Many enthusiasts looking to enhance the performance of their classic 1986 Mustang 5.0 often consider modifications like removing the Exhaust Gas Recirculation (EGR) system. This is a modification aimed at creating a cleaner engine bay, and potentially cooler intake air by eliminating a source of heat and carbon deposits to the intake manifold. However, owners often wonder about the On-Board Diagnostics system their vehicle employs – is it OBD1 or OBD2? And how does this impact an EGR delete?
For the 1986 model year, the Mustang 5.0, like most vehicles of this era, utilizes an OBD1 system. OBD2, the more advanced and standardized system, became mandatory in the United States in 1996. Understanding this distinction is crucial when planning modifications like an EGR delete, especially concerning the engine’s computer (PCM or ECU) and potential check engine lights.
Removing the EGR valve without addressing the sensor inputs can lead to issues with how the engine runs. The original post from a forum highlights this problem effectively: “Without this the computer will assume the EGR is stuck open when removed, causing a rough running engine.” This is because the engine computer expects to see feedback from the EGR Valve Position (EVP) sensor. When the EGR system is removed, the sensor signal is lost, and the computer interprets this as a malfunction.
To circumvent this issue, especially in OBD1 systems like the 1986 Mustang 5.0, a common solution is to use an EGR eliminator. These devices, as mentioned in the forum post, are designed to send a simulated signal to the computer, mimicking a closed EGR valve. “EGR Valve Position Sensor Eliminators send a 0.50volt CLOSED EGR signal to the computer. The computer then knows the EGR is permanently closed. Keeps the annoying CHECK ENGINE light OFF, and more importantly keeps the engine running smoothly.”
The installation process for an EGR eliminator on a 1986-1993 5.0L Mustang, and potentially other similar Ford models from 1986-1995 with a light gray EVP sensor, is typically straightforward:
- Disconnect the EGR Valve Position sensor (EVP). Carefully inspect the connector for any corrosion and ensure dielectric grease is present on the terminals for good electrical contact.
- Plug in the EGR Eliminator into the EVP harness connector.
- Secure the eliminator by zip-tying it to the engine bay to prevent vibration damage.
It’s important to note that an EGR eliminator only addresses the electrical aspect of the EGR system. For a complete EGR delete, it is still necessary to physically remove the EGR valve and related vacuum lines. The original forum advice is sound: “Please take the time to remove and cap off vacuum lines. If you are leaving the EGR valve on the intake confirm that it is fully closed. A leaky EGR will cause more engine problems. It’s best to remove the EGR spacer, or put a block off plate over the opening.” This ensures no vacuum leaks and a truly cleaner intake system.
In conclusion, for owners of a 1986 Mustang 5.0 with its OBD1 system considering an EGR delete, using an EGR eliminator in conjunction with physically removing the EGR components is a viable approach. This method can help avoid check engine lights and maintain smooth engine operation while achieving the desired benefits of EGR removal. While newer OBD2 systems often require more complex tuning solutions, the EGR eliminator provides a practical solution for these classic OBD1 Ford vehicles.
