Inlet Manifold Pressure

TM 9-2320-312-24-2

Testing and Adjusting Section

i01665958

Inlet Manifold Pressure - Test

SMCS Code: 1058-081

The efficiency of an engine can be checked by

making a comparison of the pressure in the inlet

manifold with the information given in the TMI

(Technical Marketing Information). The information

is also listed on the Fuel Setting And Related

Information Microfiche. This test is used when there

is a decrease of horsepower from the engine, yet

there is no real sign of a problem with the engine.

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The correct pressure for the inlet manifold is listed

Illustration 58

in the TMI (Technical Marketing Information). The

1U-5470 Engine Pressure Test Group

correct pressure is also on the Fuel Setting And

Related Information Microfiche. Development of

Refer to Special Instruction, SEHS8907, "Using

this information is performed under the following

the 1U-5470 Engine Pressure Test Group" for the

conditions:

instructions that are needed to use the 1U-5470

Engine Pressure Test Group. Refer to Operation

96 kPa (28.8 in Hg) dry barometric pressure

Manual, NEHS0818, "Using the 198-4240 Pressure

Indicator Tool Gp" for the instructions that are

25 C (77 F) outside air temperature

needed to use the 198-4240 Engine Indicator Test

Gp.

35 API rated fuel

Any change from these conditions can change the

pressure in the inlet manifold. The outside air may

have a higher temperature and a lower barometric

pressure than the values that are given above.

This will cause a lower inlet manifold pressure

measurement than the pressure in the TMI. Outside

air that has both a lower temperature and a higher

barometric pressure will cause a higher inlet

manifold pressure measurement.

A difference in fuel density will change horsepower

(stall speed) and boost. If the fuel is rated above

35 API, the pressure in the inlet manifold can be

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less than the pressure that appears in the TMI.

Illustration 59

If the fuel is rated below 35 API, the pressure in

Pressure Test Location

the inlet manifold can be more than the pressure

(1) Plug

that appears in the TMI. BE SURE THAT THE

AIR INLET OR THE EXHAUST DOES NOT HAVE

Use the following procedure in order to measure the

A RESTRICTION WHEN YOU ARE MAKING A

inlet manifold pressure:

CHECK OF THE PRESSURE.

1. Remove plug (1) from the air inlet cover.

Note: The electronic service tool may be used to

check the pressure in the inlet manifold.

2. Connect the 1U-5470 Engine Pressure Test

Group to the air inlet cover at the pressure test

Table 9

location.

Tools Needed

Note: A tee fitting or some other plumbing

Part Number

Part Description

Qty

component will be necessary to allow the boost

1U-5470

Engine Pressure Test Group

pressure sensor to be connected with a test

location.

198-4240

Pressure Indicator Tool Gp

3. Record the value.