@theoneandonly @Fredastaire @MarcoWuerttemberger @Canoeing camper
Hello all, I think it would be worthwhile to discuss the parameter preferences that are best suited for diagnosing a blocking LPEGR cooler.
We have two suggested parameter lists before us. There is the original “Template No. 7” created by Theoneandonly, and there is the other refined list which I have suggested to use.
Both use the maximum number of 26 parameters that can be graphed and contain 21 identical parameters. The only difference is the remaining 5 parameters. The parameter list I suggest is based on the original “Template No. 7”, but with refinements that are more suited to the problem at hand.
We are trying to capture data that will help in diagnosing a blocking cooler.
Let us analyse the differences between the two parameter lists to determine the best suitability for the task at hand.
Template 7 includes the Odometer. This has no bearing on any outcome.
It includes Injection Fuel Quantity (Post) which will only be active during a DPF regeneration and not required for this specific test.
It includes the Particle Filter Temperature which is not required as we are already recording two other more important exhaust temperatures – but is specific if we were interested in recording the temperature during a DPF Regeneration.
It includes the Particle Filter Clogging which is not required – we are already measuring the DPF Differential Pressure sensor – it might be of interest if we were recording a DPF regeneration.
It includes the Distance from last DPF Regeneration which has no bearing on the outcome of this specific test.
So, the above 5 parameters are more aimed at capturing data applicable to a DPF Regeneration recording, but not for a blocking cooler.
The 5 parameters that I have replaced them with in the refined list are targeted at the suspected fault – being a blocking LPEGR cooler.
The first one is the Battery Voltage. Note that this is not a measurement of the starter battery at the battery terminals, but the actual supply voltage at the input connector of the ECU. And this is important to look at because if there is a supply or earth cable impedance issue then this parameter will be affected and can have many consequences in any test.
The second is the Turbo Actuator Command – this is absolutely critical to monitor as it has a direct effect on the engine performance.
The third is the Vehicle speed and this is important to help understand during the analysis of the data of the actual vehicle operating conditions during the test run.
The fourth is vital – the LPEGR Target Position, as without this parameter we cannot be sure if the Actual LPEGR valve position is correctly tracking where the ECU is commanding it to be.
The fifth is the Lambda Oxygen Concentration (after DPF). This may not be totally necessary as we are already monitoring the upper one, but it will affect the outcome if it is not correct – so worth adding in as the last of the 26 possible parameters.
To summarise, Template 7 is OK, but includes parameters which are not as well targeted and includes a few parameters which are more suited to the analysis of a DPF Regeneration at the expense of missing some very vital parameters.
The refined parameter list does just that – it refines the targeted parameters to be more specific to the task at hand and improve the likelihood of a successful analysis.
I would like to be clear here, I have no ownership issues, and my pride will certainly not be dinted if my suggestions are howled down or ignored. I am suggesting that it may be time to replace Template7 with the revised Template for future diagnosis purposes. I know from experience that by using the revised template and using a holistic approach to the data analysis, it has proved successful particularly in those more difficult cases where the LPEGR cooler was becoming marginally blocked, but not yet fully blocked.
Before the test is recorded, it is important to look at the Particulate Filter Clogging to make sure it is not approaching 100% as the test results will be invalid if a DPF Regeneration occurs during the test run (DPF Regeneration trigger is 100%).
And as already specified, the test should begin with a cold engine and drive normally until the engine is warm and stabilised – a good 20minutes to half an hour run and with speeds up to the maximum legal on open highway and also try to maintain sections of constant speed and gas pedal opening. After the engine has warmed up it is also important to include a couple of full 100% gas pedal accelerations, say in fourth gear starting from 2,000 RPM to 3,500 RPM. This application of full accelerator pedal will trigger the ECU to close both the HPEGR and LPEGR valve and thus take their influence out of the equation. It is an important part of the test analysis. From experience, the fault is often triggered on a cold engine warming up, with light to medium gas pedal opening.
Note the revised template has two slight variances. The one supplied is for the 130HP engine, there is another (already documented) for the 150HP and 180HP engines as they have the added advantage of having the VGT turbo which includes the measurable feedback servo mechanism.
Up to you John, but I urge you to update your Template 7 to the revised list.
As we all know, there are other parameter lists for recording DPF Regenerations, and more importantly to the Blocking Cooler Syndrome – the Injector Correction Values. They can easily be done as a separate test.
