Updated September 2022 by Jerry Hoffmann

Chapter 3 – Garbage In, Garbage Out:  A properly installed, configured, and tuned Engine Management System makes all the difference (The Three Stages of Success)

GIGO Garbage In Garbage Out

GIGO:  Garbage In, Garbage Out.  It’s a pretty simple principal.  Whatever you put into this type of project will absolutely play a role in the final product you have when you are finished.  It’s a very simple principal.  We aim to help you know how to do this, and to have the confidence to dive in, and to know you’re doing it right.  You’ll also learn when it might make sense to ask a question, whether it be on a public forum, or to our tech support team, or maybe to a local (or even remote) pro that can assist you.  Maybe you’re confident in the tuning, and the configuration, but when it comes time to turn up the boost on the dyno you may want to hire someone to help rather than to tackle that yourself, particularly if your motor is significantly modified to make a lot more power than stock and you want to make sure it’s done safely the first try.  (It’s awesome to get the chance to learn this on a stock-ish motor and add that skill to your toolkit, but it’s optional, either way—we’ll help you understand it well enough to know how to find good help and not overpay! 


Three ways to screw it up – One way to be sure you get it right, every time.   

Let’s say you have a perfectly installed and configured Engine Management System on your engine.  But you, or a tuner, don’t tune the system properly to meet the needs of your engine at all operating conditions.  You, or they, put some ‘garbage in’.  Your results will not be what they could be if you tuned it properly.  That’s pretty obvious of course—we all know it needs to be tuned right. 

But did you know that in order to tune it right, and for that tune to be able to do it’s job—it absolutely HAS to be installed right?  Well… of course you do!  That wiring needs to be reliable using quality wires, connectors, and crimps – and the sensors need to be in the right locations on the engine, and adjusted properly in some cases (crankshaft and camshaft position sensors for instance need the proper gap to the trigger wheel), and the ignition/plug wires can’t be draped across the highly sensitive signal wires, or the ECU itself, introducing electrical noise into the system.  Even things such as choosing the right spark plugs can make a difference, and we’ll make sure you’re up to speed on everything you need to consider there.   

So we’ve talked tuning, we’ve talked installation.  What’s left?  Configuration.  You can’t just throw the system at your race car or street rod, wire it up perfectly and install everything just right….  and expect it to control things you haven’t told it how to control, can you?  No of course not.  Now don’t let that scare you—we’re going to go through it all.  And much of it is pretty common sense/self explanatory.  Fuel Injector Size.  Coolant and Intake Air Temperature sensor type.  Throttle Position Sensor operating range (where is 0%?  where is 100%?  It’s as easy and holding it there and clicking a button to tell the ECU this is 0, and this is 100… boom!  Done).  Configure the Ignition system type and a little information (or in many cases, choose from a drop down list in TunerStudio) on the crank wheel and cam wheel.  Basically just, well, the basics — you tell the ECU what you’re controlling, in many cases choosing from a list of options, though we can support just about any engine out there, so we give you the ability to configure even the weird stuff too!  (see below)

This stuff is pretty basic.  The MS3Pro and our other MegaSquirt and MicroSquirt Engine Management Systems are INCREDIBLY versatile.  These EFI Systems can be used to tune a single cylinder engine, a multiple cylinder engine (odd-fire engine or even-fire engine).  They can be used to control and tune a Japanese or Korean Engine, a European Engine, or a US Domestic Engine (or pretty much any other).  So understanding that—know that with that level of flexibility and configurable versatility—we’ve gotta know what this sucker is installed on!  Cause we can control darn near ANYTHING!  We’ve even had customers controlling radial airplane engines, in a CAR!!!

