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DIYAutoTune.com Frequently Asked Questions (FAQ)
Technical Articles that should really be a part
of this FAQ, but would make it too huge!
Understanding the MegaSquirt Engine Management System and
choosing a system that is right for you:
What the heck is a MegaSquirt?
|The MegaSquirt line of Engine Management Systems
are Do It Yourself (DIY)
systems capable of full standalone engine management a a fraction of the cost of
the what the 'big dogs' charge. They were designed with education and
performance in mind, so that the do it yourselfer could learn the in's and out's
of engine management and tuning, while learning a good bit about electronics in
the process if you choose to build the unit yourself. What you end up with is an incredibly performing EMS that you
built yourself for ultimate bragging rights when you leave your buddies behind
as a speck in your rearview mirror. And you did this for a quarter to a
the cost of a 'big name' retail standalone ECU.
Building and installing a MegaSquirt EMS will require that you do some
homework. Some of the questions and answers below will help to guide you
on where to start this and how to go about it. You will learn a lot in the
process and if you so choose you will come out of it with the knowledge to
properly tune your car for the current configuration you have now, and for any
future power combo you can dream up and implement. There is no limit to
what you can do or to how much power you can make with this engine management
system. We know right now of a MS user running low 10's (10.08) in a 5000lb
4x4 truck making over 1000hp and 1000lbs/torque to the wheels (turbo/nitrous)
who took first place in his class at Hot Rod's Drag Week 2005 and 2006. he won a high
dollar ($2400+) big-name EMS system in the 2005 contest, he quickly traded it away to
stick with his trusty ole' MegaSquirt 1, which he has a total of around $200 invested in.
We've got another customer making about the same level of power now on one of
these units on a Land Speed car he runs out at Bonneville. Again with an
MS1 running the MS1/Extra firmware, he holds a world record in his class at 240
out Gary Hart's car out at this link). Another customer we've been in
contact with recently has a MegaSquirt 2 in his rear-engine dragster. He's
running consistent 8.8 ET's in the 1/4.
This MegaSquirt thing is no joke.
Where do I start?
|Read. Then read some more. If you skip this step you will be
asking questions later that you could already know the answers to.
always glad to help though as this is a DIY based system some of the burden
does fall on the user to do their homework, the big dogs charge an extra $2000+
for their systems to do some of the homework for you. We'll help you with
your homework for free, but you've got to come up with the final answer.
Start with our "Which EFI system is right for me?"
link on our site here:
Which EFI system is right for me?
Then read, cover to cover, the MegaManual at that same link:
(you can skim the assembly section)
Then read about what is known as the MS/Extra firmware.
This is a free firmware update for the MS1 and MS2 that greatly expands the
featureset of the ECU, highly recommended.
MS1/Extra Features and Documentation
MS2/Extra Features and Documentation (includes MS2/Extra for
MicroSquirt/MicroSquirt Module, and DIYPNP usage)
Features and Documentation - (All MS3 ECUs use a single firmware
branch, and it's written by the 'Extra' developers.)
Now that you've read up on things start lurking around and/or asking any
remaining questions on the MegaSquirt Support Forums at
(Extra forums, advanced topics)
www.msefi.com (basic assembly guidance and support), there is so much
helpful information at these two forums that it's insane. The search
feature is your friend. Try searching for your vehicle or engine, 'RX7',
or 'Subaru', or '4AGE' and then go through the threads that are returned.
There are a ton of very helpful people on these forums that will bend over
backwards to make sure your project is successful, IF they can tell you've 'done
your homework' and that you're not expecting them to do all of it for you.
Questions like, "My car has an optical crank sensor in the distributor with one
hole for each cylinder, spaced evenly apart. Will the MegaSquirt-II work
with this signal?" will usually get very quick and helpful responses. On
the other hand, questions like "What do I need to make my 1967 Sooper Dooper Pooper Scooper
scoop poop at an amazing rate of speed?" generally get ignored
because it's obvious the person didn't put much effort into helping themselves
and that they are hoping someone will just pour out a magical answer for them to
help their Sooper Dooper Scoop Poop go faster.
