Practical Standalone Tuning: Step 6 : Idle Tuning ( Laptop )
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Step 6 : Idle Tuning ( Laptop )
08.14
| 00:00 | For the next step of our process, we're going to get our idle control dialed in a little bit more finely and just basically make sure that the engine will idle happily. |
| 00:09 | And this is an area which can be easy to overlook where maybe we've got a mechanical problem with the engine, let's say our cam timing's out and we end up wasting a huge amount of time completing the rest of our tune, not worrying so much about the fact that the car won't idle properly and then at the end of our tuning process when we're trying to get the idle dialed in, then we actually stumble upon the fact that we've got a massive mechanical problem which is basically wasted all of the time we've spent with our tune. |
| 00:37 | So, it's really important that we get our idle dialed in and we know that our engine's going to comfortably idle at a realistic engine RPM. |
| 00:45 | And that realistic engine RPM is another really good point to bring up here. |
| 00:49 | If we've got an engine that's got a very very aggressive cam with lots of duration and overlap, then even in a V8 format, trying to make the thing idle at let's say 550, 600 RPM is probably going to be an exercise in frustration. |
| 01:03 | Chances are that sort of engine's going to need to idle at 950, 1000 depending on the spec of the cam, maybe much higher than that. |
| 01:10 | So, we need to be choosing a realistic idle set point. |
| 01:14 | And on that note I will mention that our target which we already set in a previous step of 750, that's probably a little bit higher than we'd necessarily need here. |
| 01:24 | However I do know that with the automatic transmission, because we don't have an idle up when we pull the car into gear, we're going to find that the load of the transmission on the engine is going to pull the RPM down and yes the closed loop idle will fix that but it's going to take some time. |
| 01:41 | So, just to make sure that we don't end up with the idle speed dropping too low as we transition into drive or reverse, that's why I have selected 750, typically this might be quite happy around about 600, 650 or thereabout so really important to choose a realistic target. |
| 01:58 | From there, with the Holley Sniper 2, there's also the process of actually setting up the throttle stop. |
| 02:05 | What we want to do with that is make sure that we've got our throttle stop in a position that it gives the idle air control valve enough room to move, in other words it can both increase and decrease the idle speed as it sees fit. |
| 02:18 | So, what we want to do is jump into our tuning software and we can see down the bottom here I'm sitting in the idle tuning panel with the information relevant to our idle control. |
| 02:27 | And we can see at the moment our engine RPM's sitting around that 750 which is our hot target, we can see that our coolant temp's sitting at 182°F so we are up to normal operating temperature and then first of all what we want to do is take note of this IAC position, that's currently sitting at 16. |
| 02:45 | Now, we want to be adjusting our throttle stop so that the hot, at hot idle, this is sitting between 5 and 15, that's Holley's recommendation. |
| 02:56 | I'm going to basically take a middle of the road approach there and we're going to try and get this sitting around about 10% again, just to give it enough authority in both directions. |
| 03:06 | So, the way we're going to do that, if this is sitting above our target which it is at the moment, remembering we want 10%, so this is opening too far, giving more airflow. |
| 03:15 | So, in order to fix that, what we need to do is open the throttle stop screw or basically turn the throttle stop screw clockwise, that'll open the throttles a little bit by passing more air and that will then bring the IAC position down. |
| 03:29 | We do need to be mindful though as we're making this adjustment and watch the throttle position here, this needs to be sitting below 2% in order to be in idle air control or idle speed control closed loop mode. |
| 03:42 | So, if we have to crack the throttle stop too far, obviously that's going to increase our throttle position, the Holley does relearn this though on key on so we can cycle the ECU off and on and that will reset our zero position. |
| 03:56 | So, what I'm going to do now, I'll jump out and we're just going to wind that throttle stop in a little bit and see if we can't get the IAC position down closer to about 10%. |
| 04:05 | Alright, a couple of small adjustments there and basically by making adjustments and having a quick look at our IAC position, we've quickly got that dialled in where we want it at 10%. |
| 04:16 | So, everything's looking really good there. |
| 04:19 | What isn't looking quite so good now that our engine is up to temperature is our closed loop control. |
| 04:24 | So, we can see that we are sitting on our 14.0 target but of course our closed loop compensation is showing minus 11% in order to get there. |
| 04:31 | Not that surprising given what we've been dealing with here but we'd like to get that a little bit closer before we move on so what we're going to do is again highlight the entire table, remembering we're still making changes to the whole table here and we can use our control and left arrow, remembering that'll take out 5 % so we'll just press that once and we'll just wait and see how that responds. |
| 04:54 | Straight away we can see that our air fuel ratio does go leaner and our 10% has now dropped to 5% so we're pretty close there, we'll just use the control and left arrow key one more time and hopefully that should get us pretty close to zero and in fact it has. |
| 05:11 | So, now we're cycling back plus or minus about 1% and again it's important to just recognise how fussy we want to be here. |
| 05:19 | The air fuel ratio is always a slightly moving target so when I say I'm targeting 14.0, I'm going to be pretty happy if I'm between maybe 13.9 and 14.1. |
| 05:29 | And for the same reason, we're trying to target a closed loop control of 0%, it's just unrealistic, that's what the closed loop is there for and if I'm saying plus or minus maybe 2% or 3%, I'm going to be pretty happy that my tune's in the ballpark of where I need it to be. |
| 05:48 | At the moment while I've been talking, we've been cycling between I think 1%, zero and minus one so we are right where we need it to be. |
| 05:56 | So, at this stage we've got our engine idling, there's a couple of other things that I would want to check here and if we cycle through our little panels at the bottom here, another thing we want to check is making sure that our battery voltage is stable and charging. |
| 06:10 | It's a little bit low here but old engine, old alternator, we're sitting at a 750 RPM idle, normally I'd expect the battery voltage with the alternator charging to be 13.8 to maybe 14.2 volts. |
| 06:23 | Likely that that's going to come up a little bit as we get a little bit of RPM on board. |
| 06:27 | But if the alternator wasn't charging, we'd much more likely be sitting somewhere in the region of maybe 11.5, maybe 10 volts or something by the amount of time this has been running while I've been talking. |
| 06:39 | So, that's OK, likewise our manifold absolute pressure, this sort of goes hand in hand with what I was saying at the start where we need to make sure that our engine is idling at a reasonable RPM and also just as much as the RPM is important, the manifold pressure. |
| 06:55 | So, this would be pretty typical for the combination we've got. |
| 06:58 | If we can't make the engine idle at a sensible RPM and we find that our manifold pressure's sitting at maybe 75 or 80 kPa, that would be a red flag that something's not right there, maybe we do have a cam timing issue or some other mechanical problem going on. |
| 07:14 | So, at the moment everything here's checking out really nicely. |
| 07:17 | Other things I will mention here which should go without saying, generally I would actually check these during our initial startup. |
| 07:23 | If this is an unknown engine, we want to make sure we've got good oil pressure. |
| 07:27 | Out of sight here we do have an oil pressure gauge and I can see we're sitting at about 30 psi or 20 psi right now at idle so oil pressure's good. |
| 07:36 | The other thing we want to be checking with an unknown origin engine is making sure we don't have any ugly mechanical noises that could be potentially indicating something is catastrophically wrong and we also want to make sure that we don't have a lot of fluids leaking out onto the workshop or dyno bay floor. |
| 07:54 | So, at this point with our laptop tuning software, we've got our idle dialled in nicely, we've got our fueling at idle dialled in nicely and we're ready to move on to start our steady state tuning. |
| 08:05 | However before we do that we will have a quick look at the same process using the touchscreen. |
