Practical Standalone Tuning: Step 4: Base Ignition Timing/Fuel Pressure
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Step 4: Base Ignition Timing/Fuel Pressure
08.21
| 00:00 | - We're now at a point where we're just about ready to start our engine for the first time. |
| 00:04 | And what we need to do as part of this is to set our base fuel pressure and our base ignition timing, both of these aspects will have a major impact on the way the engine operates and hence they will affect our tuning. |
| 00:17 | In terms of setting our base fuel pressure, in the case of our Mazda MX5 there is no adjustable fuel pressure regulator fitted to the engine so we have no ability to adjust our base fuel pressure and it will be at the manufacturer's base setting of 45 psi or three bar. |
| 00:35 | That being said, even with a stock fuel system where we have no ability to adjust the fuel pressure regulator, it's still a worthwhile exercise to at least check and measure that fuel pressure and make sure that we do know it's where it's supposed to be. |
| 00:49 | Particularly with an older car, maybe the fuel pump isn't quite up to the task anymore and we may see a situation where the fuel pressure has dropped dramatically below where it should be. |
| 00:59 | It's also worthwhile keeping this fuel pressure gauge fitted to the engine for the purposes of our tuning because particularly at high load and high RPM, this is where a fuel pump that's a little bit past its use by, just struggling a little bit, really will make itself known and this can really save a lot of time or a lot of wasted time where we're trying to tune around an issue where the fuel pump simply can't keep up with the engine's fuel requirements. |
| 01:25 | So in our case we don't need to consider the fuel pressure, we know that it is at 45 psi, three bar, we can move on and discuss our base ignition timing. |
| 01:34 | And this is really critical and one of the areas that I see a lot of, even experienced tuners overlook. |
| 01:41 | Particularly when we are dealing with a plug and play ECU such as our MS3 Pro here, it's very easy with a base map to just assume that the base ignition timing is set correctly. |
| 01:51 | Now just to reiterate from the body of our course, when we are talking about that term base ignition timing, what we're really talking about there is aligning the ignition timing values that we're seeing digitally on our laptop screen and making sure that that actually represents what the engine is receiving. |
| 02:09 | And in order to do this we need to fit a timing light to number one ignition coil and we need to actually be able to see the timing marks on the front crank pulley. |
| 02:18 | What we're going to do is do this in two ways. |
| 02:21 | At this point in our process we haven't really got to a situation where we can start the engine for the first time and it's always a good idea to just approximately set the base ignition timing to start with. |
| 02:33 | Now we can do this just by cranking the engine with the ignition system and the fuel injectors disabled so that the engine can't start and we're not going to risk having the engine flood itself with fuel. |
| 02:46 | This requires a helper, what we're going to do is attach our timing light to number one cylinder, number one ignition lead, we're going to physically be watching the timing and then we're going to have our helper crank the engine. |
| 02:56 | And what we're going to do there is adjust the timing until we're at least approximately in the ballpark. |
| 03:02 | At this point, we only need to be pretty coarse, around about three to five degrees from our timing mark will be close enough. |
| 03:09 | Because we're not going to be able to accurately set our base timing just during cranking. |
| 03:14 | Once we've got the engine up and running in our following steps, we can come back and revisit the ignition timing, the base ignition timing and set this more accurately and what we want to do is make sure we've got it set at idle, making sure that it is absolutely on our marks. |
| 03:29 | Even when we are doing this, often at a low idle speed of maybe 700 or 800 RPM, we may find that the timing tends to wander around a little bit so it's a good idea during the process of setting our base ignition timing to actually bring the engine RPM up using the throttle a little bit to perhaps 1500 to 2000 RPM and set it there. |
| 03:51 | Let's jump into the software and we'll see what all of this looks like. |
| 03:54 | So we're going to go to our ignition settings menu here, we'll open that up and the first option we're going to look at here is our ignition options/wheel decoder. |
