Though the Ford EEC-IV mass-air SEFI system is very adaptable, in stock form it cannot make the substantial changes necessary to provide the optimum air/fuel ratio for a 400hp engine such as ours.

The 1986-1993 Ford Mustang's EEC-IV has the capability to manually test for codes. Not just that, but you can also check the Continuous Memory codes that are stored in the system.

On the other hand, EEC IV is likely the most mule-headed and secretive management system ever in widespread use. Its complex inner workings are for all practical applications a secret of Ford's ...

The 1986-1993 Ford Mustang’s EEC-IV has the capability to manually test for codes. Not just that, but you can also check the Continuous Memory codes that are stored in the system.

The Sequential Electronic Fuel Injection (SEFI) system and its EEC-IV controller would become standard on the 1986 Ford Mustang GT and all 5.0-liter Mustangs through the 1995 model year. Though Bieber ...