Another link you might find interested--
- This site allows users like yourself to proclaim their MegaSquirt'd
success to the world, often with details on exactly how they implemented
the system. It's organized by vehicle manufacturer so it's easy to
find others with similar vehicles to your own.
If you don't know the right questions to ask, keep reading.
You'll get it.
You can also
Contact Us and we'll
do our best to assist you. We've got three full time tech support guys on
the team, ready and waiting (actually, they're not waiting, they're probably
digging through a couple hundred emails right now), but they get back to you
fast! Please see the list of questions below that will
help us to help you. The more prepared you are and the more you know about
your car and your ignition system the better off we'll all be and the faster
we'll be able to get you up and running!
What do I need?
|Another question that doesn't have a quick short answer... but the quick short
answer is: An ECU (there are a few options here of course), a stimulator (95% required),
and a tuning cable. Optionally you may need a USB-Serial Converter if your
laptop doesn't have a DB9 serial port, and/or a Wideband O2 system such as the
Innovate LC-1 or LM-2 (with or without a dash mount gauge) which will make tuning
your Air/Fuel Ratio SO much easier and more accurate that you'll be glad you
spent the couple of bills to do it.
Click Here to see a page
together to assist people in these decisions-- It doesn't cover all of
our products but
it does cover some of the more commonly requested options at a high level and provides
some idea of pricing (check our catalog for exact prices of each
component). For a complete product list, to
validate current pricing and/or to place an order go to
How difficult is it to assemble a MegaSquirt
takes most people new to electronics assembly 6-10 hours for their first
time assembly of a PCBv3 ECU, a bit less for a PCB2.2, and the
stimulator (which you should do first) is very simple and takes maybe an
hour to assemble for a first-timer. I'd recommend going to
www.google.com and querying for 'Soldering
Technique' and reading up a bit, and maybe pickup up a cheapo practice
kit if you want to practice your technique a bit before starting in on
the MegaSquirt. Check out Youtube for some good solder technique
like this one. We do often recommend you build your own MegaSquirt at least the
first time around as it will familiarize you with the hardware
particularly if mods are going to be required for your
This way it's not all new to you when you get to the mods needed for
Note we also offer all of our systems fully assembled
if you'd prefer to skip the assembly phase.
"It was high counsel that I once heard
given to a young person: Always do what you are afraid to do."
-Ralph Waldo Emerson
"Whether you think that
you can, or that you can't, you are usually right"
"Can't never could do nuthin'"
Carter (my stepdad when I was growing up, whenever I'd say I can't do
relevant quotes here:
"It was high counsel
that I once heard given to a young person: Always do what you are
afraid to do."
-Ralph Waldo Emerson
"Whether you think that you can, or that you can't, you are usually
"Can't never could
-Paul Carter (my stepdad when I was growing up,
whenever I'd say I can't do something)
I have a (insert year, make and model here), what exactly do I need to order
for my car?
|We'll be glad to help you spec a system for your car but
we'll first need some
information from you as we unfortunately don't have hands on experience with
every car out there. Below is a list of the questions we will generally
need answers to in order to assist with this. You can find this
information in service manuals for your car/engine, on message boards and
enthusiast sites, or sometimes by tearing into your ride and looking. It
will be a big help if you've followed the steps in the 'Where do I start?'
section above so that you have a pretty thorough understanding of the MegaSquirt
line of Engine Management Systems and you may find that you've answered your own
questions by the time you've done this. At any rate these are some of the
questions you will need to ask yourself, and that we will need to know the
answers to in order to be able to assist you:
(Please try and answer all questions as the two most people skip (3&4) are
the most important for ignition control!)
- What year/make/model/engine/tranny? (Pretend your at the parts store,
ordering a starter.) If this isn't the original engine/electronics
let us know that too.
- Are you looking to control fuel only, ignition only, or fuel and ignition?
Is there anything beyond these features that you are looking to
control - fans or boost, for example?
