Practical Standalone Tuning: Step 4: Base Ignition Timing
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Step 4: Base Ignition Timing
13.19
| 00:00 | - The next step of our process is to set our base ignition timing and base fuel pressure, ready to start the car. |
| 00:07 | Now this particular step, we're actually going to have to do in two steps or two takes because initially we haven't got the engine running so we're going to have to broadly set these parameters, get them close, as close as we can in the ballpark so that we can start the car. |
| 00:22 | But then once we've actually got to a point where we've got the engine started for the first time and it's comfortably idling by itself, we're going to come back and readdress both of these parameters and get them dialled in much more precisely. |
| 00:35 | Now let's deal with each individually and discuss why that's the case. |
| 00:41 | First of all, let's talk about our fuel pressure. |
| 00:43 | We've got an electrical fuel pump here that is driven by battery voltage. |
| 00:48 | The more battery voltage that's provided, the more fuel flow the pump can provide and while yes the regulator to a degree should account for this, we can see a small variation in our fuel pressure between the normal 11.5 - 12.5V we'll see right now with the engine not running and the 13.8 - 14.2V, we'll see when the engine is running and the alternator is charging. |
| 01:12 | So this means that if we set our fuel pressure now with the engine not running, once we've got it up and running we may expect to see a small fluctuation. |
| 01:21 | Now the other element that comes along with this is what fuel pressure should we be running and there is no black and white answer to that. |
| 01:29 | Most return style or manifold pressure referenced fuel pressure regulators will run around about three bar or 43.5 psi and that's exactly what we're going to be shooting for here. |
| 01:41 | That deals with our fuel pressure, we'll look at setting it in a second. |
| 01:45 | Moving on, let's deal with our ignition timing. |
| 01:48 | Now at the moment we can only crank the engine and when we're cranking the engine, we've already seen we're getting around about a 200 RPM cranking speed. |
| 01:56 | Remembering that we've got 12 teeth on that distributor that the ECU is seeing as its trigger input, these are turning at half engine speed as well because it is driven off the camshaft so we're actually seeing six teeth go past that pickup per engine revolution. |
| 02:14 | So this is not a very high resolution input and due to the variation in cranking speed due to compression etc, we will tend to see if we're watching the timing with a timing light, we will tend to see a bit of a variation in the ignition timing, might move around by a couple of degrees back and forth. |
| 02:32 | That's absolutely no problem and we'll get into the ballpark enough that we can start the car but we want to be much more accurate when we're actually tuning the engine. |
| 02:41 | So we'll get it into the ballpark at cranking speed and then once the engine's actually up and running and we've got it idling and we're happy with all of the idle elements, we can come back and reassess this and make some slightly more fine tuned adjustments at a higher idle speed, maybe 1500 to 2000 RPM. |
| 03:00 | At that point because of the frequency of those teeth going past the pickup, the ECU's getting a lot more data, it's lot more consistent and we should see a relatively rock solid ignition timing with our timing light. |
| 03:14 | And on that note, what we are trying to do here, just to reiterate is align the timing using a timing light in the engine bay that the engine is actually seeing wiht what we're seeing on our laptop and this is really important to make sure that those are in alignment so we don't end up doing some damage to our engine due to over advancing the ignition. |
| 03:33 | Alright let's start now by having a look at our fuel pressure. |
| 03:37 | We do have an adjustable fuel pressure regulator in this instance so we can set this to essentially almost whatever we want. |
| 03:45 | What we want to do is run the fuel pump sp we can see what that pressure is and we've already had a glimpse of this earlier in the worked example. |
| 03:52 | Coming into our PDM outputs here, we can see our output number one is our fuel pump and we've got this nice little button here we can press to test that output and that'll run the pump for a few seconds, enough time to essentially get a sense of what that fuel pressure is. |
| 04:08 | Now to monitor this, we've got our fuel pressure gauge or fuel pressure sensor I should say, that we've already set up, we already know about this. |
