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Practical Reflash Tuning: Step 2: What Modifications Have Been Performed?

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Step 2: What Modifications Have Been Performed?


00:00 - Our next step is to consider what modifications have been made to the vehicle.
00:05 And I already mentioned in the introduction that the car has been fitted with a Sprintex Supercharger kit.
00:12 And we need to consider how that's going to affect our tuning process.
00:16 What we may need to be addressing in the software when we go to set up our base ROM, and any other considerations that we may need to make before we actually get involved with the tuning.
00:30 So, typically, when we are looking at was is a relatively major upgrade to a naturally aspirated engine that is fitting a Supercharger and adding forced induction.
00:40 One of the biggest considerations we'd normally have is the need to increase the size of the fuel injectors, or for that matter, the fuel system in its entirety.
00:51 So this may be the pump as well as the injectors.
00:55 With the Toyota 86 platform we are actually in a unique position because the engine is fitted with both direct injectors and port injectors.
01:05 Now, in naturally aspirated form, this gives the engine quite a lot of headroom in the fuel system.
01:12 This means that the factory fuel system can actually cope quite happily with forced induction.
01:19 Typically, the factory fuel system is capable of supporting somewhere in the vicinity of about 250 to 300 horsepower.
01:29 So that's a reasonably large increase over the factory rating of 200 horsepower, and this means that we're not going to be needing to rescale our MAP to suit a different set of injectors.
01:41 We are going to be able to run with the factory injector numbers there, and that's going to simplify our job.
01:47 Likewise, we can consider the MAF sensor, the mass airflow sensor, and this is still the stock MAF sensor.
01:55 Again, just through experience we know that the factory MAF sensor is able to comfortably read the air flow that we are likely to see out of this particular Sprintex Supercharger.
02:07 So we are not going to be maxing out the MAF sensor's scaling.
02:12 The MAF sensor is still stock as I mentioned, and it is also still fitted to the factory air box.
02:18 Now, while it is still fitted to the factory air box, the car has been fitted with an uprated TRD air filter, and also the intake tract after the air box has been altered, obviously to suit the Supercharger.
02:33 What this means is that we may be able to expect some changes to our MAF scaling, albeit, they should be relatively minor, and certainly it should be close enough that we will be able to start up and run the engine.
02:49 As far as the exhaust system on the vehicle goes, that is relatively standard, and it's just had a rear TRD muffler fitted.
02:56 So that's not going to have much impact on our tune.
03:00 The engine is still fitted with the stock headers, and the stock catalytic converters are in place.
03:06 Lastly, we also need to consider the manifold absolute pressure sensor, or MAP sensor.
03:13 Now, it would be typical to upgrade the MAP sensor when we are going from a naturally aspirated engine to one fitted with forced induction.
03:23 Normally, we'd want that MAP sensor to be able to read above whatever boost pressure we're expecting the engine to see.
03:32 Now in this case with the Toyota 86, we're in a unique situation.
03:37 We're going to be relying on the MAF sensor solely for our load calculation, and, as I've mentioned, the factory MAF sensor is able to adequately read the mass air flow we're expecting with the Supercharger.
03:52 So, the MAP sensor, the factory MAP sensor will read to about 1.36 bar absolute pressure or 0.36 bar of positive boost.
04:03 Our Sprintex Supercharger should be producing somewhere around the vicinity of 0.5 to 0.6 bar.
04:10 So, it's going to be exceeding the reading ability of that MAP sensor.
04:16 However, we don't actually need that MAP sensor for any of our tuning inputs.
04:22 Also, we don't necessarily need to incorporate a boost cut or overboost protection on this style of Supercharger because our boost pressure is fixed relative to engine RPM.
04:36 So, we know we're not going to have something like a wastegate failure, which we may see in a turbo charged engine and see our boost run away uncontrollably.
04:44 So, while on the face of it, it might sound a little unusual, in this particular installation, it's quite common practise to keep the factory manifold absolute pressure sensor, and rely solely on the MAF sensor for our load input.
05:01 Okay, so lastly, because we are increasing the air flow dramatically over what the naturally aspirated engine was likely to see, one of the considerations we are going to need to make when we are addressing our tune and setting up our base ROM file before we start tuning, is we are going to be needing to look at any load limits imposed in that factory ROM file, and remove those so that the ECU can adequately read more air flow or more load than the engine was likely to see naturally aspirated.
05:35 So that really covers the base aspects that we are going to need to be looking at when we configure our base ROM file.
05:43 We've now got a solid understanding of what modifications have been made to the engine, and more importantly, how those modifications need to be treated in configuring our ROM file.
05:54 Let's move on with the next step and we'll look at what we need to do.

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