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24,330 Posts
Discussion Starter #1 (Edited)
Don\'t know where to begin? Feeling overwhelmed? Start HERE!

The idea of tuning your own Focus can be intimidating, I know. However, once you learn how to use the SCT Pro Racer package, you'll realize it's one of the best investments you'll ever make in regards to your Focus. This should be your starting point. This is what you'll need to do to get started with tuning your Focus. I feel there is a certain order things should be done, so I will try to cover different aspects of tuning in a particular order. The FIRST thing we need to do is be able to data log.

The following info is presented based on the assumption that you already have your Raptor or LiveLink data logger software and hardware all set up and ready to go.

Here are a few important notes in reference to data logging your Focus:

The first thing you'll want to do is set up your data logging configuration. In other words, pick the items you want to log. Here is what I recommend to start with:


You'll need the key ON or the car ON in order for you to create your logging configuration, by the way. Once you've created your list, I recommend that you Save Configuration. That way you don't have to start over every time you want to data log. You just Open Configuration.
Also, when you are selecting what to log, you may notice that 2 separate Long Term fuel trims will appear in the list. One of them will almost always show .5 as the value. Delete that trim from your list, you don't need it. You'll want to log the Long Term fuel trim that shows 1.000 or something close to it.

It's also good to log the UPPER CASE items if you have the choice. For example if you have "LONG TERM FUEL TRIM" and "long term fuel trim", choose the item that is in UPPER CASE letters. UPPER CASE are Direct Memory Reads ( DMR ) and are updated more often than the lower case items. Lower case items are a standard OBD-II PID.

If you decide to log SPARK SOURCE, here is a reference guide:

0 - crank
1 - base
2 - borderline
3 - torque control
4 - pre-ignition (knock sensor)
6 - stabilized idle low load
7 - cold low load
8 - idle feedback at minimum clip
9 - idle feedback, unclipped
10 - self-test
15 - osc
16 - foreground borderline (tip-in control)
18 - closed throttle decel

Here is a guide for TORQUE SOURCE:

1 - no torque control
2- transmission
2 - traction control
3 - speed limit
4 - rpm limit
5 - tip-in shock control
6 - tip-out decel control
7 - shift modulation
8 - oil temp control
9 - cooling control
11 - turbo charger
12 - PATS
13 - OSC Control

When you are at wide open throttle ( WOT ) you should be in OPEN loop operation. Your version of Raptor or LiveLink "may" not have the proper open loop flag. Some older versions didn't work properly. Select all open loop items ( UPPER and lower case ) in the list to see if any of them work. Delete any that don't, you only need one. If you have none that work, let me know or you can just rely on the short term fuel trims switching to the value in your base fuel table ( see next paragraph ).

Short term trims at WOT display the fuel that you are commanding in the base fuel table or cold fuel table if certain timers/ect temps are not met. In other words, whatever you have requested in the "base fuel" table ( in the top 2 rows ) in the SCT Advantage software is what you should see being logged in the Raptor or LiveLink as the Short Term fuel trims at WOT. This also is a good way to tell when you are in OPEN LOOP in case the flag(s) aren't working for you.

For example -

ST trim = .86
The pcm thinks the mixture is too lean. ADD 14% fuel.
To fix this you would add this by increasing the MAF curve in that area.

ST trim = 1.14
The pcm thinks the mixture is too rich. Remove 14% fuel.
To fix this you would remove this by LOWERING the MAF curve in that area.

LT trim = 1.14
The pcm thinks the mixture is too lean. ADD 14% fuel.
To fix this you would add this by increasing the MAF curve in that area.

LT trim = .86
The pcm thinks the mixture is too rich. Remove 14% fuel.
To fix this you would remove this by LOWERING the MAF curve in that area.

Notice Short Term and Long Terms trims are the opposite in the way they indicate lean or rich conditions. It's important to remember that, otherwise you'll waste a ton of time trying to dial in your car and end up with the opposite of what you're expecting.

Alright, now that we've got everything ready to log, let's start your Focus and start logging at idle. Look at the values. Does it make any sense? Don't worry if you don't know what everything means yet, you'll catch on soon enough. :)

The first thing we're going to do is let the car warm up. We want it to be in closed loop operation. At idle for a short time it will be in open loop operation. You can tell it's in open loop if the fuel trims are NOT changing. Also if your open/closed loop flag is working properly, that will be a clear indicator - 0 means closed loop and 1 means open loop, but sometimes open loop shows a higher number.

Once it's in closed loop we'll then wait for the coolant to reach at least 170 degrees. Now the car is warmed up, let's take a look at the fuel trims.

NOTE: While tuning, it's easier to dial in the MAF if you turn adaptation OFF. To do this, go to SCALARS > adaptive learning > adaptive control switch and change it from 1 to 0.This will keep the LONG TERM FUEL TRIM at a value of 1 and only the SHORT TERM FUEL TRIM will be changing. Trust me, it's easier this way. Turn it back on once you're finished tuning.

The goal with the MAF transfer function is to re-calibrate your ECU so that the MAF is as accurate as possible. You're not actually doing anything to the MAF itself, but merely adjusting the settings for the MAF in the ECU to get the desired air/fuel ratio. This function MUST be dialed in for your car to run at it's best.

