Doosan G643, Руководство по обслуживанию

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G643(E) Service Manual Chapter 6. LPG FUEL DELIVERY SYSTEM 216
AVV (Air Valve Vacuum) Testing
Purpose of Test
Check for excessive or inadequate pressure drop
across CA100 mixer.
AVV Test Hardware
1. Union Tee fitting, 1/4” (6.35mm) NPT
with three 1/4” (6.35mm) NPT x 1/4” (6.35mm)
hose barbs
2. Vacuum hose
3. 0-20” H2O differential pressure Magnehelic gauge
AVV Test
1. Install Union Tee fitting in the hose between the
FTVs and the AVV fitting. Connect this fitting to
the low pressure port of the Magnehelic gauge
(Figure 37).
2. Leave high pressure port of the Magnehelic
gauge exposed to ambient pressure (Figure 37).
3. With the engine fully warmed up and running at
idle (750 rpm) place the transmission in Neutral.
The AVV should be between 5” and 8” H2O of
pressure vacuum.
4. If the measured pressure drop is excessively high,
check for sticking or binding of the diaphragm air
valve assembly inside the mixer. Replace mixer if
necessary.
5. If the measured pressure drop is low, check for
vacuum leaks in the manifold, throttle, mixer,
TMAP sensor and attached hoses.
Figure 37. Magnehelic Gauge Connection
Ignition Timing Adjustment
With the MI-07 system, ignition-timing advance is
controlled by the SECM.
The initial ignition timing setting of the distribytor is
described in chapter 4 Ignition System.
Idle Mixture Adjustment
NOTE : Be sure engine is fully warm (ECT>167°F
[75°C]) before performing the idle mixture
adjustment.
G643 LP Fuel Systems with O2 Sensor
Idle Adjustment
1. Install mixer and a UEGO or HEGO sensor. (A
UEGO sensor should be used when desired phi
settings are not at stoichiometric.)
2. After the mixer is installed, start and warm up the
engine to normal operating temperature
(ECT>167°F [75°C]). Also ensure that the vehicle
drive train and hydraulic systems are at normal
operating temperatures per vehicle manufacturer
recommendations.
3. Allow the engine to reach steady state at idle.
4. While monitoring the output of the UEGO or
HEGO sensor adjust the idle screw using a
standard screwdriver until the desired phi reading
is achieved (phi = 1.00 to 1.01 is optimal). To
make the mixture richer, turn the screw clockwise;
to make the mixture leaner, turn the screw
counter-clockwise.
5. Rev the engine to take it off of idle and let it return
to idle.
6. Once the engine has reached steady state at idle,
verify the phi reading. Adjust further as needed.