- Is it important to run sequential injection for this project, or
is bank to bank fueling OK? (See our notes on
sequential injection if you're not sure.)
- What are the engine details (type, number of cylinders, previously fuel
injected or carb'd?)
- What type of ignition system does your car run? Is there a distributor?
Coil pack? Coil on Plug?
- What sort of sensor(s) does it use to trigger the ignition?
Variable reluctor (magnetic pickup)? Optical? Hall effect? Old
fashioned mechanical breaker points? Are the sensors triggered by
trigger wheels on the crankshaft / flywheel, distributor / cam, or
- How many teeth / windows / slots and are on the crank or
distributor trigger wheel? How are they arranged? (Equally spaced,
missing teeth gaps, etc)
- Does this engine have a fast idle valve (IAC)?
If so, how many wires are connected to it?
- Rate yourself 1-5 on technical confidence in yourself. 1 being "I
can't paint by numbers" and 5 being "I can probably build a car from scratch
if I have the right documentation, and I'm resourceful enough to do some
research and find some of my own answers." We need to know this as some
of the 'less traveled' roads will require you to make modifications that in
some cases we haven't performed ourselves yet and based on this response it will
help us to know whether this type of solution is for you or not. I
challenge you to 'stretch yourself' a little bit. You won't ever learn
anything (about yourself and your abilities) if you don't try to do things
that you're not quite sure you can do... and then find that you can.
- Are you looking to build your own ECU from a kit or buy a pre-assembled
- Are you open to retrofitting a different ignition system such as the Ford
EDIS distributorless system or one of our crank trigger kits if it is determined that the MegaSquirt will not
properly (or easily) control your factory ignition system? Many factory
systems MegaSquirt can simply take control of, some it cannot. EDIS to
the rescue! It's cheap, simple and works great!
If you can cut and paste the above list into an email and answer all
questions it would be very helpful to us-- otherwise I'll just have to ask you
the same questions more than likely in order to best be able to assist you.
Also-- Here is a
page we maintain with links to installation documentation for various different
vehicles that we've found around the web-- This is a good place to check for
information that just might help you 'squirt your ride. Even if it's not
an exact match there is much to learn by looking over other's installations and
If you find or write more install docs that we
can add here please let us know.
What is the difference between the MegaSquirt PCB 2.2
/ PCB 3.0 / PCB 3.57?
all three able to use the MegaSquirt-I CPU as well as the MegaSquirt-II
and MegaSquirt-III daughterboards, but they are based on different versions of the circuit board
and as such there are different features .
You can click on any of the headings below to view an example of the product
The v2.2 board dates back several years, it's
the least expensive of the currently available options, and the least
developed. It's a great low budget solution that has served many people well
(and continues to).
The v3.0 board has a lot of improvements made to
it to reduce electrical noise and increase robustness (damage resistant), as well as make
the board easier to expand.
All of the improvements with the V3.0 board are listed here.
The main high level differences are that the
uprated flyback circuitry is included so you can run low or high
impedance injectors, there are several improvements to make the board
more robust and harder to damage in the event of a mis-wire or overload
event. A prototyping area was adding to the PCB, and several changes
were made to prepare the board for the MegaSquirt-II and MegaSquirt-III
The v3.57 board's major claim to fame is it's
'surface mount (SMT)' design. Otherwise it is almost
identical to the v3.0 board and the above information on the v3.0 board
fully applies. The only other major differences are:
A) the addition of a PWM capable idle control
transistor allowing control of a PWM idle valve or a standard on/off type
FIDLE valve without need for modification. This was a common
modification applied to the v3.0 board and is no longer needed on the
B) the addition of a DB15 connector next to the
DB9. By default this doesn't do anything, but is there to allow
for extra I/O for modifications. It takes the place of the
externally viewable LEDs, which are now internally surface mounted on
C) Several signal pads have been added making
common modifications easier.
D) The prototype area was sacrificed (removed)
to make all of the above possible.