| 04:15 | That's currently showing 134 kPa so we've got a little bit of residual pressure in the system. |
| 04:20 | Let's turn that test on and we'll watch and see what our fuel pressure jumps up to. |
| 04:26 | It's sitting at 297, 298 kPa so we're within a couple of kPa of our target, 300 and as I've already said, chances are that when the engine's up and running and our battery voltage is at 14V, we're likely to see that bump up so I'm not too worried about that now, I won't make further adjustments. |
| 04:45 | If we do want to make adjustments, it's simply a case here of loosening off the locking nut, it's a 13 mm or half inch locking nut and then we can use a 10 mm spanner to actually adjust the regulator in or out to raise or lower the pressure. |
| 05:01 | In the next step where we actually adjust that pressure with the engine running, it is really important to understand that if we're using a manifold pressure reference, we want to actually remove that while we're setting our fuel pressure. |
| 05:15 | This of course is just as simple as removing the vacuum hose off the fuel pressure regulator and blanking that. |
| 05:22 | And the reason we need to do this is of course at idle the manifold is pulling a vacuum or the engine is pulling a vacuum in the inlet manifold and the job of that fuel pressure regulator is to raise or lower the fuel pressure relative to that manifold vacuum so essentially if we were pulling 50 kPa of vacuum and we wanted a 300 kPa base fuel pressure, with that vacuum hose connected, we'd actually only be seeing 250 kPa of fuel pressure in our MTune software so really important to understand that, always want to set our fuel pressure with the engine running so we've got full battery voltage and the vacuum hose disconnected. |
| 06:01 | Now that we've dealt with the fuel pressure, let's move on and we'll talk about our ignition timing. |
| 06:07 | As I've already mentioned, we're trying here to align the ignition timing so that it matches what we're actually seeing in the laptop and to do this we're going to need a timing light. |
| 06:16 | Don't need anything flash here, for our example here we are using a Snap On dial back style timing light. |
| 06:23 | I actually recommend that you get started using a very simply inductive timing light with no dial back function. |
| 06:30 | If you don't understand the dial back functionality which allows you to delay the timing event, then you can actually get yourself into trouble, particularly on waste spark engines. |
| 06:40 | So an inductive timing light simply will flash the timing light every time a spark event occurs. |
| 06:46 | That needs to be connected to number one cylinder and there's a couple of options around this. |
| 06:52 | If you're running a conventional Honda B series engine with ignition leads then it's as simple as connecting the inductive clamp around the number one cylinder ignition lead. |
| 07:03 | In our instance with individual coils, this is a little more complex. |
| 07:08 | In some instances the timing light will be sensitive enough to actually trigger off the low voltage side or the wiring to the coil. |
| 07:18 | if that's not the case though what we can do is temporarily remove the ignition coil, run a short lead from the coil to the spark plug in the cylinder head and then we can of course put our inductive clamp around that. |
| 07:30 | The other element we do need to understand here is what we're actually looking at in terms of the timing marks on the engine. |
| 07:38 | Now on the Honda B series engine there is a plastic mark on the front cover that we use as our alignment, this is a long protrusion on that front cover, it's relatively simple to see and that points at the crank pulley. |
| 07:53 | On the crank pulley itself we've actually got four marks, we've got a white mark that's removed from the other three. |
| 08:01 | That is actually TDC on number one cylinder. |
| 08:04 | Then we've got a set of three marks, we've got a red mark which represents 16° and then we've got a mark either side of that which is plus and minus 2°. |
| 08:13 | So generally if we're not using a dial back timing light, we're going to be wanting to use that red 16° mark, the engine should idle quite nicely when we get to our next point of setting our timing at 16° so that's the one we want to actually be using. |
| 08:28 | Another subtle element here which we haven't mentioned yet is the Honda B series engines, unlike the majority of engines in existence are actually a reverse rotation engine. |
| 08:38 | Almost every other engine in existance will rotate clockwise if we're looking at the crank pulley, the B series actually rotates anti clockwise. |
