A little while ago we posted a brief article on response time and why it matters. This short and sweet article had some insights on why we care about response time so much and why, even when you have equipment with a lot of different test steps and amazing functionality, it is important to not forget the basics; such as response time. This is why we are dedicated to Full Event Response Time (FERT)
Welcome to FERT
The ‘full event’ part of FERT refers to the sequence of tests you can carry out with an injector to test the whole injector from initial delivery to injection event.
An injector contains multiple internal mechanisms. An electrical drive, a valve, a spring mechanism, and the point of injection at the nozzle. It is possible to measure the response time of all these events.
The ‘response time’ part refers to the speed at which this measurement is recorded. If any one of these operations was affected then different symptoms would be present on the vehicle. If these events within the injector happened too slowly the vehicle may experience lack of power, high emissions, or a cylinder imbalance.
Alternatively, injecting too early can lead to knock, excessive heat, or piston crown damage and much more. Response time absolutely needs to be a fundamental of injector testing in order for correct diagnosis and correct repair of the injector.
Not all injector test benches test in this way. Some competitor solutions simply test the electrical drive and value response. This approach is sufficient if you suspect these parts of the injector are faulty but it would have no way of informing you about any of the other critical components of the injector.
You would be simply not testing the whole injector. It could leave a technician no better informed than before he began the test, and could result in the wrong course of action being taken.
Hartridge see the ability to test the whole injector as elementary. The Sabre CRi Master measures the response time of the electrical drive, the value, and the nozzle and the injection opening time.
Thanks to FERT a technician can get a full picture of the health of the complete injector. We are also able to carry out superior measurement of this response time. The nozzle chamber and controlled counter pressure of the Sabre CRi Master give the ability to measure response time as low as 400bar at 5mm/str resulting in a powerful and trustworthy interrogation of that injector.
Here at Hartridge, we believe that any less than this would be missing fundamental injector testing capability.
Testing again and again.
As fantastic as FERT is, it would be useless if a technician wasn’t able to repeat the test results for that injector. They may want to run the test a couple of times in case the injector was on the limits of it’s tolerances and they will want to test the injector after repair or refurbishment to confirm the performance of the injector is restored.
In a 2016 paper in the journal Combustion Engines repeatability of results when testing an injector was central to their investigation of direct injection in spark ignition engines.
After all, this is exactly how an injector must behave within the combustion process-needing to consistently and reliably inject fuel repeatedly.
In the Sabre we have designed a tuned delivery chamber to provide stable and accurate repeatability with increasing rail pressure as well as repeatability at the lower end of available bar pressure.
Response time thresholds can be configured to suit the test conditions of the injector e.g. to replicate a scenario that you suspect may be happening within the vehicle and replicate the fault within the injector.