Road Tuning: Compensation Tables
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Compensation Tables
02.41
| 00:00 | Most ECUs will provide a range of compensation tables that the tuner can use to keep the engine running consistently across a wide range of atmospheric conditions. |
| 00:10 | These compensations may include engine temperature or warm-up enrichment tables, intake air temperature compensation tables, and individual cylinder trim tables. |
| 00:20 | Often these tables will be available for both fuel and ignition compensation. |
| 00:25 | Tables such as the warm-up enrichment will need to be tuned after the rest of the engine has been properly mapped, but the important point at this stage is to make sure that we don't have any weird or unusual compensations going on that could affect our tuning. |
| 00:42 | By this I mean we need to go through the different compensation maps and make sure they are zeroed in the areas that the engine will be running at normal operating conditions. |
| 00:53 | Also check that any individual cylinder trims are disabled. |
| 00:57 | This shouldn't be an issue if the ECU is brand new, but if you are using an ECU that has been tuned previously, it pays to make sure that the last tuner hasn't done something weird. |
| 01:09 | Intake air temperature correction is a table many people struggle to tune properly. |
| 01:14 | The ideal gas law that we learned about back in the EFI Fundamentals Course shows how air density varies as temperature changes. |
| 01:22 | From this law, we found out that the air density changes by around 2.5% for every 10 degrees change in air temperature. |
| 01:32 | Keeping this in mind, we want to set up an air temperature correction table which trims the fuelling by the same amount. |
| 01:38 | We want the correction to be zero at the standard air temperature of 20 degrees. |
| 01:45 | As temperature increases, we reduce the fuelling by 2.5% every 10 degrees, and as temperature drops we increase the fuelling by 2.5% every 10 degrees. |
| 01:57 | To reduce the effect of heat soak, I usually set this table up as a 3D table with throttle position on the load axis. |
| 02:04 | I use this axis to reduce the amount of influence the table has at closed throttle. |
| 02:10 | You can see this in an example table here, which I find works well in most situations. |
| 02:16 | So by the end of this module, you should have an understanding of what input to use for the load axis on your tables, how to configure the axis, and what numbers to enter into the maps to get the engine started and running. |
| 02:31 | You should also understand how to zero the compensation tables and how to adjust these to suit. |
