Updated September 2022 by Jerry Hoffmann

Chapter 1 – Why should you convert to Electronic Fuel Injection?

“EFI is more user-friendly than carburetion and will help the more novice tuners. They can perfect the combo on the dyno, then the EFI will self-correct for atmospheric conditions. After a short learning curve, EFI actually levels the playing field. Anyone can learn to tune an EFI” 

Warren Johnson, Pro Stock Racer – Motor Trend January 1999 – More than 20 years ago. And it’s only gotten better.


So, first off, why wouldn’t you want to take FULL CONTROL of your existing Fuel Injection system, or convert from Carb to EFI?  For you Factory EFI guys, trust me– there’s no more powerful tool for you to take hold of!   For some of you carb guys, I get it, maybe you like the appearance under the hood of an old school carburetor. I can understand that, but you might have other things you may want to consider, and we’ll get to that in a moment. Maybe you are afraid of the effort involved in converting to a modern MPFI Electronic Fuel Injection system. Or perhaps you’re concerned you may not have the computer skills, or wiring skills, or the hands on mechanical skills needed to implement computer controlled electronic fuel injection and ignition control. These may be valid concerns for some, but for the vast majority of you—you have what it takes. When I (Jerry Hoffmann, founder) started this journey myself, I had never worked on an electronic fuel injection system myself. I had computer skills on a PC, and I had worked on cars – mostly just to keep them running on a budget but also doing some bolt-on performance improvements, You know maybe intake, headers, exhaust, the typical stuff an 80’s kid might have learned as he drooled over the performance aisles of Pep Boys and Autozone, but then made his way empty handed over to the fuel, air, oil filter section and bought what he came for just to keep his hoopty on the street. Eventually I saved my teenaged/early 20’s dollars up and was able to buy that Edlebrock carburetor that I never quite got dialed in right on my ‘79 Camaro, and added a set of used headers I bought on the classifieds, etc. I had to start somewhere, as we all do.

How did I get from there, to here? I read. And then I read some more. And then after that, I read some more. I read every book I could find on the subject of Electronic Fuel Injection, Turbocharging, Supercharging, etc. And along and in the middle of that journey, I also read the official MegaManual. The documentation for the original MegaSquirt-I System, back in 2003-2004. Back in the early days. I read that manual cover to cover, and a decent amount of it, maybe 40%, didn’t make sense to me. I read it again. Now I understood 75% of it. And again, it’s starting to click, I think I’ve got 85 or even 90% of this making sense to my pea-brain at that point—and throughout this process, I wasn’t just reading, I was beginning to DO. (somewhere along this timeline I also attended an in-person EFI training class in those early days, and that was the first time I had live tuned on a dyno, with the instructors oversight, of course—a great experience!)

So yes, I didn’t just study, I started to DO. That‘s when it all clicked that much more, when I put my hands to it. I ordered my first MegaSquirt-I system, got all the parts together, and assembled it. You don’t have to do that. I’m currently not planning to cover the DIY ECU Soldering and Assembly parth in this EFI Tuning Guide. That is still a very viable option- you can still build a MegaSquirt-2 or MegaSquirt-3 Engine Management System from a box of parts, and we’ll be glad to provide those parts to you and to guide you in that process. You’re trading elbow grease for not just cash, but for education—and while we will guide you, you will in large part be educating yourself. This guide will be a key part of that, but we’re starting at AFTER the ECU is assembled to properly fit your vehicle in this guide. I recommend for easiest entry and to reduce your effort and learning curve, that you start with an assembled and ready to fit your engine system such as the MS3Pro Evo or Ultimate, or perhaps the super affordable MicroSquirt AMP’d Engine Management System if that is fitting for your project, needs, and goals.  


So I didn’t answer the question yet, did I? Why should you convert to Electronic Fuel Injection? Read on…. 


