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Practical Standalone Tuning: Step 6: Idle Tuning

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Step 6: Idle Tuning


00:00 - We've got our engine running but we're still not quite ready to hit the dyno yet.
00:04 The next step is to make sure that we get the engine to hold and maintain a sensible idle speed.
00:12 This is a great place to show up any potential mechanical problems with the engine set up.
00:17 As as some potential problems with your ECU configuration as well.
00:21 Let's have a look at our idle control parameters here in the Haltech Elite.
00:27 And we are not going to go through every parameter but the key ones here, first of all we have our actual target idlespeed table.
00:36 And this as it's name implies is the idle speed that we would like the engine to achieve.
00:42 You can see in this case we actually have an axis of vehicle speed as well.
00:47 And this allows us to have to idle speed a little bit higher so we don't risk stalling when the engine comes back to stationary after we've been driving.
00:58 As you can see at the moment, we are in the 80 degree centigrade zone and our target idle speed here is 800 RPM.
01:08 It's pretty typical at lower engine speed temperatures as you can see here to target a slightly higher idle speed.
01:15 That's pretty normal.
01:17 And we can see that actual idle speed is sitting really nicely on our target.
01:24 Now in order to control the idle speed the ECU is actually using the drive by wire throttle and we can adjust the amount of throttle opening via the base closed loop table which we can see here.
01:43 The ECU also uses the functionality of ignition correction.
01:48 So this table here, this will define the amount of ignition time.
01:53 And it will be either added or subtracted to the base numbers based on whether the idle speed is above or below target.
02:00 Now, what we are looking for here is first of all, as I mentioned, a stable idle speed.
02:06 Now we are targeting an idle speed, first of all, that is realistic for our 100% stock VQ35 engine.
02:13 800 RPM is the factory idle speed so we can expect to be able to achieve that.
02:19 The engine is a idling stably.
02:21 And at the same time we also can see that the engine vacuum is pulling minus 67 KPA so it's pulling a lot of vacuum, which again for a standard unmodified engine like ours this is what we would expect.
02:36 So the problems we would be looking for here are an engine that won't idle happily at 800 RPM or a sensible idle speed that we've chosen.
02:46 So perhaps in this case we might not have been able to get the engine to idle below 1500 RPM.
02:51 At the same time if the idle with this engine we were only seeing perhaps only minus 20 or minus 15 KPA that's also indicative that there's a problem.
03:02 We may have a manifold vacuum leak or quite likely perhaps the cam timing might be incorrect.
03:09 So those would be key things I would be looking for during this particular phase of the tuning.
03:15 Once we are happy that the engine is idling stably and it is controlling idle speed correctly.
03:21 We can move on actually get the car actually onto the dyno and begin some dyno tuning.
03:28 The reason why we don't want to do this step on the dyno is if we do encounter a problem and we find something that isn't right, then we've already wasted potentially some dyno time and hence some money getting the car loaded up onto the dyno and ready to run just simply to remove it again.
03:45 So it always pays when we actually load the car onto the dyno, we'll turn up to the dyno shop that we know we have a mechanically sound package that's ready to actually begin tuning and isn't going to give us any problems.

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