Manufacturer Software Updates

When manufacturers develop a new vehicle model there may be unforeseen problems which only show after the effects of wear and tear. These problems which develop may affect exhaust emissions or driveability can sometimes only be corrected be updating the control unit software, in similar fashion to updating the drivers on a pc.

The type of microcontroller chip inside the control module will determine the method required to update software. In some cases this may require replacement of the program microchip , but on later vehicles updated software may be 'flash' programmed via the diagnostic connector.

Certain faults which occur to a particular vehicle model may alert the manufacturer to release a TSB or Technical Service Bulletin.

Updated calibration software is downloaded from the vehicle manufacturers website and transferred to the vehicle computer using either a dedicated tool or a computer and SAE J2534 (refers to Society of Automotive Engineers protocol) compliant interface

How we can help:

Check Engine light on:
The check engine light illuminates because the vehicle onboard computer has recognised a fault with part of the vehicles engine management system or engine operating parameters.The fault may be historical or current.
The fault will be logged in onboard computer memory and stored as a fault code.
First process is to liase with the customer for a description of the fault, then retrieve the stored fault codes from the engine control unit using scan tool diagnostic equipment and record details of the stored codes.
Next, the scan tool is used to clear the recorded historical fault codes from onboard (obd) computer memory. This is done because people often have a go at repairing faults themselves without access to diagnostic test equipment and by unplugging sensors can log false codes onto the obd computer memory. A visual check on the engine is carried out with reference to stored fault codes before the engine control unit memory is rechecked to see if any fault codes immediately re occur. Appropriate action to investigate & rectify the cause of the fault code(s) can be taken subject to customer liason and approval.
Many systems can be tested further by use of dynamic data recording and individual actuator testing (used to check individual wiring & components).

Misfire:
A misfire may be caused by faulty electrical components,a defect within the air induction ,fuel delivery,or exhaust systems, or by mechanical component failure.
We have both advanced and basic test equipment which can aid the technicians diagnosis and rectification of these faults.

Lack of Performance, excess fuel consumption, etc.
Can be caused by items requiring minor adjustment and routine maintenance due to wear, or by component or circuit failure.
We have a wide range of test equipment to aid further diagnosis & repair.

Typical engine management parameters that can be checked using a scantool

Read ECU identitity	Software version . Hardware version.
Immobiliser Key code	Check the immobiliser key code has been received by the ECU
Fault Code Display	Read Historical & Current fault codes stored in ECU memory. Erase fault codes.
Throttle position sensor	Check range from Zero to Full throttle using dynamic data will display if the potentiometer track is faulty. Check output voltage.
Engine Rpm signal	Verify signal received from the crankshaft position sensor during cranking and engine running. Most vehicles crank at around 200rpm when the starter is operated which can be verified using the 'live data'function of a scan tool.
Camshaft Sensor	The Camshaft position sensor is often used for cylinder identification on sequential fuel injection systems. The cam sensor signal may control the timing of injection.
Battery voltage	Check battery voltage. Switch on loads such as headlights / fan / heated rear window and check battery charging voltage is maintained.
Coolant temperature sensor	Verify the coolant temperature sensor reading as seen by the ecu when the engine is cold, during warm up, and at normal operating temperature.Coolant temp sensors are normally of negative temperature coefficient type , ie, resistance decreases as temperature increases.
Intake air temperature	Verify the intake air temperature sensor reading .Air density changes with temperature. Intake air temperature is used to correct fuel injection duration to aim for stoichiometric combustion and greater fuel economy..
Mass Air Flow sensor	Observe dynamic data to verify operation of the Mass Air Flow sensor at different engine rpm . Check airflow increases as the rpm increases.
Manifold Absolute Pressure	Check the engine vacuum at closed / open throttle and when engine is under load. Problems with this sensor can be caused by blocked or split pipes.
Boost pressure	Check output boost pressure of the turbocharger, boost pressure sensor reading. Low boost pressure readings can be caused by a worn turbocharger,or wastegate stuck due to faulty control solenoids or vacuum circuit. Many engine management systems provide a 'desired boost pressure reading' and an 'actual boost pressure reading'.
Lambda (Exhaust gas Oxygen) Sensor	Check that the Lambda sensor switches from Rich to Lean and vice versa as the engine runs at normal operating temperature. Check milli-volts output using dynamic data display. Where lambda sensors are fitted before and after a catalytic converter, the first sensor will be correcting engine fuelling (expect a switching signal) and the post catalytic sensor should have a steady signal to indicate the catalytic convertor is working.
Feedback control	Check engine management is in open loop control at cold start and moves to closed loop (lambda sensor feedback ) status when at normal operating temperature.
Injector duration	Check opening time of injectors at cold start, during warmup, and at normal operating temperature.The longer the injector opening time the more fuel being delivered.
Fuel pump relay status	Monitor whether fuel pump relay is on / off. A relay low voltage or open circuit fault may indicate a broken wire or coil fault
EGR system status	Exhaust gas recirculation control. EGR system faults often occur due to carbon build up causing restricted operation.

