Ford's Thick Film Ignition (TFI) system debuted on the '86 Mustang. The TFI system features a toothed wheel reluctor that passes through a Hall Effect sensor called a Profile Ignition Pickup (PIP). Since the 5.0L EFI Mustang engine uses sequential EFI (SEFI), the toothed wheel has a signature window that is smaller than the others to denote cylinder number one to sequentially fire the injectors in the matching firing order. Ford had an issue with early PIP sensor failure, but the TFI system is generally considered a solid system. The TFI module can be replaced on the car, but PIP sensor replacement requires complete distributor disassembly.