When dealing with fuel injectors, especially in OBD2 systems, it’s easy to get caught up in connector types. However, focusing solely on whether an injector “fits” the OBD2 clip can lead to serious problems. The real issue lies in understanding injector resistance – specifically, whether they are high resistance (saturated) or low resistance (peak & hold). Mismatching these types can fry your injectors or even your engine control unit (ECU), regardless of the connector.
Peak & Hold vs. Saturated Injectors: Decoding the Difference
There are two primary types of fuel injectors differentiated by their electrical resistance and how they are controlled:
- Saturated (High Resistance) Injectors: These injectors have higher resistance and are designed to be continuously powered (saturated). They are simpler to control and are commonly used in many stock applications.
- Peak & Hold (Low Resistance) Injectors: These injectors have lower resistance and require a different control strategy. They receive a “peak” current to rapidly open, and then a “hold” current to keep them open. This allows for faster response times and is often used for higher performance or larger injectors.
The critical point is that these injector types are not interchangeable without considering the electrical system they are designed for.
The Risk of Mismatched Resistance: Potential for Damage
If you install low resistance, peak & hold injectors into a system designed for high resistance, saturated injectors, you risk serious electrical damage. The system will attempt to deliver too much current to the low resistance injectors. This excessive current can overheat and potentially “fry” the injector coils. Worse, it can damage the injector driver circuitry within your ECU, leading to costly repairs.
Resistor Boxes: A Potential Solution for Peak & Hold Conversion
In some cases, when upgrading to larger, low resistance peak & hold injectors on a system designed for saturated injectors, a resistor box is used. This device adds external resistance to the circuit, mimicking the electrical load of high resistance injectors and protecting the ECU. However, this is a modification and needs to be done correctly.
OBD Connectors vs. Injector Resistance: Two Separate Issues
It’s important to understand that OBD1 or OBD2 connectors are a separate issue from injector resistance. You can find both saturated and peak & hold injectors with either OBD1 or OBD2 style connectors. Simply because an injector has an OBD2 clip doesn’t automatically mean it’s compatible with your OBD2 system in terms of resistance.
For example, some OBD1 Prelude injectors are low resistance peak & hold, while OBD2 Prelude injectors are high resistance saturated – and they use different connectors. Even if you were to adapt the connector, the electrical mismatch would still be a problem.
