฀detect฀any฀missed฀fire฀(on฀single฀cylinder฀or฀multiple฀cylinders)฀causing฀the฀abrupt฀change฀of
H C .
-Diagnostic฀method฀by฀the฀speed฀change฀of฀crankshaft
£º Any฀missed฀fire฀may฀be฀diagnosed฀by฀the฀speed฀change฀of฀crankshaft.
-Ionic-current฀diagnostic฀method £º Any฀missed฀fire฀may฀be฀diagnosed฀by฀observing฀the฀ionic฀current฀inside฀cylinder.
¡¤ Deterioration฀diagnosis฀on฀catalytic฀converter £º As฀required฀by฀EOBD,฀the฀indicator฀light฀shall฀be฀lighted฀and฀the฀faul t
code฀must be฀recorded฀when฀the฀deterioration฀of฀catalytic฀converter฀makes฀HC฀exceed฀the฀exhaust฀limit฀value
¡¤ Deterioration฀diagnosis฀on฀oxygen฀sensor £º The฀diagnosis฀on฀deterioration฀is฀only฀for฀upstream฀oxygen฀sensors.฀When฀oxygen
sensor฀becomes฀poisonous฀or฀is฀degraded฀in฀performance,฀the฀output฀will฀become฀slow.฀If฀so,฀the฀fault฀indicator฀light฀shall฀be฀lighted
and฀the฀fault฀code฀must฀be฀recorded.
¡¤ Deterioration฀diagnosis฀on฀waste-gas฀recycling฀system £º The฀waste-gas฀recycling฀system,฀when฀blocked฀by฀the฀carbide฀in฀waste
gas,฀loses฀its฀recycling฀function,฀which฀will฀result฀in฀an฀increment฀of฀Nox฀content.฀And฀the฀fault฀indicator฀light฀will฀be฀lighted,฀and฀the
fault฀code฀needs฀to฀be฀recorded฀accordingly.
¡¤ Failure฀diagnosis฀on฀idle-speed฀control฀system £º The฀failure฀on฀idle-speed฀control฀system฀will฀affect฀the฀performance฀and฀exhaust
of฀engine;฀The฀diagnosis฀may฀be฀performed฀by฀testing฀the฀actual฀rotating฀speed,฀and฀controlling฀its฀difference฀from฀the฀desired฀rotating
speed.
¡¤ ฀Deterioration฀diagnosis฀on฀fuel฀supply฀system £º The฀fuel฀supply฀system฀will฀gradually฀deviate฀from฀its฀original฀status฀due฀to฀the
aging฀and฀deterioration฀of฀hardware:฀A฀slight฀amount฀of฀deviation฀may฀be฀compensated฀by฀EMS฀control฀system;฀But฀when฀the฀extent
of฀deterioration฀is฀out฀of฀the฀self-adjustment฀limit฀by฀control฀system,฀the฀exhaust฀will฀be฀influenced.฀When฀the฀exhaust฀exceed s฀the
EOBD฀limit฀value,฀fault฀indicator฀light฀shall฀be฀lighted,฀and฀fault฀code฀must฀be฀recorded.
¡¤ Failure฀diagnosis฀on฀cooling-system £º Owing฀to฀the฀failure฀with฀water฀temperature฀sensor฀or฀temperature-saving฀valve,฀the
cooling฀system฀might฀make฀control฀system฀unable฀to฀enter฀the฀closed-loop฀control฀or฀have฀it฀postponed,฀which฀will฀affect฀the฀exhaust.
The฀diagnostic฀method฀is฀to฀forecast฀the฀change฀of฀water฀temperature฀by฀simulating฀the฀course฀of฀engine฀as฀to฀heat฀devices.
¡¤ Controller฀test £º Communication฀failure;฀RAM฀memory฀test;฀hardware฀failure,฀etc.
15.฀Program฀update฀function
ECU฀is฀available฀with฀such฀function฀as฀to฀online฀update฀the฀programs฀rapidly,฀and฀is฀able฀to฀update฀system฀control฀software฀directly
on฀vehicle฀yet฀without฀change฀of฀program฀chips.฀This฀function฀may฀be฀effected฀via฀serial฀input฀/output฀interface,฀and฀is฀easy฀to
operate.
The฀online฀updating฀of฀programs฀needs฀special฀software฀and฀shall฀be฀operated฀by฀Delphi฀specialist.
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