Engine Diagnostics
Reviewing the provided description and system operation information will help determine if the condition described by the customer is causing defective or normal engine operation.
Strategy based diagnostics
- Review the system operations to familiarize yourself with the system functions, see Section 1A1, General Engine Data - 2.0 Diesel and Section 1F1, Engine Controls - 2.0 Diesel - General.
- Perform a diagnostic check on the engine management system, refer to Section 1F1, Engine Controls - 2.0 Diesel - Diagnosis.
All diagnostics on the vehicle must follow a logical process. Strategy Based Diagnostics is a unified approach for repairing all vehicle systems. The process flow chart in strategy-based diagnostics can always be used to solve systemic problems. The diagnostic flow chart is the starting point from which to start when repairs are required. For a detailed explanation of strategy and flowchart based diagnostics, see Section 1F1, Engine Controls - 2.0 Diesel - Diagnosis.
Visual / physical examination
- Inspect the vehicle for post-sales equipment that may adversely affect engine performance.
- Inspect easily accessible or highly visible system components for clear signs of damage or conditions that may cause the symptom.
- Check the engine lubrication system as follows:
- is the oil level correct,
- is the viscosity of the lubricant correct,
- Is the oil filter properly applied and
- whether the oil is contaminated and whether there are carbon particles in it.
- Confirm the accuracy of the operating conditions under which engine malfunction occurs. Pay attention to factors such as:
- engine speed (rpm),
- ambient temperature,
- engine temperature,
- engine warm-up time and
- vehicle speed on the road.
- Compare the operating noises of the engine, if applicable, with those of a known good engine to ensure that a diagnosis of normal operating conditions is not being attempted.
Intermittent
For intermittent faults, test the vehicle under the same conditions reported by the customer to verify that the system is operating correctly.
Compression test
Attention! Disconnect the crankshaft position sensor connector to prevent the engine from starting (CKP). But do not remove the fuel pump fuse from the fuse box or disconnect the high pressure pump connector to prevent the engine from starting. Since the high pressure pump is lubricated with fuel by the fuel pump, if the fuel pump fuse is removed or the high pressure pump connector is disconnected, the high pressure pump will be damaged. Check the compression pressure for each cylinder. Low compression pressure can cause valve and cylinder failure. When checking the compression of the cylinders, take into account the following conditions:
- The engine must be at normal operating temperature.
- The battery must be fully or almost fully charged.
- The duration of cranking the engine to check compression should be less than 10 seconds at intervals of 30 seconds.
- Disconnect the crank angle sensor connector (CKP).
- Remove the fuel pump relay from the fuse box in the engine compartment.
- Remove injector #1 from cylinder head.
- Crank the engine with the starter for 5 seconds to remove any foreign matter in the cylinder.
- Install compression pressure gauge (EN-48248) into the injector hole of the cylinder being tested.
Note: Compression pressure gauge and injector have a similar configuration. Therefore, the procedure for installing a compression pressure gauge is similar to installing an injector. See Section 2F1, Engine Controls. Section 1F2, Engine Controls.
- Using the vehicle's starter, rotate or crank the engine for no more than 10 seconds at 30 second intervals.
Attention! During the compression pressure test in the cylinder being tested, fuel may leak from the fuel lines on the side of the injectors. To prevent fuel from dripping onto the engine cover from the fuel lines, substitute a container.
- Normally, the compression pressure gauge reading for each of the cylinders should be 2600 kPa (377 psi inch). The maximum pressure difference between each cylinder is approximately 10%.
- View the meter data obtained from the four "aftershocks" on each cylinder from cranking the engine crankshaft. Explanations of the indications are given in the following descriptions:
- Normal condition: Rapid and uniform increase in compression pressure to a certain value in each cylinder.
- Faulty piston rings: Compression pressure is low on the first stroke and tends to increase on subsequent strokes, but still does not reach normal compression pressure. Compression pressure improves significantly when oil is added to the cylinder.
- Faulty valves: Low compression pressure on the first stroke. The compression pressure does not tend to increase on subsequent cycles. Compression pressure does not improve significantly when oil is added to the cylinder.
- Repeat steps 1 through 7 of the above procedure on the remaining cylinders.