Radial Airplane Engine in an Toyota MR2 controlled by MegaSquirt EFI


Bottom Line—Configuration is a key stage of Engine Management System Success.  It’s not that hard generally, but it must be done.  We’ll show you how.  Let’s say you’re bringing your car to a professional dyno tuner, and you want that process to go smoothly (and to cost no more than it needs to!) – we’ll help you to be ready.  And your tuner will thank you.  They can send us a note and thank us too if they want 😉



What do I do with this thing?  How do I reach Engine Management System Bliss?!? 

So you did your research, you placed your order for that shiny new MS3Pro ECU or maybe one of our other Engine Management Systems (or any system really, this applies to all, but… why would you go and do a thing like that? WE LOVE YOU!  Please LOVE US BACK!  😉 ). 

And now it’s sitting in front of you, fresh out of the box.  You’ve got your ECU and your wiring harness and other bits you may need.  The car is in the garage.  You’re looking at it anticipating that first start and the inevitable vroom vroom sounds it will soon make to put a huge smile on your face.  What do you do now?  Well…  I’m going to recommend you already got a start on this, but by all means…    RTFM!!!   (That means Read The Full Manual, no matter what anyone else says it may mean! 😉 )

Read the Manual.  We put a ton of hours into making it complete.  I will be covering all of the general, and many specific principles, of installing and tuning your ECU, but you’re going to need the information that’s in that manual that’s specific to the exact Engine Management System you are installing

You can find the manual for any of our products whether it be MS3Pro, MSPNP, MicroSquirt, or on the DIYAutoTune.com website PRODUCT PAGE for the product you’re installing.  Look for the DOCUMENTATION Tab.  Click it, and start reading.  Don’t worry about it if it doesn’t all make sense if you’re new to this.  Some portion of it will.  Keep reading this guide.  Keep reading the manual.  Read them again.  It’s going to click.  It’s going to make sense.  We’ve helped literally tens of thousands of people do this since we started back in 2005.  We know how to help you succeed and we’re with you along the way.  Reach out to us at [email protected] if you need any help finding the docs you need, and if you have questions along the way!  The manual and this EFI Tuning Guide will go a LONG way to helping you answer those yourself – and this is a living document, we’ll be adding to it over time.  Check back!



The Cheat Sheet Life Hack Easy Button of EFI – MSPNP Plug-And-Play Engine Management Systems

Before we dive in deeper, let me share with you a little Easy Button option that many of you will have.  We do the wiring.  You just plug it in.  We do the configuration for all base features used on a stock-ish vehicle, you only need to configure for anything you’ve changed (injector size for instance) or any features you want to add to your vehicle.  Adding a flex fuel sensor – configure the ECU to know it’s there (just turn it on and tell it what kind of sensor)! 

Even the tuning process we help you cut out a HUGE portion of the process on.   

Our MSPNP Gen2 and MSPNP Pro (MS3Pro PNP) systems do an amazing job of taking care of these parts of the process for you.  If you have a factory EFI engine and we have a solution for your vehicle, or even for your engine that you’ve swapped that came out of a different vehicle originally and that we have a PNP ECU solution for—I highly recommend considering that.  No wiring, or just the tiniest bit in a couple cases.  Minimal configuration related to any differences from our engine to yours.  And far less tuning effort.

You save time, and in many cases, you save money.  It’s a tradeoff- you come away perhaps with less of an education, as we eliminate most of the learning curve for you by doing it for you.  The rest of this guide will still be incredibly valuable to you I am confident, you will learn a lot that will help you make the best decisions, and know all that is involved to get the results you desire.  But you’ll save time, and possibly mistakes.  It’s up to you to decide which path you’d like to take.   



Here’s what it comes down to:  The Three Stages of Success

The three stages of success - Installation, Configuration, and Tuning

  • The Installation Stage 
  • The Configuration Stage
  • The Tuning Stage 

These are each SEPARATE and DISTINCT phases on your path to Electronic Fuel Injection and Ignition Control Ecstasy!  Skip or pay little attention to any of these, and you’ll have more trouble than you have to.  But YOU DON’T HAVE TO HAVE TROUBLE.  We aim to help you avoid most or all of that.  Read on…. 


