EFI Tuning Fundamentals: Fuel and Ignition Tables
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Fuel and Ignition Tables
02.24
| 00:00 | - Now that we have a better understanding of what inputs and outputs are available to the ECU, let's have a look at how we, as tuners, can actually talk to the ECU and adjust it to get the results we want. |
| 00:11 | While every brand of ECU has its own unique software, the principles remain the same so let's have a look at the most common tables. |
| 00:19 | While there are a lot of similarities in how we address the tuning in aftermarket standalone ECUs, reflashing an OE ECU can vary a little more and we'll address this in a separate module, shortly. |
| 00:30 | The first table we're going to look at is the fuel table. |
| 00:33 | This is where we're going to be spending a lot of our time tuning because it tells the ECU how much fuel needs to be injected to achieve the correct air fuel ratio. |
| 00:43 | This table is 3-dimensional with engine RPM on one axis and engine load on the other. |
| 00:49 | The load signal will depend on the sensor we're using here. |
| 00:52 | As we saw in the EFI Components module, options include MAF, MAP or TPS data. |
| 00:58 | Now we have a table which represents the full range of the engine's operating envelope, everywhere from cranking and idle through to maximum power and maximum RPM. |
| 01:08 | This lets us very accurately adjust the required fuel injection in each zone to get whatever air fuel ratio we have decided on. |
| 01:17 | The other table we're going to spend a lot of time tuning is the ignition table. |
| 01:20 | This is similar to the main fuel table, but this time it includes the ignition advance angle in crankshaft degrees. |
| 01:27 | This represents the point in the engine cycle that the spark plug will fire and initiate combustion. |
| 01:33 | We're going to learn more about ignition timing and how to tune this a little later, so you don't need to worry much about it right now. |
| 01:40 | The numbers in the ignition table are degrees of crankshaft rotation relative to TDC on the compression stroke. |
| 01:47 | Typically, we'd have the ignition event occur before the piston reaches TDC and this is represented by a positive number in the table. |
| 01:55 | In some unique situations, we may want to have the ignition event occur after the piston has moved past top dead centre and this would be represented by a negative number. |
| 02:05 | So now, you should be familiar with the two tables that you're going to spend the largest portion of your time working on when you're actually tuning the engine. |
| 02:13 | Of course, there are a number of other tables, as well, that will make compensations to both of these tables and we'll be looking at these shortly. |
