Pre-purchase inspection of used cars

Engine mechanical failure can lead to the immediate scrapping of a used car. The most scientific, non-disassembly and non-destructive method, the In Cylinder Pressure Transducer (CPT), allows for the following analysis. Currently, analysis is available for gasoline, LPG, and hybrid vehicles, with diesel engine support planned for the future.

1. Engine compression pressure measurement (a key indicator of engine health)
2. Intake valve condition diagnosis (non-opening, advance, retarded, etc.)
3. Exhaust valve condition diagnosis (non-opening, valve clearance, advance, retarded, etc.)
4. Catalyst plugging & exhaust blockage (numerical pressure measurement)
5. Crank & camshaft timing alignment
6. Camshaft (intake, exhaust) & lift wear failure
7. Excessive compression failure due to damaged piston rings
8. Head gasket leakage, etc. Other engine mechanical condition analysis

Engine mechanical failure? What could it be? It's simple. Most often, it involves engine replacement, and if you're lucky, just the head. Either way, the maintenance costs are substantial. Therefore, these engine mechanical failures can be scientifically analyzed in advance using waveform analysis using a cylinder pressure sensor. This analysis analyzes the electrical signals of the volume (pressure and vacuum) that change during cylinder, piston, intake, and exhaust valve operation without disassembling the engine, enabling on-site diagnosis.

The fuel pump, along with the starter motor and alternator, is a safety-critical component that can prevent engine stalls or stalling during driving. When purchasing or selling a used car, the fuel pump's condition can be scientifically analyzed through waveform analysis. This allows for predictive maintenance and troubleshooting before the engine stalls or stalls. The photo shows a waveform analysis of a Mercedes-Benz S550 fuel pump motor, showing excellent condition.

1. The fuel pump is aging and struggling to operate properly.
2. The fuel filter or hose is clogged.
3. The fuel pump motor fuse and relay status.
4. The wiring and connector status from the hub box to the motor.
5. The motor's rotations per minute can be measured.
6. The current consumed by the fuel pump can be measured.
7. Other fuel pump and fuel supply status analysis.

Fuel pump motors typically have eight segments, and it's possible to identify which of these eight segments is malfunctioning. By analyzing the electrical signal waveforms, scientific analysis can be used to prevent engine failures and stalls. Furthermore, significant situational analysis, such as pump aging, is also possible.

Alternators are also called generators. Mechanical failures are easily detected by noise, but electrical failures are often undetectable. This can lead to engine stalling while driving and pose a safety hazard. By analyzing electrical signal waveforms with a scope, alternator failures can be predicted in advance. This is a must-check item when buying or selling a used car.

1. Diode semiconductor failure status (usually six)
2. Brush contact status (electrical failure)
3. AC current amplification (ripple voltage) measurement

One of the most common faults in alternators is the brushes, and diodes that convert AC to DC are also prone to failure. Analyzing alternator electrical signals with an oscilloscope can scientifically identify potential failures and enable predictive maintenance.

The starter motor can be located in a very difficult location on some vehicles, making diagnosing starter motor failures challenging. However, Becomcar can predict starter motor failures in advance by analyzing electrical signals using an oscilloscope. This allows for non-disassembly diagnosis and preventative maintenance.

In the case of starter motors, failures most often occur in the solenoid switching element, brushes, and stator. By analyzing electrical signal waveforms with an oscilloscope, it's possible to predict the likelihood of near-term failure. This means that it's possible to do so not through intuition but through scientific electrical signal analysis. This process involves disassembling and repairing a faulty starter motor. This means that failures in these areas can be predicted in advance.

Most modern vehicle control systems rely on CAN bus data communication. CAN communication protocols vary by vehicle, but common CAN protocols include CAN HIGH & LOW, MOST, Flexray, LIN, K-Line, and Ethernet. Some vehicles use up to 15 different communication protocols. The waveforms show normal CAN HIGH & LOW signals, but then malfunction.

1. Vehicle drivetrain, including the engine and transmission
2. Device components, such as side mirrors, sunroofs, and tailgates
3. Most other functions are controlled via CAN communication.

The waveform is different for each communication protocol. LIN BUS is a 0V ~ 12V square waveform, and CAN HIGH & LOW is a square waveform with 3.5V (HIGH) above and 1.5V (LOW) below based on 2.5V. Since each communication protocol has its own waveform characteristics, it is necessary to first understand the communication protocol. The data photo is the process of diagnosing the LIN BUS communication status.

A closer look at the ignition coil waveform on a 2022 Honda Accord Hybrid with approximately 55,000 km of travel. One ignition cycle represents the firing of all four cylinders. The engine rotates 720 degrees. Examining each cylinder individually, we examine the TDC and ignition timing for each cylinder.

This is a record of the ignition coil waveform during a comprehensive health checkup after purchasing a used car. The waveform is very stable, with no unusual features. The Accord is still using the original Honda ignition coil and spark plugs from its factory installation. The ignition coil current for all four cylinders is very stable, drawing approximately 11.6A.

Catalyst deterioration fault codes P0420 and P0430 can occur in all internal combustion engine vehicles from all automakers. While this varies depending on the fuel-fuel ratio calculation technology, in the case of zirconia oxygen sensors, pre-catalyst and post-catalyst oxygen sensor waveforms are measured and used for catalyst diagnosis.

Catalyst deterioration fault codes P0420 and P0430 can occur in all internal combustion engine vehicles from all automakers. While this varies depending on the fuel-fuel ratio calculation technology, in the case of zirconia oxygen sensors, pre-catalyst and post-catalyst oxygen sensor waveforms are measured and used for catalyst diagnosis.

We scan the entire vehicle for fault codes, perform a detailed diagnosis, and provide repair recommendations. When selling or purchasing a used car, it's important to scan the entire electrical system for fault codes to identify invisible issues. While visible leaks, such as fuel leaks, are easy to fix and inexpensive, invisible electrical system failures can often be quite stressful.

Through data analysis of fault codes such as lean or rich fuel ratios and fuel correction values, we suggest additional inspection components and maintenance directions. The fuel correction value for all internal combustion engines is a crucial indicator for analyzing numerous vehicle conditions, including mechanical failures, timing, fuel, and ignition. This is why fuel correction value diagnosis is essential. It provides the fastest way to determine overall engine condition.

Of course, we also provide visual inspection services for the engine room and undercarriage. We perform general inspections, including those for signs of accidents, as well as those specifically requested by the customer. This requires access to a repair shop or a performance lift.

In addition to measuring cylinder pressure sensor waveforms, we also provide additional visual inspections, such as piston, valve, and cylinder wall condition, using an endoscope, if necessary, for each vehicle. This service may not be available for each vehicle model or engine type and configuration. The decision to include an endoscope inspection will be made through prior consultation.

A visual inspection of the ignition coil and spark plugs may also be necessary. A visual inspection may also be performed if a diagnostic scan reveals a misfire or a fault code. Inspection services vary depending on the vehicle, engine, and intake structure.

When purchasing a used hybrid vehicle, it's crucial to check the HV battery's remaining lifespan, maximum and minimum HV battery cell voltages, and HV battery insulation resistance to ensure they're in good working order. The used car inspection that led to my purchase was the 9th-generation Honda Accord Hybrid.

This is the most basic diagnostic item, even when purchasing or selling a used car. In fact, these items are sufficient for a performance inspection. However, for reconfirmation, check for paint marks on key areas of the vehicle.