Understanding AFR: The AFR Target Map
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The AFR Target Map
01.47
| 00:00 | So far we have discussed how the AFR will effect the performance and tuning of the engine. |
| 00:05 | In this next section we are going to look at how we can bring this together throughout the engine’s operating envelope. |
| 00:12 | We do this with an AFR Target MAP. |
| 00:16 | The AFR target MAP is really just a 3D table of load vs RPM that matches the same break points that we have used in the main fuel table. |
| 00:25 | This gives us a table that we can fill in with our desired AFR targets for different areas of the engines operation. |
| 00:33 | We are going to be using this map when the time comes to actually tune the car but before we get that far, we are going to spend a little time and break the engine operation down and discuss each section in detail. |
| 00:47 | Here you can see an example of an AFR target MAP. |
| 00:51 | We have RPM on the x axis and load in manifold pressure on the Y axis. |
| 00:57 | In this case the load increases as we move up the table but some ECUs work the opposite way and load increases as we move down through the table. |
| 01:06 | This should be pretty obvious by looking at the numbers on the load axis. |
| 01:11 | You can see that we have highlighted areas on the map to represent idle, cruise, high rpm vacuum, and full load n/a which also corresponds to a zone known as transition for turbocharged or supercharged engines. |
| 01:27 | As we move into positive boost pressure we have two zones labelled medium boost and high boost. |
| 01:33 | You can see we also have a couple of dead zones, and finally the starting zone. |
| 01:39 | We will look at each one in some detail and discuss what we need to focus on when tuning them. |
