Vishnu Performance Systems

Tuning Map Files with XMap

Basic XMAP Features

Version 1.0 Beta (Early Release)

General Overview

This instruction set will get you up to speed on the very basic features of XMap. Please read it thoroughly. While these instructions cover only ignition timing and fuel table tuning, this is more than enough for most tuning purposes. Advanced XEDE tuning features such as boost control, knock sensor sensitivity, map file switching, RPM/Load breakpoint location, fuel/spark enrichments, adjustment range changes, input and load variable changes, etc,. should only be attempted by an experience user/tuner. Besides, we’re not done with the documentation yet.

And finally, while the EVO is a fantastic car with a very stout motor, it is already quite highly stressed in stock configuration. Common sense and good judgment must be used when determining how much is too much and when and where to stop before something nasty happens.

Tuning: Getting Started

Step 1
Connect to XEDE

Make sure ignition power is “ON” and ensure a good serial cable connection between the XEDE and the serial port in your laptop.

Step 1

Launch XMap

If you do not have it, it can be downloaded, at an additional cost, from our website at Once downloaded and installed into your computer, it will prompt you for registration information. Once completed, it will fire off an email to our software developer, Rhys, who will then reply with an unlock code (once authorized) which will complete the installation of XMap on your computer. Make sure you install XMap on the computer you wish to tune on as each software instance is linked to one particular hard-drive. In other words, don’t install it on you home desktop computer if you plan on using your laptop to tune with.

Once XMap is launched, you will see the following window:

Step 2

Go to the file menu and select and open the desired map file you wish to start with.

Step 3

Now, some tables and graphs should appear on the screen..

Table/Graph/Screen Descriptions

The Monitor Screen

This window provides a real-time display of engine speed (RPM), MAF in signal, MAF out signal, Timing Advance offset, etc,. It also displays an ongoing log in the screen on the right. In the case of the EVO, disregard MAP in and MAP out as we do not use MAP voltage for anything useful. Future software revisions will eliminate this useless info and replace it with something far more interesting.

Fuel Table and Fuel Graph

The Fuel Table controls fuel delivery. On the bottom X-axis, we have Engine Speed (RPM). On the left Y-axis, we have Engine Load. With the EVO, engine load is represented by MAF. So, in essence, this table dictates the revised MAF signal output based upon the original MAF signal (Y-axis) and Engine RPM (X-axis). It may sound a bit wacky but we assure you that it actually works. Those familiar with speed density-based stand-alone engine control systems may be more used to relying on MAP (Manifold Absolute Pressure) for Load determination. That also works but would require the addition of an external 3-Bar MAP sensor. Nonetheless, MAF works better on the EVO, so get used to it. The Fuel Graphs is simply a graphical 3D representation of the Fuel Table. This graph is helpful in spotting any typos or unwanted numbers in the Fuel Table. In almost all situations, the Fuel Graph should look relatively smooth with no big jagged spikes or dips that would indicate a bad entry. Not nearly as sensitive to change as the Spark Advance Table, one can make incremental offsets as large as 0.5-1.0 fuel units.

This is an example of a bad entry:

The mistake is hard to spot the table but clear as day on the graph. See how useful that graph can be in catching mistakes!!

Spark Advance Table and Spark Advance Graph

This table controls spark advance (also known as Ignition Timing). The 3D graph is of UTMOST importance here. Look at it EVERYTIME you make a change. If you see a big spike or dip, you probably put in a wrong number. Here’s an example of a mistake that can blow up your engine:

See that +6 degree offset in the table? No? Look harder. It occurs at an engine load of 65 and engine speed of 5700. That little mistake will send your piston flying through your block! Please note that it is very important to make small incremental changes to timing when tuning your car. NOTE: The EVO responds very obviously to ignition timing changes as small as +/- 0.2-0.4 degrees. In fact, most of the curve smoothening we do when tuning a car on the dyno is by making these small changes. Those who insist on making incremental changes as big as +/- 2 or 3 degrees are going to be very disappointed (if not infuriated) with the results.

