Repairing vehicles today involves more than just replacing a damaged component and sending the car back out to its owner as many new parts need to be coded to the vehicle to complete the job.
Our latest technical article by Damien Coleman shows you how Snap-on diagnostic software makes this process simple.
We’re looking at a 2008 BMW E90 with a 2.0L spark ignition engine that has been suffering from occasional rough running when starting and the engine management light is illuminating.
An initial scan found fault codes highlighting combustion misfires on cylinders one and four, although once an ignition coil had been replaced on cylinder one the vehicle ran as normal for a few days, until more problems arose, and a cylinder four misfire was detected.
After investigation, the cylinder’s injector was replaced (click here if you'd like to read the full details on the diagnosis and replacement procedure) and had to be coded to the vehicle in order to complete the repair. The steps below were taken using a Snap-on VERUS Edge car diagnostic scan tool to code the injector:
- Select Special Functions from the main menu, then press Injector Coding
- When asked whether a new engine ECU was installed, select No
- The code for the new injector can be found just below the electrical connector – in this instance 566217 – so enter that code at the next screen
- The next screen displays the old and new codes, so if the new code is displayed correctly press Program
- At the next screen, press Continue to confirm successful programming of the new injector code and it is then displayed along with the vehicle’s other injectors
After the injector was fitted and coded the fault codes were cleared. The spark plugs, engine oil and filter were replaced due to the unmetered fuel entering the cylinder. The fuel system was tested again and returned the following results:
|Injection Duration Cylinder 1
|Injection Duration Cylinder 2
|Injection Duration Cylinder 3
|Injection Duration Cylinder 4
The final test to validate the repair was to monitor the output from the low- and high-pressure fuel pressure sensors. A third channel was used to monitor the current flow through the fuel pressure control solenoid mounted on the high pressure pump.
- Yellow trace: Fuel pressure sensor – high pressure
- Green trace: Fuel pressure sensor – low pressure
- Blue trace: Current flow through fuel pressure control solenoid
The above waveform is correct for this engine operating condition (warm and idling).
Date posted: 23 January 2017