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.

Integrated circuits list +This table lists the IC's on the PCB.Part numberFunction#UsageDatasheetMC68332Main MCU1All functions28F0101Mb flash memory2Storage of the binary (program)TC55257256Kb SRAM1Runtime memoryL4937Dual multifunction voltage regulator1Power supplyAN82526Can interface1ComunicationTLC546ADC (8-Bit, 20 channel, 40k SPS)1Sensor readingLM1815Sensor amplifier1Crankshaft sensor amplifierL9842Octal Power Driver74HC00Quad positive NAND gate274HC02Quad NOR gate174HC03Quad NAND gate (open drain)274HC146 Hex inverting schmitt triggers374HC74Dual D type flip-flop174HC123Dual monostable multivibrator1CA3262EQuad 700 mA driver1DI triggeringTLC274Quad op-ampMTP3055VN-channel MOSFET TO-2203BCV drivers (high current)MTD3055VLN-channel MOSFET DPAK SMD104 Injector drivers 2 EVAP purgue valve drivers 1 O2 sensor preheating 1 Vacuum pump driver 1 IAC valve driver

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 the camshaft position detector and knock sensor redundant. This function also enables the 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 is however most accurate for the SAAB 900.

Fuel

Fuel injector valves

The fuel injector valves are of a solenoid type with a needle and seat. They are opened by a current flowing through the injector's coil and are closed by a strong spring when the current is switched off. To ensure as optimal combustion as possible and with that lower exhaust emission the injectors are equipped with four holes, which gives a good distribution of the fuel. The squirts of fuel are very exact positioned (two jets on the backside on each inlet valve). This put very high demands on the fixation of the injectors. To secure this fixation the injectors are fixed in pairs by a special retainer between cylinders 1 – 2 and 3 – 4. The injectors are electrically supplied from the main relay, while the ECU grounds the injectors.

Fuel injection

Pre-injection

When the ignition is switched on, the main relay and fuel pump relay are activated during a few seconds. As soon as the ECU gets the cranking signal (from the crankshaft sensor) it initiates a coolant temperature dependent fuel injection with all four injectors simultaneously which ensures a fast engine start. If the engine is started and shortly after is switched off a new pre-injection is initiated after the ignition has been switched off for 45 seconds.

Calculating of injection time

To decide how much fuel needs to be injected into each intake runner the ECU calculates the air mass that had been drawn into the cylinder. The calculation makes use of the cylinder volume (the B204 engine has a displacement of 0.5 litres per cylinder). That cylinder volume holds equal amount of air which has a density and thus a certain mass. The air density is calculated using the absolute pressure and temperature in the intake manifold. The air mass for combustion has now been calculated and that value is divided by 14.7 (stoichiometric relation for gasoline mass to air mass) to determine the required fuel mass for each combustion to inject. Since the flow capacity of the injector and the density of the fuel (pre programmed values) are known, the ECU can calculate the duration of the injection.

Using the oxygen sensor 1 the injection duration is corrected so stoichiometric combustion is obtained. When hard acceleration occurs, the lambda correction is masked and Wide Open Throttle (WOT) enrichment occurs for maximum performance. When opening the throttle, acceleration enrichment (accelerationsupprikning in Swedish) occurs and when closing the throttle deceleration emaciation (decelartionsavmagring in Swedish) occurs. During a cold start and warm up, before lambda correction is activated, coolant temperature dependable fuel enrichment occurs. With a warm engine and normal battery voltage the duration of injection varies between 2,5 ms at idle and approx. 18 – 20 ms at full torque.

Lambda correction

The catalyst requires that the fuel/air mixture is stoichiometric. This means that the mixture is neither rich nor lean, it is exactly 14,7 kg air to 1 kg gasoline (Lambda=1). That is why the system is equipped with an oxygen sensor in the forward part of the exhaust system. The sensor is connected to pin 23 in the ECU and is grounded in the ECU via pin 47. The exhaust fumes pass the oxygen sensor. The content of oxygen in the exhaust fumes is measured through a chemical reaction, this results in an output voltage. If the engine runs rich (Lambda lower than 1) the output voltage would be more than 0.45 V and if the engine runs lean (Lambda higher than 1) the output voltage would be less than 0.45 V. The output voltage swings about 0.45 V when Lambda passes 1. The ECU continuously corrects the injection duration so that Lambda=1 is always met. To be able to function the oxygen sensor needs to be hot, this requirement is met by electrically pre heat the sensor. The pre heating element is fed by B+ via fuse 38 and the main relay, the sensor is grounded in the ECU via pin 50. The ECU estimates the temperature on the exhaust gases (EGT) on the basis of the engine load and the engines RPM. At high EGT the electrical pre heating is disconnected. The lambda correction is masked during the engines first 640 revolutions after start if the coolant temperature exceeds 18°C (64°F) at load ranges over idle and under WOT or 32°C (90°F) at idle.

Adaptation

The ECU calculates the injection duration on basis of MAP and intake temperature. Injection duration are then corrected by multiplication of a correction factor, which is fetched from main fuel matrix (huvudbränslematrisen in Swedish) and is dependable on MAP and RPM. The need to correct the injection duration is due that the volumetric efficiency of the cylinder is dependent on the engines RPM. The last correction is made with the lambda correction, this results in a stoichiometric combustion (Lambda=1). The lambda correction is allowed to adjust the calculated injection duration by ±25%. The ECU can change the correction factors in the main fuel matrix on basis of the lambda correction, this ensures good driveability, fuel consumption and emissions when lambda correction isn’t activated. This is called Adaptation.

Pointed adaptation

If the ECU calculates the injection duration to 8 ms but the lambda correction adjusts it to 9 ms due low fuel pressure the ECU will "learn" the new injection duration. This is done by changing the correction factor for that particular RPM and load point in the main fuel matrix to a new correction factor resulting in 9 ms injection duration. The correction factor in this example will be raised by 9/8 (+12%). The pointed adaptation can change the points in the main fuel matrix by ±25%. Adaptation occurs every fifth minute and takes 30 seconds to finish, the criteria for the adaptation are: Lambda correction is activated and the coolant temperature is above 64°C (147F). During the adaptation the ventilation valve on the carbon canister is held close.

Global adaptation

The global adaptation on OBDII variants occurs during driving; on non OBDII variants the global adaptation occurs 15 minutes after engine shut down. When the engine is inside a defined load and RPM range (60 – 120 kPa and 2000 – 3000 RPM) no pointed adaptation will occur all points in the fuel matrix will be changed instead by a multiplication factor. Global adaptation can change the points in the main fuel matrix by ±25% (Tech2 shows ±100%). Adaptation occurs every fifth minute and takes 30 seconds to finish, the criteria for the adaptation are: Lambda correction is activated and the coolant temperature is above 64°C (147F). During the adaptation the ventilation valve on the carbon canister is held close.

Fuel cut

With fully closed throttle and engine RPM over 1900 RPM and with third, fourth and fifth gear a fuel cut will occur after a small delay (some second). On automobiles with automatic transmission fuel cut is active in all stages. The injectors are reactivated when the RPM hits 1400 RPM.

Fuel consumption measurement

The wire from the ECU to the third injector is also connected to the main instrument. The main instrument calculates the fuel consumption based on the injection pulses duration. The fuel consumption is used to help getting an accurate presentation of the fuel level in the fuel tank and to calculate average fuel consumption in SID.

Turbo boost pressure

Basic charging pressure