Hyundai Sonata LF: General Information / Repair procedures

Hyundai Sonata LF 2014-2019 Service Manual / Engine Mechanical System / General Information / Repair procedures

Compession Pressure Inspection
   
If the there is lack of power, excessive oil consumption or poor fuel economy, measure the compression pressure.
1.
Make sure the oil in the crankcase is of the correct viscosity and at the correct level and that the battery is correctly charged. Operate the vehicle until the engine is at normal operating temperature. Turn the ignition switch to the OFF position.
2.
Remove the engine cover.
3.
Disconnect the injector extension connector (A) and the ignition coil connectors (B).

4.
Remove the ignition coils (A).

5.
Remove the spark plugs.
Using a 16mm plug wrench, remove the 4 spark plugs.
6.
Check the cylinder compression pressure.
(1)
Insert a compression gauge into the spark plug hole.

(2)
Set the throttle plate in the wide-open position.
(3)
While cranking the engine, measure the compression pressure.
   
Always use a fully charged battery to obtain engine speed of 250rpm or more.
(4)
Repeat step 1) through 3) for each cylinder.
   
This measurement must be done in as short time as possible.
Compression pressure
Standard : 1225.83kPa (12.5kg/cm?, 177.79psi) (200~250 rpm)
Minimum : 1078.73kPa (11.0kg/cm?, 156.46psi)
Difference between each cylinder :
98kPa (1.0kg/cm?, 14psi) or less
(5)
If the cylinder compression in one or more cylinders is low, pour a small amount of engine oil into the cylinder through the spark plug hole and repeat step 1) through 3) for cylinders with low compression.
A.
If adding oil helps the compression, it is likely that the piston rings and/or cylinder bore are worn or damaged.
B.
If pressure stays low, a valve may be sticking or seating is improper, or there may be leakage past the gasket.
7.
Install the spark plugs.
Tightening torque :
7.8 ~ 9.8N.m (0.8 ~ 1.0kgf.m, 5.8 ~ 7.2lb-ft)
8.
Install the ignition coil.
Tightening torque :
9.8 ~ 11.8 N.m (1.0 ~ 1.2 kgf.m, 7.2 ~ 8.7 lb-ft)
9.
Connect the injector extension connector and the ignition coil connectors.
10.
Install the engine cover.

    Specifications

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