Everyone of us that has ever owned a carbureted vehicle and driven it regularly, knows that the system is dead simple. It’s a toilet bowl that sits on top of your intake manifold, and all things said, it does a decent job of metering fuel for your engine if it’s perfectly tuned. A DECENT job, if it’s PERFECT. For many of us, that’s not enough. If it’s only DECENT, then it’s half-fast. Half-Fast. Say that 5 times fast. I’m not interested in half-fast. I wanna put my whole fast into it—I wanna be whole-fast. And whole-fast doesn’t sound funny when you say it 5 times.  


Electronic Fuel Injection (EFI) and Ignition Control – What are the advantages? 

Easier starting, especially when it’s cold. A fuel system that’s primed, up to pressure, ready to fire at the first twist of the key. Amazing, crisp throttle response with an engine that’s ready to roar without hesitation at the slightest tip-in of the throttle.  Tunability both now and for any changes you EVER make to the vehicle in the future, you’re ready, and you know how.  And plenty of other reasons.  We’ll get into some of them deeper as we continue here:



Yes there’s a little bit of a process to get there, and no, there’s no magic EFI system that will perfectly ‘just do it for you’ without you putting a little skin/effort into the game and learning some new tricks along the way. But once setup properly with quality components and proper wiring, there is no more reliable method of properly and consistently metering fuel and controlling ignition timing than a quality Electronic Fuel Injection and Ignition Control System. And those things you’ll learn along the way I PROMISE you will ROCKET you forward in your knowledge and understanding of yours (and any other) hot rod. You’ll know what the engine needs, and how to give it what it needs. You’ll know how to investigate and troubleshoot any issues you run into now and forevermore with the system giving you a clear view into what’s going on inside of you engine, or at least a very strong hint. And we can teach you how to read those hints. Read on….

Reach in the window when the car is dead cold on a frigid morning, twist the key, and in a revolution or two the engine roars to life. Idle up automatically to put a little heat in the engine, and as it warms up, smoothly bring that idle down to a low and stable rumble, or if you like the lope… you can make it do that too. It’s beautiful to take a ¾ race cam (yes, joke intended for some of you) and make that sucker idle like your grandmas brand new Cadillac. Or, perhaps even at the flip of a switch, make her lope, lope, lope….. if that’s your thing.  


Perfect and Flexible Tunability

At ALL rpms and load ranges, no matter the engine speed (RPM), no matter the throttle position, no matter how quick you stab the throttle

2D Naturally Aspirated VE Fuel Table
Naturally Aspirated VE Table / Fuel Table from a MegaSquirt/MS3Pro ECU

A carburetor has what, a couple stages of fuel delivery? A jet or two. Typically a pilot jet, and a main jet. A 4-barrel carb may have 4 jets, two for the primaries, and two for the secondaries. That’s typically what you’re dealing with. 

Is that really ideal? While yes, there is some magic in the venturis and overall, for what it is in all it’s simplicity, a carb can do a remarkable job of making that engine run DECENT.  Half-Fast. (Yeah, you remember what that means.) The reality is that with an Electronic Fuel Injection (EFI) System, with a simple to tune 12×12 fueling table typically known as a VE table (Volumetric Efficiency) that gives you, more or less, the ability to tune 144 different ‘jets’ electronically, you can get the tune spot on, everywhere! 144 jets!  WHOA you might say… that’s a whole heckuvalot of screwdriver twisting! And can you imagine cleaning all those suckers out when they gum up? YOU DON’T HAVE TO if you convert from carb to efi! And it’s easy. It’s a tickling of the keyboard, inputting a different VE number RIGHT where you need to make a change, and nowhere else.

What? You’re just a little richer than you wanna be when cruising right at 2500rpm and 30% throttle (throttle generally measured in vacuum present, or direct throttle position in some cases)– No Problem. Go directly to the cell, or cells, in your Fuel/VE Table, and make that little adjustment. It’s a little rich, running at 13.5:1 in this area while cruising? Easy peasy—pull a few percentage points of VE out of the cell/cells at that point in the table, and watch your AFR come closer to what you’re looking for. Maybe that’s 14.7:1 for a gasoline engine at stoichiometric (stoich for short), or maybe that’s 15.3:1 under cruise as you tune with a bit more focus on maximum fuel economy and efficiency. Pull a little fuel out with a tickling of the keys, and watch the Air/Fuel Ratio (AFR) come right to where you want it. That first adjustment brought it closer, but not quite where you want it? Pull a little more! Now… I’m talking fine tuning above here. If you go through the exercise of dialing in your VE/Fuel Table up front, either in real time driving on a closed/safe course, or on a dyno—you will dial all cells in at once, and you’ll be there. If you ever need to make a tweak though… there’s a little life hack that will save you time and make you look like the stud genius that you are.  