The Installation Stage—Installing an Electronic Fuel Injection (EFI) and Ignition Control System 

    • Wiring 
      • Vampire Taps and Wire Nuts need not apply!
      • It’s CRITICAL that you wire your ECU properly, using the right tools, techniques, and with consideration of wire routing (keep your high voltage ignition system separate!) and grounding schemes.
      • Use quality automotive grade wires, sensors, relays, fusing, etc.
      • Properly crimp all connections
    • Sensor Selection
      • Reuse or sharing of factory sensors
      • Installing new / aftermarket sensors
      • Adapting factory/OE sensors from another vehicle
    • Where to mount the ECU and related components
      • Firewall?  Custom removeable mount plate?  Glovebox?
    • Do Spark Plugs Matter?  Yes they do!   
      • Always use a resistor plug.  No, you won’t lose spark energy.  Even though you can make the system work properly with a non-resistor plug….. use a resistor plug!

That’s just a very light overview…. check out the Chapter 9: Engine Management System Installation for more! (coming soon)



The Configuration Stage – Configuring an Electronic Fuel Injection (EFI) and Ignition Control System 

    • Coolant Temperature Sensor (CLT) Calibration 
    • Intake Air Temperature Sensor (IAT/MAT) Calibration 
    • Manifold Air Pressure (MAP) Sensor Calibration 
    • Throttle Position Sensor (TPS) Calibration 
    • Camshaft Position Sensor and CamShaft Position Sensor types
      • VR Sensor (works great!  Sometimes takes a little adjustment) 
      • Hall Sensor (my favorite, easy, common and rock solid!) 
      • Optical Sensor (works as well as using a Hall Sensor, but less common overall) 
    • Crank and Cam Trigger Type and Trigger Pattern – (that may sound a little scary, don’t let it!)  Tell your ECU exactly that…. are there 4 teeth on the trigger wheel each time it turns?  Are there any missing teeth?  I know, I know, maybe you’re not sure what a missing tooth is yet.  We’ll get there soon, keep on!
    • Engine Idle Air Control Valve (IAC) – Configure your ECU in TunerStudio to use the type of IAC valve you’re using, make sure it’s functioning by commanding it to close all the way, and open all the way, and just make sure the engine responds.  It should idle down when closed, and up when open as it’s letting more air into the intake. That’s all you need for now.
    • Other and optional items – Perhaps you have other things you need to configure for features that are optional, like Flex Fuel/E85 blending, or Boost Control, or Knock Sensing.  Keep in mind though that many of these, as they are not REQUIRED to run the engine in most cases, can wait a bit.  If you’d like, you can do this in different steps, and go back to the three stages of success when it’s time to add that new feature.  Installation, Configuration, and Tuning.  You can go through this process for the initial REQUIRED featureset to run your engine, and then revisit this process to add those other features if you’d like.  You’ll understand things far better then, and you’ll be less likely to overwhelm yourself now.   


Continuing The Configuration Stage:  First Start, Base Timing, and Base Table Configuration

