Throttle Body/Intake Manifold Assembly; Idle Speed Adjustment (Rpm); Initial Governor Adjustment - Kohler LH630-775 Service Manual

Section 5B
EFI Fuel System

Throttle Body/Intake Manifold Assembly

Figure 5B-28. Upper Intake Manifold.
General
The EFI engines have no carburetor, so the throttle
function (regulate incoming combustion airflow) is
incorporated in the intake manifold assembly. The
manifold consists of a one-piece aluminum casting
which also provides mounting for the fuel injectors,
throttle position sensor, fuel rail, air baffle, idle speed
screw, and air cleaner assembly.
Service
The throttle body/intake manifold is serviced as an
assembly, with the throttle shaft, throttle plate, and
idle speed adjusting screw installed. The throttle
shaft rotates on needle bearings (non-serviceable),
capped with rubber seals to prevent air leaks.

Idle Speed Adjustment (RPM)

General
The idle speed is the only adjustment that may be
performed on the EFI system. The standard idle speed
setting for EFI engines is 1500 RPM, but certain
applications might require a different setting. Check
the equipment manufacturer's recommendation.
For starting and warm up, the ECU will adjust the
fuel and ignition timing, based upon ambient
temperature, engine temperature, and loads present.
In cold conditions, the idle speed will probably be
higher than normal for a few moments. Under other
conditions, the idle speed may actually start lower
than normal, but gradually increase to the
established setting as operation continues. Do not
attempt to circumvent this warm up period, or
readjust the idle speed during this time. The engine
must be completely warmed up for accurate idle
speed adjustment.
5B.20
Adjustment Procedure
1. Make sure there are no fault codes present in the
ECU memory.
2. Start the engine and allow it to fully warm up
and establish closed looped operation
(approximately 5-10 min.).
3. Place the throttle control in the ''idle/slow''
position and check the idle speed with a
tachometer. Turn the idle speed screw in or out
as required to obtain 1500 RPM, or the idle speed
specified by the equipment manufacturer.
4. The low idle speed adjustment can affect the high
speed setting. Move the throttle control to the full
throttle position and check the high speed.
Adjust as necessary to 3750 RPM (no load), or the
speed specified by the equipment manufacturer.
Figure 5B-29. Idle Speed Screw Details.

Initial Governor Adjustment

The initial governor adjustment is especially critical
on EFI engines because of the accuracy and sensitivity
of the electronic control system. Incorrect adjustment
can result in overspeed, loss of power, lack of
response, or inadequate load compensation. If you
encounter any of these symptoms and suspect them
to be related to the governor setting, the following
should be used to check and/or adjust the governor
and throttle linkage.
Idle Speed Screw