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Practical Standalone Tuning: Step 6: Idle Tuning

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Step 6: Idle Tuning


00:00 - OK so before we go too far into our tuning we want to have a look at the idle setup and make sure that we can get our engine idling stably and again we've got an engine that in essence has already ben tuned.
00:11 So the settings that are kind of in the background here of the ECU are already reasonably close, I just wanna go through that setup and show you how it works.
00:20 Now if we go to the idle speed control menu, you can see all of the settings here that are relevant.
00:25 Now the idle speed control mode tells the ECU how it's going to control idle speed.
00:31 So it's gonna depend if you're using an idle solenoid or a stepper motor.
00:35 Now in this case we've got E throttle, electronic throttle body control for idle speed.
00:41 So the ECU is physically opening and closing the throttle butterfly to control idle speed.
00:47 I've got that set up in open loop at the moment which means that the ECU isn't making any adjustments and there's no feedback loop going on in there.
00:57 We wanna get the engine idling smoothly in open loop mode before we go any further.
01:02 We've got our target idle RPM table down here and again as we discussed, we want to make sure that the numbers in this table are fairly realistic for the particular engine that we're running.
01:16 So in this case let's say from 60 degrees up, we want to target an idle speed of 1000 RPM.
01:24 And then at 20 degrees and below, 1200 RPM, and then we can just interpolate in between those points and get a nice smooth curve.
01:36 So the way the idle speed control system works in the Link G4 software is that is uses a idle base position table and this is basically the amount that the throttle body is open.
01:50 So if we for instance increase the throttle body opening, you can see down here that our idle speed increases and we can close it down and you can see that it decreases.
02:04 Now for some reason with this particular engine, you can see at 90 degrees, which we're almost up to, we're actually now have the throttle body completely closed and our engine RPM is sitting at 1200 so we're actually 200 RPM above our target.
02:21 For a road car that would probably be something we'd want to look at a little bit further because we don't really want the engine idling that high.
02:29 In this instance it's a race car and it doesn't really matter.
02:32 But what I'd be looking at there is a possibility for a vacuum leak or something else that's bypassing air around the throttle body.
02:40 Or if there's another idle circuit that's active that is bypassing that air around the throttle body and keeping the engine running faster than we want.
02:50 So for a road car we'd definitely wanna chase that down and get our idle speed down where we want it to be.
02:55 As I said, this is a race car so we're not really too worried.
02:58 I just want to show you the system, show you how it works and give you some explanation of what I would do to adjust it.
03:05 So once the engine is fully tuned, we'd wanna revisit this particular table here from a cold start and we'd want to set each of the cold start steps or coolant temperature steps down at 10, 20, 30, 40 degrees, and that's just going to get our engine idling nice and smoothly on the target RPM as it warms up.
03:28 So once that's all done then we can convert it back to closed loop control and that let's the ECU take care of any little idiosyncrasies or differences between target and actual RPM.