Aftermarket April 2022

BY Ryan Colley, Elite Automotive Diagnostics I hope you have been enjoying these recent articles. I would like to discuss something a little different with this issue’s case study, which will go into detail about computer cloning and in- depth electronics. Developing a diagnostics game plan I would like to present to you a troublesome vehicle we had in our workshop recently that required us to go above and beyond to repair. The vehicle in question was a 2007 BMW 1 Series with a 2.0 Petrol gasoline direct injection (GDI) engine. The vehicle was brought into us after having recently having the coils packs, spark plugs and injectors replaced to try and rectify the issue with this vehicle. However, the fault remained. The customer advised us the vehicle would run very rough from start-up and would eventually cut out. We started the vehicle, and as the customer had warned, it was running very rough. It was obvious to us it was misfiring on multiple cylinders. A full system scan of the vehicle revealed fault codes relating to injector control circuit for cylinders 1 and 4 or an internal fault to the digital motor electronics (DME) a.k.a the engine computer. This computer oversees turning the injectors on to inject the correct amount of fuel into the engine in order for it to run efficiently. I could clearly tell we had a multiple cylinder misfire therefore it was obvious the next step would be to check these circuits. Please refer to Fig.1. Time to Measure The next step was to check if we had any injector driver activity at the injectors themselves. Therefore, I connected an oscilloscope to injectors 2 and 3, first to attain a known good waveform, before continuing onto the circuits the DME was reporting as being faulty. After checking the fuel injector signal, I found we had good control on cylinders 2 and 3 as we would expect. Therefore, now I needed to confirm we had the same signals on injectors 1 and 4. Once connected to fuel injectors 1 and 4, I found no injector driver signals being present. This can be caused by the injectors themselves, faulty wiring or a faulty engine computer injector driver. This meant I now needed to confirm the injectors themselves were not shorted before moving onto check the wiring integrity. Please refer to Fig.2 and Fig.3 I checked the resistance value of the Piezo stack within the injector as pictured in Fig.4. The value I would expect to see would be between 180-195k ohms. This is an indicator of a good Piezo stack, meaning electronically this injector is not shorted. As you can see from the image, we have 193k ohms, which is within the range I would expect 36 AFTERMARKET APRIL 2022 TECHNICAL www.aftermarketonline.net ATTACK OF THE CLONES A troublesome BMW 1 Series that received some attention from Ryan recently showed how cloning is the future to see on a Piezo injector. I confirmed all four injectors were the same resistance value indicating the injectors was not the issue next, I took the same measurement as above directly at the ECM. However, I still did not have any injector driver control. It was now obvious the engine computer was at fault. How do we solve a hardware supply issue? After contacting our local dealer to order a replacement engine computer at a cost of £1,200+VAT, I was informed they currently had none in stock and did not have an estimated time of arrival on any new ones due to a chip shortage. This then only gave us one other option which was to clone the engine computer data into another engine computer from a donor vehicle. This process is called cloning. The process is done using a specialist programmer, which will read the microprocessor and EEPROM internal to the engine computer to retrieve all the data required to transfer into the donor unit. This is done by directly connecting to the engine computer and manually powering the unit up on the bench. The data retrieved contains immobiliser information as well as the engine computer’s software and programming data effectively producing an identical match to what was previously installed on the vehicle. With this information we can make clones of the original which can then be installed back onto the vehicle. Please refer to Fig.5 and When parts are no longer available, we need to think of effective methods of repair which will not only correct the issue, but will also result in a long-lasting repair ”