There are plenty of pitfalls awaiting a technician when carrying out fuel injector replacement. At first just getting the high price of the repair over the line seems like the biggest problem. But wait … there's more hiding in that engine bay!
Leaking injector sealing washers provide a fairly decent challenge to overcome. The escaping carbon gets baked by engine heat and seems to be harder then concrete inside an already tight fitting injector cavity. Clean up of the injector seat with correct seat cutting tools is critical to achieving a long lasting seal. Along with that is the condition of the injector clamp down fork (sometimes replaced with injector), hold down bolt (often a single use only torque to yield type) and hold down bolt thread, which on some brands is fragile requiring helicoils. This is often discovered during torquing down the final stage of the injector torque sequence.
Putting aside the financial and mechanical side of things leaves us with the final step of the job. The entering of the flow rate calibration numbers or injector coding as it is commonly known.
Extremely precise quantity AND timing of fuel delivery is required by modern engines to get the most out of as little fuel as possible while also ensuring parameters are kept within, to keep exhaust emissions as low as possible.
Launch Auscan injector coding data Ford
Fuel injectors are produced in large scale production lines to get costs down towards what an end consumer can afford to pay. The manufacturing variations are accounted for with the injector code numbers. These numbers inform the engine ECU of what the fuel flow rate is on each fuel injector. But of equal importance is the response time of each injector. Not every injector discharges fuel in the same amount of time once activated. The electrical side of the injector also has variations that need to be managed. Differences in this time if not compensated result in variations of fuel injection timing ie a slow injector injects many crankshaft degrees behind a faster responding injector. Without compensation the engine could be very unbalanced during operation, knock excessively, possibly suffer mechanical damage and produce high exhaust emissions which overload exhaust aftergas systems.
This is why we must enter the injector code numbers accurately as shown on the injector or calibration certificate with injector. Care must also be taken to ensure the injector is located in the correct cylinder number and is not mixed up during installation.
This final step should be the easiest. Enter a few numbers, sometimes as many as 30 digits and job done.
Jaltest diagnostics read out of 30 digit Hino injector codes
There is at times confusion mixed with frustration when the new injector codes are not accepted and written into the memory of the engine control unit. We come across these issues in our technical support service.
A fully charged, healthy battery with battery stabiliser is an important first step. This process can take a reasonable amount of time if long code numbers are being entered. .
Now we need to confirm a tool, vehicle, operator or parts issue. A simple method we commonly use is to program existing injectors into an adjacent cylinder. If the injector is switched into another cylinder without any issue we know we have a operator or part compatibility issue. Next we can retry coding in a new injector code and checking that we have all digits correct. It is not difficult to enter a letter instead of a numeral in the code string. For long codes it is often best to have two people carry out the process.
If we are still not getting out injector codes accepted, it is time to have a deeper look into parts compatibility. Incompatible numbers not expected by the engine control unit will not be stored. Correct parts for your engine are required.
Tool or vehicle faults are not very common but possible. Having a large network of support clients alerts us if any issues occur fairly quickly, we get complaints. It also gives us access to check other operators if they have had issues with procedures or even get the process tested on another vehicle for functionality.
Injector replacement when required is a costly exercise. It does come with an incentive for the vehicles owner that as the injector discharge nozzles erode from passing fuel, causing overfuelling of the engine by as much as 20% on worn injectors, some pretty good fuel savings will be possible and also a lengthening of the life of the exhaust aftergas systems as well.
https://www.aecs.co.nz/shop/product/778360/launch-auscan-4-scan-tool/
aecs.co.nz/shop/product/879342/launch-pfp-150-diagnostics-and-programming-battery-charger/
