Mobile Car & Van Diagnostic Service Shropshire & Mid Wales

Warning light on ? Breakdown ? Driveability problems ? Immobilised? Engine Management ecu fault? Electrical fault - Car won't start ? Need repairs ? Private Customers & Motor trade Welcome.
Mobile vehicle computer diagnostic service using professional test equipment and trained engineer.

Engine electrics

Problems with vehicle engine management, fuel & ignition electrical systems may cause

Difficult Starting

Engine Misfire

Intermittent cutting out and stalling of the engine

Loss of engine performance & sluggish acceleration

Engine temperature faults eg, overheating

Poor fuel economy

Vehicle restricted to Limp Home Mode

Check engine light illumination (also known as MIL or Malfunction indicator lamp ) at instrument panel

Engine electrical fault causes

Road salt and moisture ingress to wiring connections leads to corrosion, high resistance, and low voltage faults. Breakage of connection may cause open circuit.

Vibration and flexing of the engine or vehicle body can cause wiring harnesses and pipes to move and chaff against other components rubbing wiring insulation which leads to short circuit, or broken wires (open circuit).

Exhaust emissions and smoke

Reasons for Mot test exhaust emissions check failure may include :
Excessive Carbon Monoxide (CO) content in petrol engine exhaust gas
Excessive Hydrocarbon (HC) content in exhaust gas.
Excessive Smoke emission from diesel car or van.

Excess vehicle exhaust emissions may be caused by

Engine air intake system

including
Restricted air Filter
Turbocharger (if fitted) failure - low pressure - oil leaks into air intake
Exhaust gas recirculation (EGR) designed to reduce exhaust emissions can suffer build up of carbon and sludge deposits in the intake manifold resulting in blockage and restriction of engine air intake components.

Carbon deposits can cause intake system malfunctions such as;
Idle speed control motor sticking
Throttle flap sticking
Exhaust gas recirculation (EGR) valve blocked
Blockage of air pressure sensors eg Manifold absolute pressure sensor (MAP), or turbo boost pressure sensor.
Engine fuelling
Engine component wear
Exhaust component failure, lambda sensors failure including broken wires, catalytic converter, or diesel particulate filter fault.

Driving cycle and Vehicle Maintenance Planning

Vehicle operating conditions including regular journey distance and driving cycle will have a huge impact on the type and frequency of servicing needed.

A vehicle operated on frequent short journeys may not reach normal operating temperature and may also suffer from battery electrical charging system problems.

Manufacturers Extended Vehicle Service Intervals

Manufacturers extend service intervals to reduce fleet operating costs and make new vehicle purchase attractive.

Service Light Reset

Many vehicles are equiped with onboard service indicator lights to prompt the operator when a service or inspection is due.
The service warning alert function is computer controlled and may based on time, mileage, or engine running hours frequency calculation.
Service Light Reset may require a specific procedure or use of diagnostic equipment to reset computer memory.

Engine Control Map Software

Vehicle manufacturers develop generic engine management software for production cars to optimise fuel efficiency combined with low exhaust emissions and driveability over a wide range of operating conditions.
Electronic engine management system software control parameters are stored in the vehicle computer engine electronic control unit (ecu) within EEPROM's as a software 'map'.

Motorsport and performance tuned vehicles may use specialised high performance fuel blends and be designed or remapped with specialist modified engine control software maps written for sports performance to provide increased fuelling and power output often at the expense of driveability.

Performance upgrades may be available which allow specific changes to the original software to meet engine modifications perhaps where aftermarket parts have been added or rework carried out such as cylinder head ported and gasflowed, or flywheel lightened and balanced, to meet individual driving requirements.

Engine control unit remapping may affect the validity of your vehicle insurance - your insurer should be notified of any non standard performance upgrade.

Vehicle Sensors, Actuators, and Signal Processing

Imroved fuel consumption and reduced maintenance are benefits of vehicle computerised engine management through electronic control of ignition timing, fuel mixture, and idle speed.

Diagnostic test scan equipment can read live data and fault codes from vehicle control systems to check operation and vehicle health.

Sensor inputs measure :
Driver demand accelerator pedal throttle position Sensor , Clutch switch, and Brake switch
Engine temperature from coolant temperature sensor and intake air temperature sensor
Engine load from manifold absolute pressure (Map) sensor, mass air flow (maf) and air temperature
Fuelling from exhaust gas emissions (Lambda sensor)
Engine speed, timing and position from carankshaft position sensor and camshaft postion sensors
Vehicle speed from transmission speed sensor or wheel speed sensor.

Input signals are transmitted along wires to a central computer, (ecu) where the received signals are processed and compared to programmed values stored as a memory map, then output values calculated, signals sent along wires to output actuators such as
Fuel injectors
Fuel control pressure regulator
Idle speed control valve
Cooling fan
to maintain performance factors such as smooth engine running, fuel economy, and low exhaust emissions.

