Great Wall GW491QE, Service Manual

Page: 39 / 222

EF.1-20
United฀Electronic฀engine฀management฀system-Analysis฀of฀function฀/principal฀/
failure฀for฀system฀parts฀&components
9.฀ Idle-speed฀ adjustor฀ EWD3 M 1.5.4
(a)Function:฀to฀provide฀a฀bypass฀air฀duct฀for฀idle-speed,฀control฀the฀bypass
air฀capacity฀by฀changing฀the฀cross-section฀area฀of฀channel,฀and฀effect฀a฀closed-
loop฀control฀over฀the฀rotating-speed฀while฀engine฀is฀running฀at฀idle-speed.
(b)Principal:One฀piece฀of฀permanent฀magnet,฀which฀may฀rotate฀freely฀on
shaft฀inside฀the฀idle-speed฀adjustor,฀is฀rigidly฀connected฀with฀one฀piece฀of
rotating฀slide฀block;฀And฀the฀permanent฀magnet฀is฀able฀to฀rotate฀when
driven฀ by฀ the฀ magnetic฀ field฀ of฀ coil,฀ and฀ the฀ slide฀ block฀ will฀ rotate
simultaneously;฀The฀size฀of฀bypass฀air฀capacity฀could฀be฀adjusted฀as฀the
opening฀degree฀of฀bypass฀air฀duct฀depends฀on฀the฀angle฀position฀of฀slide
block,฀which฀is฀controllable฀by฀the฀electrical-pulse฀occupation฀rate฀output
from฀the฀electronic฀controller.
(c)Installation฀position:฀on฀the฀throttle฀valve฀unit.
(d)Symptom:฀too฀much฀high฀idle-speed,฀idle-speed฀flameout,฀etc.
(e)Simple฀measurement฀method:
(after฀ disconnection฀ of฀ joint Have฀ digital฀ multimeter฀ adjusted฀ to
the’ohm’position,฀connect฀two฀pens฀with฀Pin฀1฀&2฀of฀adjustor฀respectively;
The฀rated฀resistance฀when฀at฀20 ฀shall฀be฀17.5 after฀connection฀of
joint Start฀the฀engine฀and฀have฀it฀running฀at฀idle-speed;฀Put฀your฀hand
gently฀on฀EWD3,฀you฀will฀feel฀a฀slight฀trembling.
10.฀Idle-speed฀actuator-step฀motor M7.9.7
(a)Function:฀to฀provide฀a฀bypass฀air฀duct฀for฀idle-speed,฀control฀the฀฀bypass
air฀capacity฀by฀changing฀the฀cross-section฀area฀of฀channel,฀and฀฀effect฀a฀closed-
loop฀control฀over฀the฀rotating-speed฀while฀engine฀is฀running฀at฀idle-speed.
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