In your SCT Advantage Pro Racer software, go to MAF > MAF_transfer_function. The left column shows the Zetec Focus uses MAF counts while the SVT Focus uses volts. Both can be used to tune accurately, so no worries if you have one or the other. In some cases as you are logging you can log both counts and volts. And in some newer versions of the Pro Racer you have added columns allowing you to have counts AND volts. The right side column ( sometimes middle column ) will show your flow - #/MASS, which is what you will be modifying if it's needed. In most cases you will NOT need to adjust the counts or volts column, but I have had the need on occasion. That however will be covered later. :)

So how do we make adjustments to the MAF transfer function? It's pretty straight forward. The first thing to do is figure out how lean or rich you are at a certain point in the MAF transfer function. To determine this, you'll need to data log.

Let's imagine the SHORT TERM FUEL TRIM at idle is reading 0.92 on average. You want to get as close to 1.00 as possible so this means that you're 8% lean at idle. Look at the MAF counts or MAF voltage value at idle. For examle, the Zetec at idle will show around 120 counts, unless you've changed your idle setting. For the sake of learning, let's just take that one cell in the #/MIN column at 120 counts, which is 0.2373 for an LFQ1 Zetec and muliply it by 1.08. To do this, click on the cell once and then right click to select SELECTION OPERATIONS. Enter in 1.08 and then click on the multiply box and then hit OK. The new value in the modified cell will be 0.2559. This should get you VERY close to a value of 1.00 at the SHORT TERM FUEL TRIM at idle now. It may not be perfect, but it's always going to be changing just a bit. You just want to get it as close to 1.00 as possible. The rule is, get within 10% of rich or lean, but I try to do a little better than that if I can.

One REALLY important thing to remember when modifying the MAF transfer function is to keep it sequential. This means, the cell you just modified cannot be greater than the cell above it. And it cannot be less than the cell below it. You MUST be sure of this! I've goofed up once before, not paying close enough attention when I first was learning. I was on the dyno. It was interesting. Don't do it. :D

24,330 Posts
Discussion Starter #2 (Edited)
Re: Don\'t know where to begin? Feeling overwhelmed? Start HERE!

Alright, so now we understand how to make adjustments to the MAF transfer function. Now, it's time to get your Focus dialed in as far as closed loop operation is concerned. Here is how I like to approach the next step of tuning your Focus:

Data log @ idle for 20 seconds. Stop. Save file as idle.csv.

Data log @ 1200 RPMs for 20 seconds. Stop. Save file as 1200.csv.

Data log @ 1500 RPMs for 20 seconds. Stop. Save file as 1500.csv.

Data log @ 2000 RPMs for 20 seconds. Stop. Save file as 2000.csv.

Data log @ 2500 RPMs for 20 seconds. Stop. Save file as 2500.csv.

Data log @ 3000 RPMs for 20 seconds. Stop. Save file as 3000.csv.

Data log @ 3500 RPMs for 20 seconds. Stop. Save file as 3500.csv.

As noted earlier, be sure your Focus is warmed up and in closed loop BEFORE you start to log ( unless you are troubleshooting some problem that occurs only at start-up ). And try to hold it as steady as possible. It may take a little practice, but you'll get it soon enough.

I suggest keeping the logs in one folder, call it something like "My data logs." :lol:

Now you have a choice on how to proceed. You can view the logs as a spread sheet ( xcel or quattro ) or you can view the logs graphically with The Raptor or LiveLink. To do this open your data logger and go to FILE > OPEN > idle.csv. I use both methods, but lately I've been using more and more of the graphic format since you can analyze a good amount of data without scrolling forever. Keep in mind that the Raptor and LiveLink log REALLY fast - 60 to 62 times per second kinda fast. Looking at that in a spead sheet can get tiring and sometimes you can miss something if you aren't careful since there is some much info to take in. Anyway it's up to you. :)

24,330 Posts
Discussion Starter #3 (Edited)
Re: Don\'t know where to begin? Feeling overwhelmed? Start HERE!

Now that you are looking at your data logs, you'll want to keep an eye out for trends that may be occuring. Look out for really lean or rich conditions. Of course the SHORT TERM FUEL TRIMS are going to be switching, but you should start to see a pattern. Let's imagine we're looking at your idle.csv log and you're seeing a constant reading of about .85 on your SHORT TERM FUEL TRIM. Look at the MAF counts or volts that are appearing at idle - should be less than 200 counts unless your idle is really high. Now go to the cells in the #/MASS column at the given counts or volts and make your adjustment(s). Since we already know that .85 SHORT TERM FUEL TRIM is lean, we'll want to add some fuel. We'll want to add 15% to be exact, however we'll multiply the given cells by 1.15 to get the results we're after. If you were rich at idle, say 1.14 SHORT TERM FUEL TRIM, you'd multiply the cells by .86 to bring it as close to 1.00 as possible. OK? :)

Pay close attention when you are making adjustments to the MAF transfer function - you can really screw up your car if you are careless here.

