Practical Standalone Tuning: Step 6: Idle Tuning
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Step 6: Idle Tuning
05.09
| 00:00 | Alright, we've got our engine up and running, it's idling quite happily here, but before we actually move on and start tuning, and this would be before we even go near the dyno, there's a couple of checks that we want to make just to essentially ensure that everything is mechanically sound and we're not going to face any problems that could waste time and money once we actually get to the dyno. |
| 00:18 | So, specifically here, one of the checks we're going to make is to ensure that our alternator is charging. |
| 00:24 | The number of times I've seen this is actually quite ridiculous. |
| 00:27 | We can get the engine up and running, but the alternator isn't charging and if we start trying to tune the engine, obviously the battery voltage is below where we need it to be so, the tuning that we're going to perform may be inaccurate once the alternator is charging and of course it's not going to take too long before the battery's too flat to run the engine, so really important just to check that. |
| 00:47 | And we can do that simply by checking the battery voltage which we can see here being displayed. |
| 00:53 | Now, the battery voltage typically should sit in the 13.8 to 14.2 volt vicinity once the engine's up and running and of course ours sitting right on 14 volts is in the middle of that range, so we're comfortable with that. |
| 01:06 | If we have an oil pressure sensor on the vehicle, then we also want to check that our oil pressure is at least in a suitable range. |
| 01:14 | For a cold engine that's just started, we may see the oil pressure between maybe 50 and 80 psi at idle, at a hot temperature, that might be in the region of about 15 to 25 psi at idle, so obviously just mechanical checks to make sure that the engine is actually healthy. |
| 01:31 | The other thing we can do at this point is now come back and revisit our base ignition timing, remember this is set in two stages, now that we've got the engine up and running, we can get a better idea of where that base ignition timing actually is and fine tune that as accurately as we can. |
| 01:47 | We want to do this at between about 2000 and 3000 RPM and because we've only made block changes at the moment out to 2000 RPM and we're not there, we're at 1000 now, it's likely we may need to make some block changes to our fuelling in that region just so, the engine is happy idling out there, let's just have a quick look and see what that might look like, so I'll just use a bit of throttle here to bring the RPM up. |
| 02:11 | And as we do this we'll look at our lambda and unsurprisingly it has gone a little bit idling, it's actually not too bad, but again we can just use the page up there to get us back on our target, we can see how quick and easy that is. |
| 02:22 | So, now we're out at 2000 RPM, that'd be a reasonable place to set our base ignition timing. |
| 02:27 | The other thing we want to do is just confirm that the engine is capable of idling at a sensible RPM. |
| 02:34 | Now, why I say this is because it's very easy to have cam timing that's maybe a tooth out, the engine can still run, but you might find that you just can't get the engine to idle at a sensible RPM. |
| 02:46 | So, if we know the cam's a stock then we know for our 4G63 here, we should probably be able to make it idle quite happily at maybe 800 to 900 RPM. |
| 02:56 | If it's a bigger capacity V8, maybe 650 to 700 RPM would be typical. |
| 03:01 | So, if we can't do that, if the engine's constantly hunting and then stalling, we don't have much manifold vacuum, that would be an indication that our cam timing could be out. |
| 03:11 | So, here we can see we're comfortably holding an idle at 1000 RPM and we're at minus 60 kPa. |
| 03:18 | So, yep that's pretty healthy numbers for a stock 4G63 like this. |
| 03:23 | Caveat here is if you have got an engine that's fitted with a very aggressive cam or camshafts with a lot of duration and overlap, then all bets are off. |
| 03:31 | In that case, for our 4G63, we may need to raise the idle speed to 1000 or even 1100, 1200, depending how big the cam is in order to make the engine idle happily. |
| 03:42 | And we can waste a lot of time trying to make the engine idle at an unrealistically low RPM. |
| 03:47 | What I'm gonna do as well is just make sure that our idle control circuit is functioning. |
| 03:51 | I'm not going to go too deeply into this, again trying to keep this worked example relatively simple and based on just our fuel and ignition and boost. |
| 04:00 | If you do want to learn more about idle tuning, you can check our webinar archive for webinars on that topic. |
| 04:07 | So, if we come into our engine functions here and we come down to our idle control, what we want to do at least at this point is make sure that we are in open loop, so that the closed loop control system isn't working in the background to kind of fix any errors that we've got. |
| 04:21 | So, what we can then do is come into our base open loop table here and at the moment all I want to do is just make sure that the idle control system is working. |
| 04:29 | So, I'll just use page down here to remove a few percent from, or a few steps I should say, out of our base table and just make sure that yes our idle speed is adjusting in line with that. |
| 04:41 | We'll get it down to now 850 to 900 RPM, it's running really happily. |
| 04:46 | We've got a little bit rich here, but again I'm not too worried about this at the moment. |
| 04:50 | So, at this point I'm comfortable that my idle speed control is working, I'm comfortable that the engine is mechanically healthy. |
| 04:56 | I'm finally ready to bolt the car onto the dyno or strap the car down on the dyno and confident that we can actually get stuck into our tuning. |
