Converting from OBD1 to OBD2: Is It Worth the Upgrade?

The world of automotive diagnostics has evolved significantly over the years. Early systems, known as OBD1, paved the way for the more standardized and comprehensive OBD2 (On-Board Diagnostics II). For owners of older vehicles still running on OBD1, the question often arises: is it possible, and worthwhile, to convert to OBD2? This article delves into the intricacies of Converting From Obd1 To Obd2, exploring the benefits, challenges, and alternative solutions for car enthusiasts and those seeking enhanced vehicle monitoring capabilities.

Understanding OBD1 and OBD2 Systems

Before tackling the conversion process, it’s crucial to understand the fundamental differences between OBD1 and OBD2.

OBD1, the predecessor, was not a standardized system. Each manufacturer often had its own diagnostic connector, communication protocol, and data parameters. This lack of uniformity meant that diagnostic tools were often manufacturer-specific and accessing vehicle data could be cumbersome.

OBD2, mandated in the United States for all cars manufactured after 1996, brought about standardization. It features a universal 16-pin Diagnostic Link Connector (DLC) and standardized diagnostic trouble codes (DTCs). OBD2 provides a more comprehensive set of diagnostic data, including emissions-related parameters, and uses standardized communication protocols, making it much easier to diagnose and monitor vehicle health with generic scan tools.

Is Converting from OBD1 to OBD2 Possible?

Technically, yes, converting a vehicle from OBD1 to OBD2 is possible, but it’s rarely a straightforward plug-and-play process. The feasibility and complexity of the conversion heavily depend on the vehicle in question, specifically the availability of an OBD2 version of the same engine or vehicle model.

In cases where a later OBD2 version of the engine exists – for example, switching a VW Corrado from OBD1 to OBD2 using parts from a later OBD2 VR6 engine – the conversion becomes more attainable. This often involves swapping a significant number of components including:

Engine Wiring Harness: The entire engine wiring harness from an OBD2-equipped vehicle is usually required.
ECU (Engine Control Unit): The OBD1 ECU needs to be replaced with an OBD2 compatible ECU.
Sensors: OBD2 systems often utilize different or additional sensors compared to OBD1, such as a rear O2 sensor or a different type of MAF (Mass Air Flow) sensor.
Intake Manifold and Throttle Body: In some cases, these components might need to be swapped to accommodate OBD2 sensors and functionalities.

However, for vehicles where an OBD2 variant was never produced, such as the early 90s Toyota MR2 mentioned in the original forum, the conversion becomes significantly more challenging. Finding a compatible powertrain and all necessary hardware to retrofit OBD2 can be a substantial undertaking.

The Challenges of OBD1 to OBD2 Conversion

Even in the “easier” scenarios where OBD2 parts are available from a similar engine, several hurdles need to be considered:

Wiring Complexity: Integrating an OBD2 wiring harness into an older OBD1 vehicle can be complex, requiring detailed wiring diagrams and potentially custom wiring work to connect to the vehicle’s fuse box and other systems.
Sensor Compatibility and Mounting: OBD2 sensors might have different mounting points or require modifications to the engine or chassis to be properly installed. Reluctor rings for crank/cam sensors, injector impedance, and even the number of teeth on sensor rings can differ, requiring careful attention.
ECU Programming and Compatibility: Ensuring the OBD2 ECU is compatible with the older engine and vehicle systems can be a challenge. While some ECUs might be adaptable, others might require custom tuning or programming to function correctly, especially if the engine specifications are not exactly identical.
Emissions System Integration: OBD2 places a greater emphasis on emissions monitoring, requiring components like catalytic converters and EVAP (Evaporative Emission Control) systems to be functional and properly connected. Retrofitting these systems to an older vehicle can add significant complexity and cost.
Time and Cost: The entire conversion process can be time-consuming and expensive, requiring sourcing parts, potentially custom fabrication, and significant labor.

Why Consider OBD2 Conversion?

Despite the challenges, there are reasons why some car enthusiasts might consider converting to OBD2:

Enhanced Diagnostic Capabilities: OBD2 offers standardized and more comprehensive diagnostic data, making it easier to read trouble codes, monitor engine parameters, and diagnose issues using readily available and affordable OBD2 scan tools.
Compatibility with Modern Tools and Track Assistants: Many modern automotive tools, scan gauges, and track day assistants rely on OBD2 connectivity for data logging and performance analysis. Converting to OBD2 can open up compatibility with these devices.
Data Logging for Performance Tuning: While basic OBD2 data logging can be slow, having an OBD2 port can still be beneficial for accessing some engine parameters for basic performance monitoring or tuning adjustments.

Alternatives to OBD2 Conversion: Simpler and Often More Effective Solutions

For many owners of OBD1 vehicles, especially those primarily interested in performance monitoring and data logging, converting to OBD2 might be overkill. Several more practical and often superior alternatives exist:

Standalone ECUs: For performance-focused applications, especially in modified vehicles, a standalone ECU offers a far more comprehensive and customizable solution. Standalone ECUs often provide advanced data logging capabilities with high data rates, compatibility with a wide range of sensors, and extensive tuning options. They bypass the limitations of both OBD1 and basic OBD2 data logging, offering features tailored for performance and racing.
OBD1 Data Logging Solutions: Many OBD1 vehicles, despite not being standardized, still have ECUs capable of outputting diagnostic data. Solutions like ALDLdroid for GM vehicles or specialized tools for other makes can tap into this OBD1 data stream. While it might require specific software and interfaces, it avoids the complexity of a full OBD2 conversion and can provide valuable data.
Dedicated Data Acquisition Systems: For track enthusiasts seeking detailed performance data, dedicated data acquisition systems (DAQ) offer the highest level of performance and flexibility. These systems use direct sensor inputs and often CAN bus communication (which, while sometimes present on OBD2 connectors, is not technically part of the basic OBD2 standard) to log data at high frequencies and with a wider range of parameters than typically available through OBD2.

Key Considerations Before Attempting Conversion

Before embarking on an OBD1 to OBD2 conversion, carefully consider the following:

Your Goals: Clearly define why you want to convert to OBD2. If it’s primarily for basic diagnostics, OBD2 might be beneficial. However, if your aim is performance data logging or advanced tuning, standalone ECUs or dedicated DAQ systems are likely better investments.
Vehicle Specifics: Research the feasibility of conversion for your specific vehicle make and model. Are there documented successful conversions? Are compatible OBD2 parts readily available?
Technical Expertise and Resources: Assess your mechanical and electrical skills. OBD2 conversion can be a complex project requiring significant automotive knowledge, wiring skills, and access to tools and diagnostic equipment.
Cost-Benefit Analysis: Carefully weigh the potential costs of parts, labor (if you’re not doing it yourself), and time against the benefits of OBD2 conversion. Compare this to the cost and benefits of alternative solutions like standalone ECUs or OBD1 data logging.

Conclusion: Is OBD2 Conversion Worth It?

Converting from OBD1 to OBD2 is technically achievable, particularly if an OBD2 version of your engine exists. However, it’s often a complex, time-consuming, and potentially expensive undertaking. For basic diagnostic needs, OBD2 offers advantages in terms of standardization and tool availability. But for enthusiasts seeking enhanced data logging, performance tuning, or track day analysis, standalone ECUs or dedicated data acquisition systems usually provide a more effective and feature-rich path forward. Before considering OBD2 conversion, thoroughly evaluate your needs, vehicle specifics, and available alternatives to make an informed decision that best suits your automotive goals.