  • First Start – getting it to fire up and idle!  YEEESSSSS!!!!!! 
  • Setting the Base Timing in TunerStudio – This is what ‘synchronizes’ the ECU and your Timing Light so they agree.  That has to happen so that the ignition timing that the ECU is commanding is the ACTUAL ignition timing you can see with a timing light.  Then they’re in sync. And the timing you COMMAND, will be the timing you GET.  
  • AFR Target Table – Scaling and Setting AFR Targets – Scale your AFR Target Table for the operating range the engine will be used in.  On the Y Axis of the table (that’s the vertical axis) you’ll put your minimum MAP sensor kPa (or a few kPa less) reading in, and at the top you’ll enter your maximum expected MAP sensor reading.  Maybe that’s 100kPa for a naturally aspirated engine.  Or 200kPa for a turbo vehicle making 14 or 15psi.  Then scale the other range in between.  Similarly, on the X Axis (horizontal), you’ll enter the RPM range you plan to operate the engine in.  From Idle RPM up to Redline RPM, and scale the numbers in between.   Even scaling is probably good for this exercise, or close to even.   THEN, you need to configure the values in this table to the appropriate Target AFR values you want to run.  We’ll provide you with more guidance on this, but in the end, it will look something like this:  [Image Needed – Well tuned Target AFR Table, with transparent overlay identifying the different areas of the table (idle/cruise/high power/overrun/etc), like we did in the earlier chapter for the fuel/ignition tables.] 
  • Tuning the VE/Fuel Table to Idle reasonably well Select all the cells around idle—and adjust them up or down to idle right about 13:1-13.5:1 is a good starting point.  A little rich, but happy.  A good trick is to adjust the fueling to where the engine makes the MAXIMUM amount of vaccuum—meaning the MAP sensor value (in TunerStudio) is as low as possible.  That’ll get you in the ballpark even if you don’t have a wideband o2 sensor.  (to be revisited in the Tuning Stage)
  • Scaling Fuel/VE Table and Spark/Ignition table columns and rows – You know what RPM you want to turn that engine out to, and you know if you’re going to be running naturally aspirated without a turbo or supercharger, or if you’re going to be turning up the BOOST.  You simply change the values in the tables to match the operating range that the engine will be used in.  If you’re running up to 8000rpm and you plan to run a turbo or supercharger at 14psi of boost, you set the tables up for this range.  Or maybe that naturally aspirate Small Block Chevy (SBC) will be turning to 5500rpm and there’s no need to dedicate part of these tables to somewhere that the engine won’t operate—scale the table There are some considerations as to whether you evenly space these, or if you keep some ranges closer together where maybe things happen fast, and spaced further out where change happens slower, and we’ll get into all of that.  It’s not scary, and it can be fine tuned later during the tuning process if needed.  You just need a place to start. 
  • Spark Timing/Ignition Table rough in – knowing what you know about your engine, you setup the ignition table to represent this as close as possible.  It’s an educated guess.  You can search and find Ignition Advance Tables that others have used online, but word of caution—check your source.  Don’t just grab a table someone else says is good and send it!  Do you own sanity check.  What if they had their base timing off?  The whole table would be off!  So, sanity check!  How?  Well, just the same way that the guy/gal that’s guesstimating their ignition advance table WITHOUT trying to use somebody else’s Spark Table to start with.  The ‘old fashioned’ way.  For some engines, this is pretty easy as the numbers are well known going back for 60 years.  For others,  it may take a bit of research.  For that 350 Small Block Chevy (SBC) or most other variations of that platform, with factory heads or at least factory or similar compression, you already know that that needs.  Look at your distributor’s advance curve.   You know it probably gets about 10*BTDC (Before Top Dead Center) at idle.  About 36*BTDC at full throttle where it’s making the power.  Maybe 20-something degrees in the cruise range.  And perhaps 44 degree or so in the overrun range when you’re off the throttle decelerating but still in gear (there’s some gas mileage to be found here!).    I recommend erring on the side of ‘slightly retarded ignition advance, maybe 10% or so—so if it should need 36 degrees BTDC all in at mid-high rpms and ful throttle, maybe run it at 32deg BTDC for now.  Apply similar scaling through all operating ranges, except idle, where you can go ahead and keep it pretty much where you know you’ll need it.  We’ll get into both of the above methods soon enough, in the Configuration chapter. 