Fuel pump relay	Turn on / off
Idle air control valve	Operate. Removal from the throttle body can allow carbon deposits to be cleaned from the IAC using solvent cleaner whilst operated by actuator test function.
Stepper motor	Activate stepper motor to verify operation and wiring continuity.
Cooling fans	Switch on / off low and high speed cooling fans to verify operation and wiring.
Coil driver test	Verify the operation of ignition coils by operating using test spark plugs
Injector test	Turn fuel injectors on / off to verify electrical operation. On some systems this function may be carried out whilst the engine is running to enable power balance testing and help identify faulty cylinders.
Solenoid test	Activate items such as Exhaust gas recirculation solenoid and canister purge valve solenoids to verify wiring and operation.
Reset Service Interval	Reset dash inspection and service lights. Reset service mileage countdown values.

Routine Tune Up:

This may include a scan tool test for stored fault codes. Just because the check engine light is not on does not mean there are no stored fault codes or malfunctions.
A visual check of vacuum hoses ,wiring and spark plugs can also reveal maintenance required.
Routine replacement of service items such as Air filter,Fuel filter,Spark plugs,may also bring benefits.

Click here for more information about fuel injectors

The table below is a rough guide to computerised engine control strategy. All values are approximate and will vary from vehicle to vehicle.

Engine Cranking during cold start	Coolant temperature below 20 degrees centigrade	Rich fuel mixture achieved by opening injectors for longer duration	System in open loop status using pre programmed fuel settings based on temperature and airflow
Engine started and running in warm up phase	Coolant temperature between approx 20 and 70 degrees centigrade. Alternatively mode may be based on a time value since engine start up.	Injector duration maintained to provide a slightly rich mixture to prevent stalling	System in open loop status with fuel delivery computed from mass air flow,temperature and manifold absolute pressure.
Engine at operating temperature	Coolant temperature above approximately 70 degrees centigrade	Average injection duration reduced to provide a leaner mixture for fuel economy	System switches from open loop control in to closed loop control mode. Change over can be a programmed function of coolant temperature and Exhaust gas Oxygen sensor (lambda sensor) voltage signal indicating a rich mixture status at least once. Exhaust gas Oxygen content is monitored (lambda sensor switches rich...lean...rich etc...)and signal feedback processed by ecu to adjust injection duration to acheive best combustion of air fuel mixture.
Hard acceleration or heavy engine load	Driver demand monitored at throttle position sensor. Engine load monitored at Manifold absolute pressure sensor.	Injector duration increased to provide fuel enrichment . Engine produces more torque for acceleration.	Engine control computer may switch into open loop control mode during acceleration.
Deceleration	Throttle position sensor signal indicates reduced demand.Engine at normal opeating temperature.	Air fuel ratio increased to reduce emissions of hydrocarbons and carbon monoxide. (Less fuel)	Feedback control status may be in open or closed loop mode depending on program of engine controller.
Engine idling	Engine temperature normal.Throttle postion monitored or idle switch closed.	Exhaust gas recirculation on to reduce emissions. Injection pulse width controlled by ecu to provide efficient fuelling, and idle air bypass controlled to maintain 800 to 900rpm and prevent stalling.	Closed loop control status, Injection duration controlled based on input signals from exhaust gas lambda sensor.

West Mercia Mechanical Services,
10 Arrow Road,
Telford.TF5 0LF.
United Kingdom.
Telephone: 01952 247007
Mobile: 07703 558610