Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Engine Compression Inspection: Inspection
NOTICE:
- After this inspection, you must reset the PCM - Refer to: PCM Update () or PCM Reset () . Otherwise, the PCM will continue to stop the injectors from operating.
- Engine Compression - Inspect
Preconditions
- Engine Warmed Up
NOTE: Warm up the engine by raising the engine speed around 3,000 rpm until the cooling fan(s) comes on.
- HDS Connected
- Spark Plugs Removed
Procedure/Specifications
1. Select the following menu buttons on the HDS screen in sequence.
- PGM-FI (System Selection Menu)
- Function Test
- ALL INJECTORS STOP
2. Attach a compression gauge to the spark plug hole.
Tool Details
Name a Compression gauge 3. Step on the accelerator pedal to open the throttle fully, then crank the engine with the starter motor, and measure the compression.
Specifications (Compression Pressure)
Position Service Limit Each Cylinder Above 930 kPa (9.48 kgf/cm2 , 134.8 psi) 4. Measure the compression on the remaining cylinders.
Specifications (Maximum Variation)
Item Service Limit Difference between each cylinder Within 200 kPa (2.04 kgf/cm2 , 29.0 psi) Result
- If the measurement is not within specifications, perform a cylinder leak down test to determine the problem area. Then check the following items, and remeasure the compression:
- Camshaft timing
- Damaged or worn cam lobes
- Damaged or worn valves and seats
- Damaged cylinder head gasket
- Damaged or worn piston rings - Refer to: Block and Piston Inspection () or Piston, Ring, Pin, and Connecting Rod Inspection ()
- Damaged or worn piston and cylinder bore - Refer to: Block and Piston Inspection () or Cylinder Bore Honing ()
After Inspection
1. Select PCM reset - Refer to: PCM Update () or PCM Reset () to cancel ALL INJECTORS STOP with the HDS.
- Engine Warmed Up
Use the Manual With the Right Hardware
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
