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Practical Standalone Tuning: Step 4: Base Ignition Timing/Fuel Pressure

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Step 4: Base Ignition Timing/Fuel Pressure

07.08

00:00 - Our next task before we're ready to actually start the engine is to get our base fuel pressure set and our base ignition timing set.
00:10 Now these are two really critical aspects of tuning and they're often overlooked so we'll talk about them now.
00:16 First of all we need to set our base fuel pressure and what we can do here is going to depend on the car we're tuning.
00:23 In the case of our Nissan 350Z we can't actually adjust the fuel pressure it's a stock fuel system.
00:30 So we can't adjust that fuel pressure but it is important to know what that fuel pressure is.
00:36 You'll already remember that during our base configuration we set the static or base fuel pressure, so the ECU needs to actually know what that fuel pressure is.
00:47 So it's important to measure the fuel pressure this can also highlight problems, if there is something wrong with your fuel system and the fuel pressure is far below what it actually should be.
00:59 So in this case we can't actually adjust the fuel pressure but we do need to know what it was and it was sitting around about 380 kPa so we've entered that into the ECU already.
01:13 Setting the base ignition timing, what this does is it calibrates the numbers that are showing in the ignition timing tables with the ignition timing that is actually being delivered to the engine.
01:28 Now this is really critical because when we've got an ignition timing number digitally displayed on a laptop screen it's very easy to blindly believe it.
01:38 However, if it isn't calibrated correctly, if the base ignition timing isn't set correctly, then it's quite possible that the engine could be receiving either more or less ignition advance than we have in our ECU.
01:55 So the process of doing this requires us to physically connect a timing light to the number one coil on the engine, and we need to watch the ignition timing on the crank pulley while the engine's running.
02:10 Now obviously at this point we actually haven't got our engine running but if that's the case what we can do is set the ignition timing roughly with the engine cranking.
02:23 Now you'll remember we've already looked at this what we can do is disable our injectors if we go to our main set up, click on the fuel tab and click disable injectors and we want to apply that change.
02:37 What we're also going to do at the same time is we're going to click on our ignition tab and we're going to go down to lock mode and we're going to set to always on.
02:48 So what this does is it locks the ignition timing, regardless of the numbers in the actual ignition tables.
02:55 So in this case the timing that the ignition will be locked to can be adjusted by setting it in this firing angle box.
03:04 What we're trying to do here is set the ignition firing angle at a value that's easy for us to see on the crank pulley.
03:13 If the engine is running we want to hopefully be able to set this to an ignition advance that the engine is going to happily idle at while we're setting our base ignition timing.
03:24 So once we've done that and we've applied those changes, what we can do is we can go back to our trigger menu and our TDC offset angle is where we adjust our base ignition timing.
03:38 So what we can do now is crank the engine.
03:40 We're going to need a helper to watch the timing on the crank pulley.
03:44 And we can coarsely adjust our TDC offset angle until the ignition advance is approximately whatever we set as our firing angle.
03:55 Now this, as I said, is a coarse adjustment we're not going to be very accurate, or be able to be very accurate, if we're setting this just cranking the engine.
04:04 This is going to be enough just simply to get the engine up and running a little bit later on.
04:09 And if this is the case what we would do is once we've got the engine idling correctly, we would come back and revisit this step and be a little bit more accurate about it.
04:19 It is very important that this is done accurately, what you'll find is at cranking speed the trigger inputs are not coming into the ECU fast enough always to enable it to provide really stable and rock solid timing.
04:37 It's quite common to see the ignition timing or the timing light move around a few degrees when the engine is being cranked.
04:44 So as I say we can use this to coarsely adjust the ignition advance, get it close enough for the engine to actually start up and then we need to come back and revisit this.
04:56 Now for the same reason when we are actually adjusting the base timing with the engine running it's often worthwhile to set the base timing with the idle speed slightly raised so if we have an engine that's normally idling at 750 or 800 RPM it can be worthwhile bringing the RPM up to maybe 1500 to 2000 RPM.
05:19 And that should give a much more stable ignition angle that we can see with our timing light.
05:26 At the same time once we have set the ignition timing at idle or low RPM it's also worth revving the engine up, taking the engine RPM up to perhaps 4000 or 5000 RPM and just watching the timing to make sure that it doesn't drift.
05:44 Particularly if you're using a magnetic or reluctor input for your trigger inputs, it's very easy to have the polarity of those sensors incorrect and in that case what's going to happen is the timing will drift quite dramatically as the engine RPM increases.
06:01 I'll point out that it isn't uncommon to see the timing move perhaps one or two degrees between idle and the red line of the engine, the rev limit of the engine, that's typical.
06:13 If we're getting this sort of timing drift we would be seeing timing drift of 20 or 30 degrees so it's very dramatic and very obvious.
06:22 So remember this is a two step process, we're going to make a coarse adjustment here.
06:26 Once the engine is actually running happily, we're going to come back, revisit it and be more accurate with our setting.
06:33 It's really important to make sure that once you've set the base timing, we come back to our ignition tab here and disable the lock mode.