VE Table / Fuel Table with common areas of operation identified - idle, cruise, overrun/decel, moderate and heavy throttle

Take a look at the image above—this is a typical 12×12 Fuel/VE Table, with the general areas of the table highlighted. Idle. This is where the car spends it’s time warming up and sitting at idle once warm. Cruise. This is where you want to tune for maximum efficiency and fuel economy, as well as minimum emissions (yes, you can do that too!). Moderate throttle reaching higher load areas and higher RPMs than you’re likely to reach when just cruising.  Then the Heavy Throttle/Power up across the top and heading right—this is where the engine operates when you give it the beans and punch the throttle, and you want to operate at a different, richer Air/Fuel Ratio (AFR) here that gives the engine the fueling it needs to make maximum power with maximum reliability. We’ll get into that more later, but on most naturally aspirated engines that would be in the 12.5:1 – 13:1 range where you’ll make maximum power, safely, at full throttle. That’s different of course on a supercharged or turbocharged engine. On a forced induction engine like this, you’ll still operate at cruise in that 14.7:1 to maybe 15.5:1 range generally, and you can still get excellent gas mileage, driveability, and emissions. But when you drop the hammer on that right foot switch (that would be the throttle) you target exactly what’s needed to feed that boost the fueling it needs to make maximum power AND reliability.

8psi of boost? Maybe you’re targeting an AFR of 11.8:1 perhaps.

15psi of boost? You’re probably sitting right about 11.5:1.

More? Well… that’s going to depend on the combo, compression, fuel used, etc—but we’ll you the TOOLS and KNOWLEDGE to nail it. And the truth is, those are factors even at those lower boost levels, but there are some pretty good rules of thumb, and we’ll show you.  

Matt Happels Humorous Spark Table
Matt Happel’s humorous take on the different areas of operation on the Fuel, and/or in this case, Spark Table.




Efficiency, and emissions controls are obviously the core reason that OEMs began moving over to Electronic Fuel Injection EFI in the first place. With a desire, and with pressure upon the to increase that desire, to make engines and ultimately vehicles operate as efficiently and emissions friendly as possible. Better gas mileage. Fewer harmful emissions. And the good news it, it worked. And it can work for you too. You can dial your project car, your Pro Street Hot Rod, your Restomod, even the rowdiest of drag race cars, or land speed cars, road car cars, etc in to make maximum power with NO SACRIFICES. You can still operate that vehicle at, relatively speaking, the friendliest emissions levels possible, and with the best fuel mileage possible, while still making maximum power, making two times, three times, four time the factory power levels or more – and you can can it in a way that will be safe for your engine’s longevity while minimizing emissions and maximizing fuel economy. And you can ONLY do that with Electronic Fuel Injection and Ignition controlled by a modern Engine Management System that monitors all of the needed inputs to know what is going on with the engine to determine in real-time the best way to operate that engine in order to provide the best results in all areas. It’s just a fact. Computers have contributed to so many things in the last number of decades, and this is one key area where they have contributed in a hugely massive way.  



Horsepower. That’s what brought you here isn’t it? It’s certainly what lead me down this path all those years ago, and continues to. The ability to drive a well mannered car that, when I drop that hammer will RIP me back in my seat and make anyone else in the car pucker up and hold the heck on. Whether you are a drag racer, road course racer, autocrosser or whatever motorsport you’re into- there’s just something about a roaring engine and tire smoke. Whether it’s a small lightweight and balanced car that can rip up the corners with 253whp and 232wtq like my little ‘91 NA Miata, or my 1000+whp Land Speed Race Car based on a 1991 S13 Nissan 240sx that I’ve been blessed to set probably close to 30 land speed records in at up to 217.39mph, and continue to hold 13 of those records with the ECTA at the old Ohio track. I love horsepower. I love Torque. I bet you do too.  

A 7 Second Car With AC, Power Steering & Over Drive - Jonathan Coleman New Edge Mustang MS3Pro EFI
Jonathan Coleman’s MS3Pro Powered Ford Mustang

And there is no better way than Electronic Fuel Injection to max MAXIMUM horsepower and torque while managing all that power in a way that lets you put it down to the track surface you’re operating on. We can give you the POWER to make the POWER. That’s what a properly setup and operated Engine Management System will do for you. And on top of that we can give you the DATA to make the absolute most of your engine and vehicle, to be able to see exactly what’s going on inside of the engine and to make decisions that help you to maximize the horsepower and torque made, while making it safely. 

New Edge Mustang burnout with AMPEFI MS3Pro calling the shots
New Edge Mustang burnout with AMPEFI MS3Pro calling the shots

The ability to tune that engine for EVERY POSSIBLE operating condition – air /ambient temperature, throttle position, engine speed, engine load, track temperature even, and more – gives you the power to make the power. And we’d love to help you do that. I hope this series of articles, which will grow over time so keep checking back to that Table of Contents as we add more – will help you attain your every goal in making the power you’re after. And making it safely. 

Tina Pierce's '66 Nova midnight burnout
Tina Pierce (ala Street Outlaws fame) in here MS3Pro Ultimate controlled 1966 Nova she and husband/builder David Pierce just recently unveiled….


Engine Safeties 

That old carburetor does a decent job of simply making that beast move, doesn’t it? I mean, you might sometimes have hard starts and the fuel mileage might not be what you’d like, but it’ll move, right? Aside from all of the benefits of EFI listed above, and the others I haven’t gotten to yet—did you know a a Carb to EFI conversion using a modern Engine Management System like the MS3Pro Evo, or MS3Pro Ultimate, can use all of the information it gathers from it’s various sensors and inputs to not only control your engine. It can also use that information to make sure your engine stays safe, even, and especially when you’re pounding on it. You know that ‘check engine light’ that every modern EFI vehicle has? That can, depending on the error/code that’s been triggered, modify how the engine runs and/or, if needed, shut the party down entirely, if the issue is bad enough it could cause damage to your engine, thereby saving you a costly repair? Yeah…. MS3Pro Engine Management can do that too. But unlike an OEM ECU, you control what safeties are in place, and how your Engine Management System responds to various conditions. Engine Coolant getting overtemp? Yes we can flash a light on your dash ala ‘check engine light’, but that’s just getting started.  

Air/Fuel Ratio (AFR) Monitoring and Safeties will protect your engine from damage that could be caused by anything from a bad sensor, or a clogged injector, or anything else that causes and undesirable AFR for a given load and rpm. And you can have the ECU shut the engine down before damage happens. And that damage can be expensive if you don’t respond quickly. 

Rev limiters that stop your engine from overrevving at any time in operating allowing you to cut fuel, or retard ignition timing or cut spark altogether, or all of the above. 2-Step Launch Control Rev Limiters that allow you to control your launch speed to whatever RPM you’d like. Burnout (3-step) Rev Limiters that set a different RPM limit when you’re in the drag strip’s burnout box, or in a burnout competition (yes those exist!).  

Fuel Safeties/Failsafes that monitor fuel pressure in the fuel rail and can either adjust fuel injector pulsewidth (how long the injector is open) or can even shut the engine down to protect you from catastrophic failure. Your carburetor isn’t going to do that when your fuel filter clogs up or fuel pump starts to fail, is it? 

A failing air temperature sensor can be detected, and responded to. So can a failing coolant temp sensor. Or a MAP Sensor (Manifold Absolute Pressure Sensor). Notifying you and/or taking action to protect your engine and investment.  