    Typical Small or Big Block Chevy Engine Ignition Advance Curve using a Mechanical Distributor
    See the prior chapter for more info on how use this simple centrifugal advance distributor advance curve to create the foundation for your ignition table with MS3Pro/MegaSquirt Electronic Ignition Control!
  • Fuel/VE Table rough in – kindof the same thing as the item above.  There are VE Table Generator tools that will help with this.  If you can input some basic parameters about your engine like Engine Displacement, desired idle RPM, how much vaccuum there is at idle (you can look at this now that you’ve got it idling), maximum RPM, the expected peak horsepower and torque (a guess is ok), and how much boost you’re running, if any—then there are tools we’ll share with you that make this easy.  Alternately—you can pretty much look at your idle VE numbers, and how they compare with the rest of the fuel table, and adjust them to be inline. Regardless of the method used, I recommend erring slightly to the rich side, as it’s better to start there and lean it out as you tune than to start to lean and rich engine damage.  More on that below.  Then as you tune, you’ll be close enough to not be WAY off more than likely, and the tuning process will go smoothly.    


 And NOW it’s the moment we’ve all been waiting for:  Now YOU’RE READY TO TUNE YOUR ENGINE!!!


I got a little carried away and that ended up being more than just an overview….  but there is a lot more to share.  Check out the Chapter 10: Engine Management System Configuration for more! (coming soon)



The Tuning Stage – Tuning an Electronic Fuel Injection (EFI) and Ignition Control System 

Ahhh…. the fun part where you get to see it all come together and you get to see the results.  Man, that first start is amazing.  Getting it to idle well is great.  What’s next? 

 I’m going to break this up into a couple sections based on this.  Some of you may want to do PART of this, and I’ll help you know which parts you can do to save you money and time if you’re taking it to a professional dyno tuner for the main tune.  And some of you will want to do all of this yourself and learn something POWERFUL in the process.  All of you will learn a ton in this process regardless of which route you take.  It comes down to time and money largely.  We’ll help you save as much of both as we can.   

The Tuning Stage – The First Steps

  • Cranking Pulsewidths & Engine Start Up Tuning – This involves more than just ‘getting it to start’.  This is making your engine start easily, every time, at any temperature.  You will find the engine needs more fuel to crank, the colder the conditions are.  This can be a bit tedious, but doesn’t all have to be done now, you can revisit it after the main portion of the tune so long as you’re happy enough and it starts well now.  Over time though, maybe just once a day during the colder parts of the year, you get this dialed in so that no matter the temperature, it fires right up.  The next items play a role in this as well, it all works together. 
  • AfterStart Enrichments (ASE) and Warmup Enrichments (WUE)– When your engine first starts, the ECU applies what’s known as AfterStart Enrichments (ASE) for the first few seconds.  This runs the engine with extra fuel for the first few seconds of operation, due to the fact that until there is a little heat in the engine, the fuel doesn’t atomize and ultimately vaporize as well as it does with a warmed up engine.  ASE/AfterStart Enrichments last only a few seconds and start high, then taper down to where they no longer impact engine fueling.  It’s important to understand that this works in conjunction with the WarmUp Enrichments, which lasts until the engine is fully up to operating temperature.  If you’re target “I’m ready to roll” operating temperature is say 160*F, or 180*F, then you use WarmUp Enrichments (WUE) to add fuel during the warmup process, for the same reason as ASE, due to reduced efficiency in atomization and vaporization of the fuel, but ALSO just to get the engine warmed up quickly and into it’s most efficient (and healthy) mode of operation.  Not too hot, not too cold… we want that porridge to be just right there Goldilocks! 
  • Engine Idle Air Control Valve (IAC) Initial Tuning –  The goal here is to open the valve MORE when the engine is cold and needs to warmup, and to close it as the engine comes up to operating temperature.  This will work in conjunction with AfterStart Enrichment to some degree.  It will moreso impact WarmUp Enrichment, so you may find yourself revisiting those some as you run the IAC Valve through it’s range.  Additionally, with the valve open—you’re likely idling with less vacuum, and because of that in a slightly higher cell in your fuel table.  You may need to adjust the fueling and possibly even ignition timing in those cells.  In the end, the goal is for when you start the engine, for it to idle higher than normal when cold particularly, and to warmup the engine.  Then as it warms up, the idle speed comes down to whatever you can idle the engine at for best manners.  You can always revisit this later as well, but it’s good to go ahead and play with it a little bit at this stage and maybe get it in the ballpark.   
  • Fuel Tuning while free revving the engine gently – From here, you can begin to dial in your VE Table/Fuel Table as you gently apply throttle in neutral and let the engine rev slightly.  Don’t go banging on it!  Just ease into the throttle, watch your wideband o2 sensor’s gauge on the dash or in TunerStudio, and if it’s lean in that cell—give it more fuel.  If it’s rich, pull a little fuel out.  You may need to multi select a few cells at first and rough it in, then you can fine tune per-cell in the VE Table.  You’re not looking to get up to high RPM or load.  Just a thousand or maybe two RPM, and 20% maybe higher in the load range.  You’re just giving the motor some manners and getting it ready for full a full tuning session. 
  • Acceleration Enrichments – If you’ve run a carburetor, you’re familiar with the concept of the Accelerator Pump.  This is a circuit in the carb that adds a small squirt of extra fuel when you hit the throttle at a faster rate than the ‘gentle’ throttle you just gave it above.  With an Electornic Fuel Injection System you have full control of HOW MUCH extra fuel is added when the throttle is applied at different speeds.  Slower throttle will need a certain amount of extra fuel, faster stabs of the throttle will require a different amount of fuel.  There will be more to tune here later—but for now, you just want to give it some manners in that low rpm/load range, which is generally the bottom left of the Fuel and Ignition Tables on our Engine Management Systems in TunerStudio.  This is how you give that engine the ultra-crisp throttle response that only a well tuned Electronic Fuel Injection system can give you at no matter what rate you punch that loud pedal.   