Engine management problems ?

A scan tool test to retrieve   fault codes stored as history by the vehicle computer may indicate a component low voltage or open circuit or short circuit code identifying  the area the where a fault exists. Fault codes outputted to the scantool via serial data may be manufacturer specific or generic (EOBD) Taking a typical P0100 fault code as an example, the fault code relates to Mass Air Flow Sensor circuit malfunction. This P0100 code could have many causes for example , broken wiring or bad connection to the airflow sensor, slow response time from the sensor itself, a fault on the engine control unit board causing loss of connection, insufficient air flow past the sensor due to leaking pipework or low performance from a turbocharger. An immediate response from many technicians would be to change the airflow sensor, however, if the fault is an effect of a different cause this would simply be wasted money! Scantools do not fix faults, they read data from the control unit and in some cases have further functions such as actuator testing and adaptation of parameters. Further testing will almost certainly be needed to identify the exact location of the fault if broken or damaged wiring exists.

Fuel Quality

Fuel quality will affect fuel injection system component life.
Moisture (water in fuel) or contamination in fuel can lead to wear and corrosion which will be detrimental to precision machined components in high pressure diesel fuel injection systems such as fuel pumps and injectors.
Wrong refuelling eg putting petrol in a diesel car will contaminate the fuel system and may cause further component damage.
Signs of component wear and failure can include metal particles in the fuel filter or fuel tank.

Manufacturer Software Updates

Manufacturers test extensively whilst developing new vehicle models however unforeseen problems may only show following in service vehicle wear and tear.
Faults affecting exhaust emissions or driveability can sometimes only be corrected be updating the control unit software

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.
Many vehicle software updates may be 'flash' programmed via the vehicle diagnostic connector using a pass-thru (SAE J2534) programming technique.

Updated calibration software is downloaded from the vehicle manufacturers website and transferred to the vehicle computer using the pass-thru interface

Manufacturer Technical Service Bulletins (TSB)

A manufacturer may release information as a Technical Service Bulletin (TSB) if specific recurring faults affect a particular model.
Some tsb information may be restricted to the manufacturers dealer network.

Vehicle Computerised Diagnostics

Mobile service for car electrics repair in Shrewsbury and Shropshire surrounding areas.
Telephone 01743 884888 for booking.

Computerised vehicle diagnostics is a means of using the ability of the vehicle computer control system to monitor  the condition of  vehicle components.

Unsure if you should drive the vehicle with a dash warning light on - We provide a breakdown callout mobile service that travels to you.

Vehicle Fault Codes

A fault code may be generated and logged in a control unit when a system exceeds preset parameters.

Historical fault codes

Intermittent faults which occur during driving may be logged as an historicl error or stored fault code which causes the dashboard warning light to illuminate.

Random disconnecting of electrical connectors in the engine bay may also cause  fault codes to be logged.

Fault code Retrieval

Most modern vehicles require diagnostic equipment with dedicated software to interrogate the relevant control module for stored fault codes.
Automotive  system electrical diagnostics involves an interrogation  scan of the  vehicle computer  for stored fault codes using suitable diagnostic equipment such as a scan tool fault code reader.

Some older vehicles (usually Japanese)  have a self diagnosis function allowing the the fault code to be read by counting the flashes of the check engine light and looking up the value in a reference table.

Autoelectrical Health Check , Test and Repair

Following testing, a faulty wiring circuit may be repaired or component cleaned or replaced.

Diagnostic Equipment Functions

Our vehicle diagnostic equipment is capable of

  Fault code reading

  Actuator testing

to verify wiring circuits by operating the suspect component on a wide range of vehicle systems. The actuator test function can allow some components to be thoroughly cleaned which may save replacement cost.

Programming and Coding

Some components such as electronic fuel injectors , throttle bodies etc may need coding to the vehicle ecu

Advanced system testing can be carried out using oscilloscope signal test methods

Reset Procedures

Following repair work the fault code memory of the vehicle computer will need to be reset to clear stored fault codes.

Vehicle Diagnostic Training

Automotive diagnostics involves extensive technical training and experience combined with complex electrical and mechanical system testing - much more than just plugging in a scan tool to read fault codes.

Diagnostic error codes provide a clue as to what the control system recognises as a fault but remember it is an electro mechanical system which is under repair.

 Motor trade industry experience combined with investment and continuing professional development of staff through a system manufacturer training courses aids vehicle system diagnosis & repair.

Mobile Diagnostic testing available in Shrewsbury, Telford, Shropshire & Mid Wales areas.

Bosch KTS equipment provides control unit diagnosis and multimeter functions

Breakdown callout and diagnostics in Shrewsbury,Shropshire areas.

Vehicle Diagnostic Software Range: