Tuning: AEM FIC Fuel Map Steps!

A grateful reader has commented on the closed loop tuning post and asked about putting down my tune to help visualise the map better with numbers.

I really don't want to screen shot my tune as it's super tempting to just plug the numbers in and although it would probably work, it will certainly be different to what you need because my setup will be different!

So as a compromise, how about we go through the steps of setting up a base fuel map! That way you can set it up yourself and adjust it according to your setup as well as being able to visualise how the numbers go in the cells!

Let's have a look!

Creating a Base Map

Before making a map, make sure you setup your AEM FIC and AEM software correctly and apply an appropriate MAF clamp etc!

The quick and dirty way of putting together a base fuel map is through the AEM FIC's automated base fuel map builder. Copy a cal file and rename it as your new tune, then open it. With the new cal file opened, ensure that your X and Y axis are setup (if not, chart the map first!) and now right click anywhere on the map to bring up the context menu. In the menu select 'Create base fuel map'.

It will now bring up the create base fuel map window. In this window all you need to do is fill out the fields. If you've changed your injector size, go ahead and fill out the before and after capacities, if not, just leave these fields the same. Next fill out the expected max RPM of your setup and expected max boost.

So if my setup will have a max RPM of 8,000 and a max boost of 20 PSIA (or 5 PSI boost, at sea level), I'd get the following base fuel map:

  

If you look at the map, it's quite conservative and assumes that you'll begin to max out your fuel input towards the higher end of the load (Y-axis) (e.g 83.6% more fuel). It's better to be overly rich, than over lean, especially in that region!

It also seems that the automated base fuel map accounts for possible over-boost or boost creep conditions (e.g. if your internal wastegate has potential obstructions preventing venting of exhaust gases) evident by the additional values pass the max boost value of 20 PSIA. Nice!

As you can see it already looks like the basic turbo map I depicted in the map charting article.

The main differences is that the AEM FIC automated base fuel map doesn't have a specific 'Transition' area as from 15 PSIA (read on the Y-axis) the values are 0 (i.e. do nothing) and the vacuum area is much larger (which gives you resolution to tune when not in boost).

What I like to do is to begin enriching fuel just prior to boost coming on in the 'Transition' area, more of a safeguard against a lean condition. Also, as we are using a piggy back system, we want to work with the existing factory computer and allow it to do its thing when not in boost, then help it out when boost comes on. Therefore, I don't usually have a large resolution for the 'Vacuum' portion of the map.

The automated AEM FIC base fuel map is quite handy to put together a quick map. Especially if something catastrophically fails and you somehow lose your tune but need to drive your monster back to the lab!

From here you can begin tuning..... But! Before we get into it, how about we look at the manual way of setting up a base map. Here's how I would do it!

First I would identify the maximum boost that the turbo will produce. In this example we have a max boost of 20 PSIA (or 5 PSI at sea level). From the AEM FIC Tuning Tips, a good rule to have around 125% more fuel at 30 PSIA. In our example of 5 PSI boost, this is quite small, so let's be conservative and pump in 50% at the turbo's expected max boost to make the AEM FIC hold the fuel injectors open for 50% longer time.

Tip! Rather than type '50' for each individual cell, you can fill the cells with the same value by fudging the 'calculate' function; here's how:

1. First select the first cell you want to put a value in. 
2. Select the last cell and put that same value in.
3. Highlight those cells.
4. Right click the highlighted portion and in the context menu select 'calculate'.
5. Smile

Next, let's add an emergency buffer for over boost. With 50% at max boost, let's put in, say, 75% at the top of the PSIA scale.

Now we want to fill out the gap between the max boost and max buffer by using the calculate function. Simply highlight all the cells from 25 PSIA through to 20 PSIA, right click and hit calculate. Boom!

The calculate function fills the gaps by linearly adding the gap values. This is super useful so you don't have to calculate the gap values yourself.

Now we can look at the transition and initial boost PSIA break points. Now, boost will begin at around 15 PSIA (sea level). Search around the web for the atmospheric pressure in your locale to determine exactly what value it may be for you! At 15 PSIA, I want to begin enriching the fuel. So before boost, at say 13 PSIA, I'll add 3%, then at the boost, at 16 PSIA, let's put in 10%.

You'll also notice that sometimes if you input a single number, the AEM software would put in a decimal (you can see it in the pic above). This is normal and the small amount isn't material enough to account for.

Now for the gap between the two, we'll do another calculate function as follows:

Then finally, we can do a calculate between the gap between the first boost break point of 16 PSIA to max boost at 20 PSIA.

And that's the manual base fuel map! The values are quite linear but that's fine because it gives us a working point. All this linearity will change once tuning begins and you won't be able to recognise your map after!

You can see that there is a significant difference between the manual method and the automated. The automated takes are more conservative view, while the manual method relies on the knowledge of the tuner to add conservatism.

So for fresh tuners, probably take the automated base map as it's very conservative hence more forgiving. If you know your setup and understand tuning, go ahead and create your base map manually.

Now it's time to tune.

Tuning

There two main aspects you should be looking at when tuning; target air-fuel ratios (AFRs) and power. So optimally you should tune on a dyno, but if not, you can roughly tune AFRs on the road.

First go on a conservative drive and check that motor performance under vacuum is unaffected. Then you can slowly begin going into boost (closed loop/open loop tuning).

Start with low boost in closed loop to ensure that you're going rich (e.g. 12, 11, 10 AFR). If so, then you can stop and go straight to open loop tuning. If not, adjust your map to enrich the low boost areas.

For open loop, do a quick full throttle run and make sure you keep an eye on your AFRs. If they get too lean, stop immediately and add fuel to the lean cells. If they are already rich, then good. You can then begin to tune at the different boost break points from the maximum boost down to the lowest boost pressure while in open loop. At each break point just aim to have a rich AFR (e.g. 12, 11, 10).

Let's take the manual base map as an example. During the full throttle runs I found that I was running too rich on the top end and too lean at the low boost areas. So I'll adjust these values.

A quick way to adjust cells, is by clicking a cell or highlighting a range of cells, then press CTRL-U (to UP the value) or CTRL-D (to push the value DOWN) at small increments. Remember to adjust bit by bit, but you'll get the feel for how much after awhile. Here's the updated map:

Once you have an acceptable open loop tune with rich AFRs, you can now go onto closed loop tuning which will more than likely touch the lower boost levels.

Basically follow the procedure in the closed loop tuning post for closed loop tuning:

1. Setup fuel values in your fuel map.
2. Perform run.
3. Check target values (AFR, power etc)
4. Adjust O2 map to minimise fuel trim fluctuations.
5. Repeat from Step 1 until you reach your target values

Now you won't get your target AFR each and every time, so if you can get a close enough value to your target, then you can stop there; there's more to go.

Okay, so I do some closed loop tuning and I find that I still need to enrich the low boost portions. My updated map would be as follows:

Cool! Now it seems that I've finished tuning open and closed loop! I can now sit back and relax... not really. Although this tune will probably be fine. You'll find that the values will not only differ for the loads on the Y-axis but also RPM range in the X-axis.

This is where power runs come into play. When you jump on a dyno and tune for power, you'll find that at different RPM break points; you'll uncover lean/rich spots and power holes. So you'll then begin adjusting the tune for these. Bump up the cells for lean spots, trim cells with rich spots and have a look at cells that produce a flat power curve. Also note that you may also find that at some rich/lean spots it may actually make more power! It will  then be up to you whether you adjust to hold your target AFR or to keep it.

So after doing power runs I find that I have a rich spot between these RPM values and adjust accordingly:

And then perhaps I want to be more conservative at high RPM values and to prevent pinging, I'll enrich the top end RPM cells:

So after several runs you can see that the map has changed significantly and you may recall the following pics from my previous posts:

The orange are the cells that were adjusted during tuning, with varying amounts of compensation. Quite similar to what we've done:

And as you tune, you'll begin to see the different zones I talked about in closed loop tuning.

So is that it? No...

Once you've got your fuel map to a generally acceptable tune, be prepared to mess it up even further! You will then need to tune the O2 map and possibly the ignition map and MAF map. Any tinkering in these other maps will require you to adjust your fuel map more. Any tinkering with your physical setup (e.g. new exhaust, new injectors etc) will again necessitate tuning.

As you can see it's quite hard work! But the more you do it, you'll get the feel for it and begin to understand your setup and what it needs.

Remember, piggy back tuning (especially O2 map compensation) is not easy. It's pretty dam hard. So persevere!

If you have any questions, suggestions or even like to share how you do your tunes, feel free to leave a comment!

Good luck!!