The Tuning Stage – The Dividing Line – Your Engine is ready to finish the tune.  Who’s doing that and what’s involved?   


If it’s you, here’s the overview of the process, and we’ll be going deeper in a later chapter.  If it’s your local, or remote, dyno tuner—they’ll take it from here.  Either way—you’ll find value in knowing the process.  So… what’s next in that process to tune your engine? 

At this point, you should have a reasonably well manner car that will start, warmup, idle, and accelerate in neutral.  You’ve resisted the urge to rev it to the moon, or to take a drive yet.  That Is wisdom.  Let’s get on with this tune so you can let all that caged up horsepower and torque out and unleash it upon the unsuspecting world that awaits. 

 Fuel Table / VE Table Tuning – At this point, whether you’re doing the tuning or hiring a pro – ideally you’ll be taking the car to the dyno.  Your ignition table should be fairly conservative at this point.  Maybe with 10% or so less ignition advance than you think you may end up needing when the tune is complete.  Your fuel table should be, if anything, estimated slightly on the rich side.  You DO NOT want to run your engine pig rich at 10:1 for instance on gasoline for any amount of time as it will wash away the cylinder lubrication the piston’s oil ring will have distributed, and in extreme cases you can wash down the walls and thin out your oil, with fuel, and that’s not a good thing.  So you’re at the dyno — In that controlled (and safe!) environment, you or your tuner can operate the engine under various load and rpm conditions, simulating the load and RPM that the engine will be used at, and they, or you, can tune each cell in pretty short order and develop out a full fuel/ve table. 

Alternately there are ways to do this at the track, or other closed course.  Don’t drive around with a laptop in your lap on public roads even if your vehicle is road legal.  That’s dangerous and dumb.  You could perhaps, on a road legal vehicle, or track / closed course, have someone ELSE drive your car for you while you sit in the passenger seat with the laptop.  Still not advised on public roads, particularly if the car is not yet tuned well enough to get around with decent manners, but it can be a usable tactic. 

Throughout this process, your AFR Target table you setup earlier can serve as a guide.  We’ll get into how it’s utilized as more than a guide in later chapters, when we get to Closed Loop Fueling/EGO Corrections.  For now, tune that Fuel/VE Table right and let’s move on to ignition tuning! 

Ignition Advance Table / Spark Advance Table Tuning –  Now that the fueling needs of your car are dialed in, with a conservative ignition table in place during that tuning process, it’s time to turn up the wick and make this sucker make some power!  And as we’ll discuss more in later chapters, the majority of that power comes with ignition timing.   And unlike the MTV motto of the 80’s ‘Too Much Is Never Enough”, too much ignition advance is ABSOLUTELY too much!   You want to start a bit conservative, that would be lower numbers, with less ignition advance – and you want to sneak up on it.  Measure.  Add a degree.  Measure the impact.  Was it good?  Yes!  Add a degree.  Maybe you repeat this process a few times and then get a different result.  You add a degree and then you measure.  Was it good? No? No more power found?  Remove that degree, and you’re darn close to right where you want to be. 

This can happen pretty quickly on the dyno, in every usable cell in your table.  That means you’re not just choosing a simple range for the ignition advance to be dictated by the centrifugal force of the spinning of the distributor and a vaccuum advance—no, you’re dialing every cell in at every possible operating condition to make the MOST TORQUE that can be made EVERYWHERE.  You’re not adjusting anything based on the AFR/Air Fuel Ratio so much this time, except to monitor it for safe operation and to get out of the thorttle if something goes weird.  You’re adjusting the ignition advance based on the real time TORQUE output of the engine.  More timing should equal more torque, if you do indeed need that timing.  If you add timing and don’t make more torque, pull it back!  You do this throughout the operating range of the engine, cruise, part throttle, moderate throttle, etc.  Making sure your engine makes maximum torque in every cell you can safely reach at this stage.  The first time you’ve driven your car after doing this, you’re going to smile.  The driveability, throttle response, and part-throttle power/torque you’ll feel will be noticably improved and it’ll feel like an entirely different vehicle I bet.

Ideally, just as with fuel tuning (above), you’ll do this, or have this done, on a steady state, or load bearing dyno.  This is a dyno that doesn’t simply see how fast your vehicle can spin a big heavy roller, but that has a constantly fluctuating and adjustable brake on that roller, or on that hub dyno (ala DynaPack like we have).  That allows the tuner to hold the engine at a specific RPM, starting at low throttle/load, and tuning the lowest cell you or they can reach.  Then more throttle, tune the next cell.  Repeat until you’re up near full throttle, carefully wathing temperatures of course.  Then move to the next higher RPM column and repeat.  You build out a table quite quickly this way.  This is also the method used for complete VE/Fuel Table tuning above. 

You can generally reach the majority of the meat of your tables this way—but not 100%.  You’re not likely to want to hold the engine at a given RPM for that long at full throttle for instance, nor at the higher end of the RPM range.  Why?  Heat largely.  So after you’re doing doing this, for both the Fuel and Ignition Tables, you look at the ‘curve’ created—the rate at which the numbers are rising or falling as you go up, or to the right, in your table, and you estimate what should be in the rest of the table, erring on the side of caution (fuel slightly rich, ignition slightly retarded), to prepare for the next, and ultimate stage.  The Ramp Run. 


Ramp Runs – What most people think of when they think of a car on a dyno – VE/Fuel Table TuningAh, the fun part!  All the noise!  All the fury!  And if you and your tuner have done their job well, ALL of the Horsepower and Torque!!  This is the part when you find out what kind of monster you’ve created.  The Ramp Run.  This is what most everyone things about when they think ‘dyno run’ or ‘dyno pull’.  The dyno holds the engine for a second or three, at full throttle, and then lets it go and the engine accelerates as fast as it possibly can.  On a simple inertia dyno, the ramp rate depends on how heavy the roller is.  On a steady state/load bearing dyno with an eddy current brake or water brake – the dyno brake controls the ramp rate and it is adjustable on the dyno.  You can test fast ramp rates, and slow ramp rates. 

Start a datalog and number it sequentially and name it descriptively. You do a pull, exercising caution, listening, watching, smelling, watching your gauges, and only pulling all the way through if all is well.  And then you review the datalog.  First tuning the fuel, while the ignition at the top and right of the table (where the power is made) is still conservative based on what you know thus far in your efforts and wisdom.   You look at the Air/Fuel Ratio/AFR that the datalog shows at full throttle during the pull, you know what AFR you’re targeting at this point there, and you adjust your fuel table to make the AFR you get come inline with the AFR you want.  It’s pretty simple really.  And we’ll show you some tricks to get there faster. 

You repeat this process as you dial the fueling needs of the engine into to within a fraction of an AFR of where you want them.  I aim to get within .1 AFR.  Then you can turn on EGO Correction, using your wideband O2 Sensor in real-time, in combination with your AFR target table, allowing the ECU to look and ‘correct’ your fueling in real time if something gets a little bit away from the AFR you’re targeting.  Let’s say an injector gets clogged partially at some point in the future, this will help save the day.   

You will likely find you’ll make slightly better horsepower and torque as you dial these tables in.  Maybe 5% or so.  Don’t expect miracles in power for the fuel tuning.  You tune the fuel to make the engine operate SAFELY and EFFICIENTLY.  You tune the ignition timing to make the power.

Ramp Runs – What most people think of when they think of a car on a dyno – Ignition Advance Tuning Next up, Ignition Advance Tuning!  This is where the power is made.  It’s also where, if you’re dumb, you can melt your engine.  Don’t be dumb, mmmkay?    It’s really not that hard.  It’s been treated as a mystical black art for decades, but you’re going to see something you’ll love here soon enough.  Unless you’ve got another problem obscuring things (mechanical or otherwise) – it’s easy to know what to do.

It basically looks like this.  That very last power pull/ramp run you did tuning the VE/Fuel Table in the above section?  Make sure you have that datalog, and the dyno chart/log from that pull.   

Continue datalogging each pull, and number each sequentially and name each descriptively. You do a pull, exercising caution, listening, watching, smelling, watching your gauges, and only pulling all the way through if all is well.  And then you review the datalog AND the dyno chart after each.

You have your baseline pull.  You know how much horsepower/torque your engine made all across the wide-open throttle range at all RPMs above your start point.  Since you read and applied the above and further reading in this series, you believe you are conservative on ignition timing as a starting point—and you add a little.  Maybe 1 degree BTDC across the range you’re testing.  You do another power pull/ramp run.  Review the datalogs and dyno charts.  If adding that degree made more power all across the range, you’ll likely want to add more all across the range for the next test/pull/ramp run.  Then repeat.  Test, review logs/charts, adjust.  Keep the added timing where it added power and torque, remove any ignition advance you added if it DOES NOT increase power/torque.  Rinse and repeat until you’re making all the power you can make.  It’s pretty much that simple.  We’ll get in deeper though in a later chapter to really help you understand how to do this completely, safely, and with minimum wear on your engine.  I hope you’re as excited to grasp this and put it to work for you as we are to share this with you.  Stay Tuned….. 


>>> Read Chapter 4: Electronic Fuel Injection Options – Throttle Body Injection (TBI), MultiPort Fuel Injection (MPFI), Sequential Point Fuel Injection (SPFI), and Direct Injection (DI) >>>

<<< Go Back to Chapter 2 – Why should you convert to Electronic Ignition Control? <<<

*** Return to the Table of Contents ***

Click Here to check out our MADE IN THE USA Engine Management Systems!
DIYAutoTune Eagle Made in the USA


Copyright 2022 Hoffmann Innovations Inc. aka DIYAutoTune.com