| 04:03 | Now the setting that we're going to be adjusting here is our trigger angle/offset. |
| 04:08 | We can see at the moment that's set to negative 3.3 degrees. |
| 04:11 | Before we make any adjustments we do need to set the ECU up to supply a fixed advance. |
| 04:18 | So at the moment we can see under fixed angle we've got this set up as we previously discussed to use our ignition table. |
| 04:25 | For the purposes of setting our base ignition timing we want to set this to fixed timing. |
| 04:30 | When we select this option we now have the ability to adjust the timing for our fixed advance in terms of degrees. |
| 04:38 | What we want to do here is adjust this to a number which we can easily see on our crank pulley. |
| 04:45 | This will depend on the particular engine and the marks available on that crank pulley. |
| 04:48 | 10 degrees on our Mazda B6 engine is easy enough to see and when we've got the engine running at a later point and we're coming back to fine tune this the engine should idle relatively well or run relatively well with a timing advance of 10 degrees. |
| 05:02 | For the first part of our process though, because we will be setting the base ignition timing during cranking we also need to consider here our cranking advance degrees. |
| 05:14 | So what this means is that when the ECU is deeming that the engine is under cranking conditions, it will be supplying a fixed advance of 13 degrees. |
| 05:22 | It's important to understand that distinction because otherwise you're going to be trying to target the incorrect timing. |
| 05:29 | So for simplicity during our base ignition timing process I'm just going to set both of those values to 10 degrees. |
| 05:36 | Alright what we can do is close that down now and if we come back to our ignition settings menu, this time we're going to come down to our trigger wizard. |
| 05:43 | This is a nice graphic way of setting our base ignition timing. |
| 05:48 | What we're going to find is that when the engine is cranking or running, the advance value here will show the advance the ECU is supplying at the time so we know exactly what the advance is that the ECU is expecting, we can check that with our timing light and then if there is any discrepancy we can simply adjust the ignition angle offset here to correct it. |
| 06:09 | So this is the process we're going to go through when we're setting our base timing. |
| 06:12 | Making those adjustments as we've just seen inside of the ECU, setting our base time initially coarsely during cranking and then once we've got the engine up and running, coming back and revisiting this and fine tuning it. |
| 06:24 | Once we've got to a point where we can fine tune the base ignition timing with the engine up and running, we also want to check for timing drift. |
| 06:32 | Now there's two reasons we're checking for timing drift, the first of these is to ensure that we've got our reluctor polarity around the right way if we are using a reluctor sensor. |
| 06:42 | Or alternatively our input capture is on the correct edge. |
| 06:46 | If that's not correct, as we increase our engine RPM with our fixed timing being output, we're going to see our timing drift quite substantially so if we see that we know that we've got something wrong there. |
| 06:58 | Let's just close down our trigger wizard here, we'll go back to our ignition settings and our ignition options/wheel decoder. |
| 07:06 | So you'll recall that our ignition input capture is this particular parameter here, currently set to rising edge which we know is correct for the Mazda MX5 cam angle sensor. |
| 07:20 | Now the other aspect here which is a little bit less severe is setting our spark hardware latency. |
| 07:28 | So at the moment you'll note that that's set to 50 microseconds. |
| 07:31 | So what we're doing here is accounting for the latency in the hardware for the ignition system. |
| 07:38 | And basically we're going to be adjusting this so that the ignition timing we're seeing at the crank pulley is the same at 1000-1500 RPM as it is at 6000-6500 RPM. |
| 07:49 | If we're not seeing the exact same timing there, we can adjust our latency to correct that. |
| 07:55 | So once we've got our timing set coarsely and we've got it fine tuned and we've adjusted for any timing drift, it's really important to also remember to set the timing back to use our table. |
| 08:06 | So of course we can do that with this parameter again, we're going to change from fixed timing to use table and we can burn those changes into our ECU. |
| 08:15 | With our timing set up, we can move on to the next step of our process. |
