Running Compression Test

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Run a compression and cylinder leakage test. Record the test results for each cylinder for reference. Refer to: Compression and Cylinder Leakage Test - Gasoline .
Using results of the compression test, cylinder leakage test, DTC's or other diagnostic methods, identify cylinders suspected of damage.

Create a chart to record the running compression test readings. Each cylinder should have 2 fields, one for idle and one for raised RPM.SAMPLE CHART

Idle	Raise RPM
Cylinder 1 idle Pressure	Cylinder 1 raised RPM pressure
Cylinder 2 idle Pressure	Cylinder 2 raised RPM pressure
Cylinder 3 idle Pressure	Cylinder 3 raised RPM pressure
Cylinder 4 idle Pressure	Cylinder 4 raised RPM pressure
Cylinder 5 idle Pressure	Cylinder 5 raised RPM pressure
Cylinder 6 idle Pressure	Cylinder 6 raised RPM pressure
Cylinder 7 idle Pressure	Cylinder 7 raised RPM pressure
Cylinder 8 idle Pressure	Cylinder 8 raised RPM pressure

Remove the spark plug from cylinder 1.
Install the pressure vacuum transducer.
Refer to the pressure vacuum transducer installed video below.

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1. Install the hose from a cylinder leakage tester kit in cylinder 1.
2. Attach the pressure vacuum transducer to the cylinder leakage tester hose. Connect the pressure vacuum transducer to the scan tool.
Courtesy of FORD MOTOR COMPANY
NOTE: Allowing the idle speed to stabilize will maximize pressure consistency in good cylinders and increase the ability to identify damaged cylinders.

Start the engine and allow the engine speed to stabilize.
Using the scan tool, disable the fuel injector for the cylinder being tested.
View the pressure graph displayed on the scan tool with the engine at idle. Record the maximum compression reading on the chart.
If the misfire occurs at an engine speed other then idle raise the engine RPM to that speed and record the maximum pressure on the chart. Quickly release the accelerator pedal once the desired engine speed has been reached.
Turn the ignition off.
Test the remaining cylinders in order.

Compare the results from the cylinders suspected of damage to the rest of the cylinders and to the Running Compression Chart. Use the Running Compression Chart to help determine the cause of the concern.Running Compression Chart

Results	Possible Source	Action
LOW pressure at idle and raised RPM on a single cylinder	Weak or damaged valve spring	CARRY OUT the Valve Train Analysis Component Test. Refer to: Valve Train Analysis - 2.0L EcoBoost (177kW/240PS) - MI4/2.5L Duratec - Hybrid (121kW/164PS) (BG) . INSTALL a new valve spring as necessary. REFER to the Engine article for this engine. TEST the system for normal operation.
	Incorrect valve clearance	ADJUST the valve clearance. INSTALL a new valve spring as necessary. REFER to the Engine article for this engine. TEST the system for normal operation.
	Bent or burned valve Worn valve guide Carbon build-up on valve stem (sticking valve)	INSTALL new cylinder head(s) as necessary. REFER to the Engine article for this engine. TEST the system for normal operation after the repair.
LOW pressure at raised RPM on a single cylinder	Weak or damaged intake valve spring	CARRY OUT the Valve Train Analysis Component Test. Refer to: Valve Train Analysis - 2.0L EcoBoost (177kW/240PS) - MI4/2.5L Duratec - Hybrid (121kW/164PS) (BG) . INSTALL a new valve spring as necessary. REFER to the Engine article for this engine. TEST the system for normal operation.
	Worn intake camshaft lobe Worn or damaged intake roller follower, rocker arm or push rod	CARRY OUT the Valve Train Analysis Component Test. Refer to: Valve Train Analysis - 2.0L EcoBoost (177kW/240PS) - MI4/2.5L Duratec - Hybrid (121kW/164PS) (BG) . INSPECT the valvetrain for damage or excessive wear. INSTALL new parts as necessary. REFER to the Engine article for this engine. TEST the system for normal operation.
	Incorrect intake valve clearance	ADJUST the valve clearance. REFER to the Engine article for this engine. TEST the system for normal operation.
	Damaged IMRC flaps.	REMOVE the intake manifold and INSPECT for loose or damaged IMRC flaps. INSTALL a new intake manifold as necessary. REFER to the Engine article for this engine. TEST the system for normal operation.
	Worn intake valve guide Carbon build-up on intake valve stem (sticking valve)	INSTALL new cylinder head(s) as necessary. REFER to the Engine article for this engine. TEST the system for normal operation after the repair.
HIGH pressure at raised RPM on a single cylinder	Weak or damaged exhaust valve spring	CARRY OUT the Valve Train Analysis Component Test. Refer to: Valve Train Analysis - 2.0L EcoBoost (177kW/240PS) - MI4/2.5L Duratec - Hybrid (121kW/164PS) (BG) . INSTALL a new valve spring as necessary. REFER to the Engine article for this engine. TEST the system for normal operation.
	Worn exhaust camshaft lobe Worn or damaged exhaust roller follower, rocker arm or push rod	CARRY OUT the Valve Train Analysis Component Test. Refer to: Valve Train Analysis - 2.0L EcoBoost (177kW/240PS) - MI4/2.5L Duratec - Hybrid (121kW/164PS) (BG) . INSPECT the valvetrain for damage or excessive wear. INSTALL new parts as necessary. REFER to the Engine article for this engine. TEST the system for normal operation.
	Incorrect exhaust valve clearance	ADJUST the valve clearance. REFER to the Engine article for this engine. TEST the system for normal operation.
	Worn exhaust valve guide Carbon build-up on exhaust valve stem (sticking valve)	INSTALL new cylinder head(s) as necessary. REFER to the Engine article for this engine. TEST the system for normal operation after the repair.
HIGH pressure at raised RPM across all, left or right bank of cylinders	Restricted exhaust	INSPECT the exhaust system for damage. TEST the exhaust for excessive backpressure. INSTALL new parts as necessary. REFER to the Exhaust System article for this engine. TEST the system for normal operation after the repair.

Clear all DTC's and KAM.