Monitor your Oil Pressure in real time and if for any reason it’s not where YOU want it to be, shut the party down and save that engine. Clogged oil pickup, filter, or line? Save your engine.  

Knock Sensing allows for an Engine / Cylinder Head Knock Sensor to report dangerous pre-ignition and detonation and to respond to it by reducing ignition timing advance, or take other actions to prevent damage.  

And that ‘Check Engine Light’ that started the conversation here- it can be used to put your ECU and Engine into a ‘Limp Home Mode’ that lets you get back to a safe place to look into the issue and resolve it. Capture a datalog if you can on the way—it’ll help you, and our support team, to diagnose exactly what’s going on and what you can do to get back on the road (in your 100% emissions legal vehicle) or track, to continue your enjoyment of your race car, hot rod, or even your comfortable classic daily driver.  


Ease of tuning for future modifications/engine upgrades 

It’s never DONE, is it? That project car or race car, if you’re anything like me, there’s always something else I want and plan to do to it in the future to make it even better, faster, stronger. Start with an already heavily modified engine and give it exactly what it needs now and into the future as you modify your engine further.

That said — running a relatively stock engine to get started is NOT a bad thing at all. If you’re brand new to all this, it’s actually an EXCELLENT place to start. You’ll learn the ins and outs of Engine Management now, and it will continue to pay dividends for the rest of your life. Not just on this car/truck/boat/whatever– but on every vehicle you ever play with for the rest of your life.

You’ve got buddies that know everything about everything, at least if you ask them. But do they really know what an engine needs at all operating conditions to make maximum horsepower safely? Do they understand WHY, and know how to correct for, the needs that change on their engine when they install that new intake manifold, or exhaust system, headers, camshaft, cylinder heads, or forced induction setup running some nasty turbo or supercharger?

You will. You’re on a path here that will take you further than anyone else that has NOT invested in understanding their engine and it’s needs, and knowing how to give it exactly that—what it needs. Now with your current mods, and in the future as you continue to modify that engine and vehicle.   

Turbonetics 83mm Turbo for my Land Speed 240sx
Me several years ago getting ready to lay down 1000whp or so… with a 6cylinder.

Or maybe a blower is more your style?  This is an oldie but a goodie ;).
Whatever modification you make to your engine, turbos, blowers, I/H/E, cams, WHATEVER IT IS!  So long as you’ve got your EFI System sorted out, you’ll be ahead of the game, and ready to make the power.



Bringing it all together 

Whether it’s a ‘67 Camaro drag car with 6.0 LS like the one sitting next to me now, or fully road legal and streetable comfortable hot rod that purrs like a kitten when it should and roars like a lion when you want it to—Computer Controlled Engine Management is the ticket. It’s the way to attain all of the things you’re after in a high performance car or truck, or even a Sunday driver that just needs to be dead nuts reliable.

And fast.  What a blast it is to go to the racetrack, whether we are racing ourselves or supporting others, and to come home with the win!!!  (Especially when the event is sponsored by your competitor yet your product takes the top spot)

Horsepower Wars View from the VIP Box
Let’s Go! Horsepower Wars $10k Drag Shootout Finals – Yes, the MS3Pro controlled Camaro built by a bunch of crazy Aussies known as ‘Team Enemies Everywhere’ won it all!



Tools – the most powerful you have ever held in your hand.  

Auto Mechanics Tools

You like tools, right? You like the capability they give you to modify something, to fix something, to make it the best that it can be and to keep it that way. That’s what we aim to give you. Electronic Fuel Injection (EFI) and Electronic Ignition Control will put into your hands the most powerful tool you’ve ever used or experienced in your automotive/hot rod/racing journey. Having the know-how and the ability to control and monitor and even review later in datalogs exactly what’s going on with your engine will give you not only performance abilities you’ve never known before, but the diagnostic/problem solving tool that’s been missing in your toolbox. There’s quite honestly just nothing quite like it.  


There ain’t nothin’ to it but to do it!

Now get at it! Thanks for including us in your journey! 


>>> Read Chapter 2: Why should you convert to Electronic Ignition Control? >>>

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