| 08:47 | Now that's important to understand because this references when we're advancing or retarding the timing which way we're expecting to see that pulley move. |
| 08:56 | Right now let's have a look in our software and see what our controls actually are for functioning this when we're setting our timing. |
| 09:03 | In order to complete this step, let's shrink down our PDM menu and we'll come to our inputs and we're going to come across to our trigger and home inputs, we've already looked at this in one of our previous steps but if we scroll down to the bottom, we've got everything we need here to set our base timing so the first of these is our trigger angle so this is essentially the offset the ECU will use to adjust the timing. |
| 09:29 | We already know we've got that set at 431°. |
| 09:32 | And we can advance and retard this and that will have the effect of moving the actual timing the engine is receiving. |
| 09:39 | Before we do that though, we want to lock the timing at a value we can see and in order to do that we've got our trigger angle options. |
| 09:46 | We don't want the engine to try starting at this point so we can click our little tick boxes to disable our fuel and our ignition and then we want to lock our ignition angle as we've already discussed, this means the ECU will ignore all the table values and just output a fixed value and we can see that that is already defined as 16° which we've just discussed matches our red mark. |
| 10:09 | From here it's a case of using a helper so that we can function the starter motor and someone else can actually check and look using the timing light at the crank pulley and from here it's just basically a case of cranking the engine and then adjusting our first tooth angle here, 431°, advancing that or retarding that until we've got the timing sitting as close as we can to that red mark. |
| 10:34 | Again it doesn't have to be absolutely perfect at this point, as long as we're within about 3-4° of that timing mark, that will be enough to get us up and running and then we'll be able to move on with the following step of our 10 step process, getting the engine actually started and idling for the first time. |
| 10:53 | Now again to reiterate, it's really important once we've gone past that step to come back and readdress this base timing as well as our fuel pressure. |
| 11:03 | Now when we are checking the base timing after the engine has started for the first time, there's a couple of aspects that we want to consider. |
| 11:11 | The first of these is checking the timing at an elevated RPM as I've mentioned so that we've got a nice consistent input of our trigger inputs to the ECU so that we're getting a very stable timing mark or timing light is very stable and we can see exactly what the timing's doing, it's not moving around. |
| 11:30 | Might move around half a degree or so but it should be really nice and stable so then we can set our first tooth angle really accurately. |
| 11:37 | The other element of this though is particularly with the variable reluctance sensors, as we looked at in the trigger mode module, if we have the polarity of our sensors inverted, we can still get the engine to run but what we're going to end up doing is seeing quite a significant amount of timing drift as the RPM increases. |
| 11:54 | So what we want to do to check this, we want to leave our timing lock set, so it's still outputting 16°. |
| 12:01 | We've set our timing at maybe 1500 to 2000 RPM, now we want to rev the engine up to maybe 4000 or 5000 RPM and just make sure that we don't see a significant drift in our timing. |
| 12:12 | It's totally acceptable if we see the timing move around maybe a degree or maybe 2° as we raise the RPM, but if we see a significant swing, that is a red flag that our polarity of one or both of our reluctor inputs may be incorrect. |
| 12:28 | The other element we can do here once we get to a point where the engine is up and running, if we want to fine tune the timing drift relative to RPM, and I'm not talking here about with our polarity incorrect, this is assuming we have got the correct polarity and we're seeing that small drift of a couple of degrees from idle up to maybe 6000, 7000 RPM. |
| 12:47 | Come back into our software here, we come up to our ignition and ignition settings, you'll remember that we talked about our ignition system delay and this can be used to fine tune the delay and hence make sure that we've got stable timing at idle all the way through to our rev limit. |
| 13:06 | So with this step completed, we've now got our timing dialled in, we should be in a positon where we can actually get the engine started for the first time in our next step. |