Helpful Tuning Hints

Know where you are on the Graph

This means you should what that spastic yellow cursor that is bouncing around on the tables. This cursor indicates what region of the table the engine is currently operating it. Nothing is more infuriating that putting the right changes into the wrong cell. One little trick that is helpful is to select the entire table with your mouse/touchpad. As the yellow cursor moves around the table, it will highlight the cells it passed through. This is especially helpful when dyno tuning as you can see what load was achieved at any given engine speed. To reset the table, simply lick on the window border of a background table.

Look out for Knock

One nice feature of the XEDE is that it doesn’t interfere (unless we want it to) with the factory knock control system. This means that all the advance noise filtering and knock control logic programmed by those clever engineers at Mitsubishi is still intact and perfectly function. One clear sign that you’re running too much ignition advance or too lean in certain cells is spurious knock retard (induced by knock control activity}. This can be seen by a sudden loss of torque while operating under heavy engine load (high boost). This is easily seen on a dyno. This activity can also be picked up by an OBD-II data logger/scan tool which is display a sudden reduction in nominal ignition advance. For instance, during a full-throttle 4th gear pull from 3000 to 7000 RPM, ignition advance (as displayed on the OBD-II tool) should log something like this:

5, 5, 6, 6, 7, 8, 9, 9, 10, 10, 11, 12, 14, 15, 16, 17, 19, 20

Notice how ignition advance is increasing with engine speed? This is good and normal. The following is not:

5, 5, 6, 6, 7, 8, 7, 6, 5, 7, 8, 9, 9, 10, 12, 14, 15, 12, 14

This last log would indicate substantial knock sensor activity. In other words, the factory knock control system is yanking back ignition timing to guard against sustained detonation (which it has detected). The car will feel lumpy and slow. It needs less timing and/or more fuel.

Get your hands onsome Cans!

Detonation cans, that is. This is nothing more than a set of amplified headsets connected to a microphone which cam be clamped on to the engine. With it, you can listen to your engine purr. Actually, it won’t sound all that good since all you will be hearing is piston slap, valve clatter and misc. mechanical hoo-ha. But you will knock as clear as a bell! This is a must for any serious tuner. I can’t tell you how many times I’ve found the human ear (with a little electronic help, of course) to out-perform a knock sensor when it comes to distinguishing engine noise from actual knock. I never tune without it.

Don’t Make Changes at Low Loads

It is a very good idea to keep the bottom 3 or 4 load rows free of timing changes. There is no reason to add or subtract timing during anything other than moderate to high boost conditions. Doing so can interfere with the factory diagnostic and knock control logic. Likewise, there is little reason to modify the fuel tables during off boost conditions. Unless, of course, you are running larger injectors or intake systems (which we do not recommend, by the way) that often result in MAF sensor misreading

Less fuel usually requires less spark advance

Everyone and their mothers know that a stock EVO runs very rich. This over-fueling is for knock suppression. When dialing back fuel through the Fuel Table, one usually has to pull back ignition timing as well in the same RPM/Load pointsof the Spark Advance Table. Failure to do so, especially when running on 91 octane California gas, may result in knock sensor activity and overall torque loss.

Make ONLY one change at a time

Tuning is very difficult when you are making more than one change a time. When doing so, it is virtually impossible to properly quantify the effects of each individual change as they often interact with each other in a way that would leave even the most experienced of tuners puzzled. That said, a good tuner first does several dyno pulls to establish a good stable starting point. Then, make one small change (say a -1.0 in all cells of the fuel table above a Load of 30. Then do several more dyno pulls to properly quantify the results of that change. See where the enleanment helped and where it hurt. It is important to do several runs in order to allow the factory ECU “adjust” to the new operating conditions. Once you are satisfied with the results (or at least know the good and bad of that tuning change, you can move on to the next change and repeat the whole process. It is not unusual to make 20 or 30 passes on a dyno in order to achieve what can be considered optimal tune.

Always leave a little on the table

While it’s tempting to run the most aggressive, highest horsepower producing dyno-tested tuning map on the road, it’s important to realize that the real world introduces conditions not often found in a dyno facility. For one, the air is almost always “truer” whereas the air in a dyno facility is almost always contaminated with some degree of inert exhaust gas. This means that most cars will run noticeably leaner on the road that they did on the dyno. Add to the fact that real world conditions will often subject a car to prolonged periods of heat-soak, sustained periods of load and other adverse conditions, and you have a recipe for detonation. This is why it is always a good idea to slightly detune your final tuning file before you hit the streets. Usually, this requires nothing more than an extra 0.2-0.3 degree of ignition retard and a 0.4-0.7 point extra fuel. This little extra headroom goes a long way in maintaining a proper safety margin.

Aim for smooth results

So often in the world of aftermarket tuning, we come across cars that make dick-swinging peak horsepower and torque numbers yet the curves look jagged and full of dips and valleys. By any decent standard, this represents a poor-running car, regardless of what ¼ mile ETs or anyone else may suggest. An engine is nothing but a pump. And like all pumps, an engine possesses a unique volumetric efficiency curve. Like most things in nature, this curve is always relatively smooth. And, not surprisingly, it looks just like a torque curve. The goal of tuning is to take advantage of this natural efficiency curve in order to maximum area underneath it. Not only does this lead to a quicker car, it also feels a lot more pleasant. With full control over fuel and spark delivery, take it upon yourself to fill in these performance gaps. They don’t belong there. You’ll be amazed with a tiny 0.2 degree bump in timing advance does to an ugly dip in a torque curve. Just make sure you put it in the right place or you could potentially create another rough spot! Too big of a bump and you will lose a lot of torque due to knock-induced ignition retard. If timing manipulations don’t work, try fuel changes. And then a combination of the two.

Don’t get overzealous with boost pressures

Don’t ever forget that the EVO already runs A LOT of boost from the factory. The reason it doesn’t make as much power as it can isn’t because it’s not running enough boost. It’s because it’s not making efficient use of the boost it is running. This is the problem that needs to be solved. Do NOT add more boost until you’ve exhausted your efforts tuning the Fuel and Spark Advance tables. It is not unusual to make 15-24% horsepower gains without even touching boost pressures. This is the sign of a good, efficient and safe tune. While raising boost can yield good power gains, it does so at the expense of thermal efficiency. This means that less of the combustion energy is used to push the piston downwards during the power stroke and more is wasted in the form of heat which travels out the exhaust and into the cylinder head and cooling system. Nine times out of ten, the engine which makes the most power with the least amount of boost is the most consistent, least thermally stressed and most responsive of the lot. This is especially true in octane limited situations where knock is most prone to occur.

Interpolation works. Use it.

On some dynos, it is impossible to conduct proper partial throttle testing. This means than anything less than full throttle yields untested results. This being the case, it’s often a good idea to interpolate the fuel and timing offsets from low to high load along the Y-axis. This effectively smoothens out your Fuel and Spark Advance Tables which almost always results in a smoother-running engine. For example, let’s say I just tuned a car on a Dynojet and the following Fuel Map changes were made:

Notice that only the cells that were used during a full throttle run were tuned. All the cells on the lower end of the load spectrum are unchanged;. Needless to say, that results in a pretty rough looking Fuel Graph as seen below:

We already know that we should keep “0” the lowest few load rows since they represent the cruising and very light load conditions that we don’t need to tune. So it looks like we need to “blend” the higher load offsets downwards so that they smoothly become “0” by the lowest few load rows. Fortunately, we have a nifty interpolation feature. All we need to do is select the area we want to smoothen with the mouse:

And then click on “Edit” in the Real-time Engine Monitor window. Go to “Selection”. Then go to “Interpolate”. The following screen with then pop up:


Click on “y axis” and hit “OK”. Lo and Behold:

Repeat this process working towards the left of the screen and you will eventually end up with this:

With the 3D graph looking like this:

WARNING

As with all engine tuning systems, the user always accepts risk when tuning or trying different map files. It is up to the user to make sure he/she tunes carefully and/or uses the appropriate map file. This means that all tuning efforts must be matched carefully to the given set of upgrades and available octane fuel. Failure to do so may result in poor engine performance or even severe engine damage. Please use your best judgment when using the XEDE. Like any powerful tool, it can be misused as well as it can be used. Use it for good, not for evil.