Road Tuning: Idle Control Settings
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Idle Control Settings
02.44
| 00:00 | Once you have the idle ignition and idle mixture under control, you'll need to make adjustments to the idle speed control settings in the ECU. |
| 00:08 | This includes idle ups for cold starting, air con inputs and power steering. |
| 00:14 | All of this aims to keep a smooth and consistent idle speed with no stalling. |
| 00:20 | This is actually one of the most time consuming parts of any tune, as we want to try and replicate the idle control of a factory car. |
| 00:28 | It also requires the idle speed control to be adjusted at a range of temperatures to ensure a good cold start performance. |
| 00:36 | Every ECU deals with idle speed control differently and it also will depend on the type of idle control system fitted to your engine. |
| 00:45 | The way we deal with it is the same for all systems though. |
| 00:48 | We start by choosing a realistic idle rpm target for the engine. |
| 00:53 | This is usually a 2D table, and we'd expect the idle speed to be around 200-300 rpm while at cold start temperatures of 10-20 degrees. |
| 01:03 | One mistake that I often see is people trying to make an engine idle at an unrealistic rpm. |
| 01:09 | For example, most small displacement four cylinder engines will idle happily at around 750-950 rpm. |
| 01:16 | If we try to make these engines idle at perhaps 650 rpm, which might work well for a large V8 engine, we'd have trouble with poor running and stalling. |
| 01:26 | Once we have set the total idle speed table, we need to disable close loop control if it's being used, and set the base idle position table so that the idle speed closely matches our target across all operating temperatures. |
| 01:41 | This needs to be done from a cold start, and normally I'd do this test once the rest of the tune's complete. |
| 01:48 | When the base position table is tuned, we can enable close loop control. |
| 01:53 | This lets the ECU adjust for any discrepancy between target idle speed and actual rpm. |
| 01:59 | A tip here is if you find the rpm drops a little low when you rev it up and back off the throttle, try increasing the base idle position a couple of percent. |
| 02:09 | Depending on your ECU, you may also have adjustments for various idle ups and control of how aggressively the close loop control will chase the target rpm. |
| 02:19 | These settings will require adjustment by trial and error until your idle speed control is accurate without any hunting or oscillating. |
| 02:28 | So by the end of this module, you should know how to set your mixture and ignition timing at idle, how to spot any potential mechanical problems, and how to adjust the idle control settings in the ECU. |
