Trionic T5.5 is an engine management system in the Saab Trionic range. It controls ignition, fuel injection and turbo boost pressure. The system was introduced in the 1993 Saab 9000 2.3 Turbo with B234L and B234R engine. Changes Since 1994 a number of changes have occurred. 1995. Four wire oxygen sensor, electronic heat plates in intake manifold (not in US and CA markets). K line is connected via VSS (Vehicle Security System) to enable immobilizing (certain markets). Vacuum pump for the vacuum servo assisted brake system with some control from Trionic is used on automobiles with automatic transmission. 1996. OBD II diagnostics on US and CA markets, which means two lambda probes. 1996, 5. Leakage diagnostics of the EVAP system on the OBD II variant. 1997. Heat plates are removed. 1998, 5. (Saab 9-3). K-line is connected via MIU (Main Instrument Unit) to enable immobilizing from TWICE (Theft Warning Integrated Central Electronics) (not in software for markets: US and CA). Fuel pump relay is electrically supplied from main relay. Request signal for Air Condition is feed from MIU. Electrical pre heating on oxygen sensor is supplied from main relay. Requested boost pressure is raised somewhat on automobiles with manual gearbox. SID message when leakage in EVAP-system is confirmed, applicable in On-Board Diagnostics II variants. 1998. Two new engine variants; B204R and B204E, B204E were available with manual gearbox only and demanded high octane gasoline to deliver the stated torque. B204E is lacking boost pressure control, this engine wasn’t available on US and CA markets. On the Swedish market automobiles is equipped with the B204E engine, OBD II diagnostics and ORVR (On board Refuelling Vapour Recovery system), a system that makes sure that the gasoline vapour doesn’t escape into the surrounding air during refuelling. Description Saab Trionic’s ignition system consists of an ignition cassette with four ignition coils, one for each spark plug. The ignition system is capacitive. The spark plugs are used as sensors to detect combustion and pre-ignition/pinging. This renders camshaft position detector and knock sensor redundant. This function also enables effective detection of misfires, which is an OBD II demand. The fuel injection is fully sequential and is dependent on the MAP (Manifold Absolute Pressure). Boost pressure control (L and R engines) utilises a solenoid valve pneumatically connected to the turbocharger’s waste gate. The system was fitted on models Saab 900, Saab 9000 and Saab 9-3. This information