G424F(FE) Service Manual
Chapter 6. LPG FUEL DELIVERY SYSTEM
187
Factory Adjustment Procedure:
NOTE :
Be sure engine is fully warm (ECT>167°F
[75°C]) before performing the idle mixture
adjustment.
1.
Operating the engine on LPG fuel, start the
engine and permit it to warm up until the coolant
temperature (ECT on Mototune display) is
approximately 167°F (75 oC).
2.
Adjust the load until MAFPort equals 3.3 to 3.5
g/sec.
3.
Mototune display parameter LP Fuel Control must
display “Closed Loop”.
4.
Use the Mototune Service Tool to monitor Duty
Cycle % on the Mototune display.
5.
To adjust the idle mixture screw, use a hex or
Allen-type wrench. Turning the screw in
(clockwise) should increase the duty cycle; turning
the screw out (counterclockwise) should decrease
the duty cycle.
6.
Adjust the idle mixture screw on the mixer until a
reading of 35-55% is reached for the FTV Duty
Cycle in Closed Loop Idle (Figure 41). If engine
idle performance is unstable, screw the idle screw
in slightly to see if stability is obtained, but in no
case should duty cycle exceed 60%.
Figure 41. FTV Duty Cycle Percentage Displayed on
Service Tool
7.
Use the accelerator pedal to increase rpm above
idle momentarily (rev the engine) then release the
pedal to return to idle rpm. The duty cycle setting
should remain within the adjustment range (35-
55%). Place your thumb over the adjustment port
for a more accurate reading by preventing air from
leaking past the mixture adjustment screw, which
may cause the duty cycle to decrease.
8.
If the FTV duty cycle reading is above 55% adjust
the idle adjustment screw outward and re-check
the duty cycle reading. Continue to do this until
the FTV duty cycle reading is within the optimum
range (35-55%) and engine rpm is stable. DO
NOT adjust the screw so far outward that the
tamper proof cap cannot be installed. A duty cycle
measurement at Closed Loop Idle of 25-60% is
acceptable if the optimum range of 35-55%
cannot be reached through adjustment. If the FTV
duty cycle cannot be adjusted below 60%, the
mixer is faulty and should be replaced.
NOTE :
If the FTV Duty Cycle reading is NOT
between 25-60%, check for possible vacuum leaks,
manifold leaks, or a faulty mixer.
9.
Turn the ignition key to the OFF position to shut
down the engine.
10.
Install the tamper proof cap on the idle mixture
screw adjustment port using a large pin punch,
so that no further adjustments can be made
(Figure 42).
Figure 42. Installing Tamper Proof Cap
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Страница 153: ...G424F FE Service Manual Chapter 5 Engine Management System EMS 151 Figure 22 SECM Wiring Diagram for G424FE LP System ...
Страница 162: ...G424F FE Service Manual Chapter 5 Engine Management System EMS 160 SECM Wiring Diagrams for G424F LP Engine ...
Страница 230: ...G424F FE Service Manual 228 Chapter 8 Basic Troubleshooting Irregular Idling Or Engine Is Suddenly Stopped ...
Страница 231: ...G424F FE Service Manual 229 Chapter 8 Basic Troubleshooting Engine Hesitation Or Insuffient Accelelation ...
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