Keep in mind, if you are 25% lean or 25% rich, the numbers will stop changing and shortly after you will be thrown into open loop operation. This will result in really poor gas mileage since your oxygen sensor(s) won't be in control any longer. The o2 sensor's job is to get you as close to 14.64 air/fuel as possible for the best fuel consumption at idle and light throttle cruising.

Now that your idle's air/fuel is dialed in, let's move on to the 1200.csv and repeat the above steps.

24,330 Posts
Discussion Starter #4 (Edited)
Re: Don\'t know where to begin? Feeling overwhelmed? Start HERE!

Once you are finished with the 1200.csv, move on to the others and finish them up following the same procedure.

With the SCT Pro Racer you can also see the changes in the MAF transfer function. The MAF curve should pop up in Advantage every time you click on MAF transfer function. In Mako ( Advantage III ) you can click on CHART at any time to view the curve. I don't recommend clicking and dragging points on the MAF curve to make changes - too much room for error in my opinion. Looking at the MAF curve, you'll want to try to have a smooth curve, however, this is not always possible. If you make some hefty adjustments, say like 20% thru a range of cells, you might want to ease into and out of the cells by using a 10% or 15% adjustment so the transition isn't so harsh. Use your judgement, a really choppy looking MAF curve will often times feel choppy, too. Smooth it out if you can. :)

24,330 Posts
Discussion Starter #5 (Edited)
Re: Don\'t know where to begin? Feeling overwhelmed? Start HERE!

At this point, let's assume you've verified that your closed loop MAF transfer function adjustments are all on the money now. That means it's time to go for a drive. An easy drive. If you are tuning your car for forced induction, I'd say stay out of boost at this time - don't floor it! And don't beat the hell outta the car yet. :D

Is the car running well? Does anything feel weird? Hiccups or stuttering? No? Good! :lol:

Now that you're finished with the closed loop operation portion of the MAF transfer function, let's consider open loop operation. The first thing you want to do is decide how you are going to dial in your WOT / open loop section of the MAF transfer function. For most people, this is where the dyno shop comes in. Just about every dyno shop out there will have an air/fuel meter of some kind to monitor and assist in dialing in your WOT air/fuel. If the shop you find does not, you may want to keep looking. ;)

Or you can invest in a quality wideband air/fuel meter, such as the FJO or LM-1. I hear the AEM unit is pretty good for the money, too. Well maybe you don't even have a dyno near you at all. Perhaps you're considering just using a wideband? It would work, ya know. But...

The problem with soley relying on a wideband and not making a trip to the dyno, is that you must tune your car on the street. Unless you have access to some private roads or a race track, you're going to be breaking the law as far as the speed limit is concerned in all but VERY select places in North America. However, that is up to you to decide. I'm not recommending you tune on the street, but if you do, try to have a buddy help you with the laptop so you don't put yourself or other's at needless risk doing it while you drive. :) You drive and your friend works the laptop. OK? :)

24,330 Posts
Discussion Starter #6 (Edited)
Re: Don\'t know where to begin? Feeling overwhelmed? Start HERE!

Now that it's time to address open loop operation and WOT driving, we need to look at a few things:

To set your WOT throttle position, go to Functions > Misc > TP_for_WOT. Change the entire right column to the new desired values. Next, go to Functions > open/closed loop > fuel_open_loop_tp. Change the entire right column to the new desired values. I would start with 500 or 550 counts for Superchargers and Naturally Aspirated applications and for Turbocharged applications I would start with 300 or 350 counts in the entire right column for both tables.

Let's move on...

Base fuel
Go to Functions > Fuel > base_fuel_table
You'll see a table with a throttle position count axis and an RPM axis. The cells in this table are in lambda ( .82 for example ) and is not in air/fuel ratio ( 12:1 for example ).

This table is only going to be in use at WOT, by the way. It has no effect when you are in closed loop. I typically don't modify the 280 and lesser TP counts, but that is entirely up to you and where you have WOT set at.

A value of 1 represents 1 multiplied by 14.64 for an air/fuel ratio of 14.64. A value of .82 means .82 multiplied by 14.64 for a commanded air/fuel ratio of 12:1.

If you have a base file from me you'll see that the top 2 or 3 rows have been modified. Depending on your mod list, the base fuel in the modified top rows can vary. For blowers I like to start with .85 in the early RPMs and then transition according to boost to .82 to redline. This means that I'm starting with 12.5:1 and then rolling into 12.1 to redline if you do the math described above. However, keep in mind this does not mean that you are going to want to leave this table as I have it. For naturally aspirated cars, I usually like to start off much leaner and transition into .88 to redline. You may want to start with .82 across the entire top 2 rows, which would be better for guys with turbos.

Remember, the base fuel table and the MAF transfer function should be correctly modified to work together. Simply put, you want to set the base fuel table for what you want as your actual WOT air/fuel ratio. Then you do the math in the MAF transfer function and modify it to deliver what you are asking for in the base fuel table. Some people go in and make adjustments to the base fuel table instead of the MAF transfer function. I do NOT recommend this. I feel that the base fuel table should only be set to indicate the desired air/fuel and not for adjustment.
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