In general, if you're
looking for the cheapest option possible, the
PCBv2.2 makes sense. Chances are you'll mate an MS1 processor with
it in this case, such as with our MegaSquirt-I kits and assembled units.
Otherwise, if the small difference in price is worth it to you to go
with a tougher and more featured board that was built with expansion in
mind, the v3.0 or v3.57 boards make more sense. We offer
MegaSquirt I's, II's, and III's using these two boards. Some
prefer the thru hole v3.0, and some prefer the v3.57. See the
above to decide your preference between the two.
How big is the MegaSquirt case?
MS1 and MS2 cases are is 6.2" x 4" x 1.75" with mounting flanges on each end that are
about .5" long, so total length including flanges is about 7.2".
The MS3 cases are a little taller, about 6.2" x 4" x 2.6", again with
mounting flanges on each end that are about .5" long, so total length
including flanges is about 7.2".
How does a MegaSquirt compare to having my car 'Chipped'?
|It is possible to get many of the same performance benefits of the MegaSquirt
by having your car chipped IF the tuner chipping your car has your car
onsite and custom tunes the map for your specific configuration on a steady
state/load bearing dyno.
If you are not the hands on type, or you don't plan to EVER modify your
car/engine again, then this is not a bad option. If you do ever mod your
car again it will likely need to be re-chipped, on a dyno by a qualified tuner,
to get the maximum performance out of it. If you simply send your ECU off
to a chipping company who is supposed to load a map on your car, or buy a canned
tune online to load on the chip yourself you're likely not going to get
the results you're after. In either case that tune/chip was NOT
designed specifically for your car on a dyno by a qualified tuner so you
are simply not going to get the maximum performance possible out of the engine.
They simply can't do it-- they have to make a lot of assumptions with no
scientific testing on YOUR car.
However, if you really want to take control of things, if you do have plans
to further modify your car and you don't want to have to pay someone to rechip
it every time you mod it, and if you are open to learning something in the process then
by all means a standalone EMS is the way to go. And there is no more
powerful system per dollar spent than the MegaSquirt, in fact even with the
affordable price out of the picture the MegaSquirt line of Engine Management
Systems rival the featureset of many
aftermarket 'high dollar' systems. Particularly the newest MS3 system with
MS3X Expander board. We're talking 100% of the functionality of many
high-dollar systems, without the high-dollar price tag.
Don't I need sequential injection to make big
power? Does the MegaSquirt offer this?
Sequential injection attempts to only spray fuel while the intake valve
is open for the cylinder that is about to fire, which in most cases is
only possible at low engine speeds between idle and low speed
cruising. It can have benefits in emissions, drivability, and fuel economy at
these low engine speeds.
Batch injection (which is what the MegaSquirt-I and and most MegaSquirt-II
versions do) does not attempt to spray
only when the valve is open. It's a fact that at higher engine
speeds you won't have enough time to spray all fuel while the valve is
open, making this somewhat pointless, particularly for
a performance oriented application. At these higher
engine speeds 99% of sequential systems (exceptions being race only
systems with super massive injectors) cannot spray all of the fuel
needed while the valve is open anyways, and sprays it both while the
valve is opened and closed, very much like a batch system such as the
MegaSquirt I and II. We've dyno tested several cars with using
batch fire and sequential injection on the same motor. Peak power was
the same without using individual cylinder tuning. The sequential fire
setup did run a bit more smoothly at idle and at light throttle angles,
That said, the MegaSquirt III system
with the MS3X Expansion board or MS3-Pro will do full 8 cylinder sequential fuel
and ignition. If you're looking for the absolute best possible
emissions and fuel economy, as well as the ability to fine tune each
cylinder individually, then the MS3 system is the way to go.
There is generally no significant performance difference with a sequential system
over a batch system unless you use individual cylinder tuning. There can be minor emissions and fuel economy
benefits at very low speeds though. If your tuning budget allows for
individual cylinder tuning, it may be possible to pick up 3-4% more
power depending on how much cylinder to cylinder variation your engine
Is the MegaSquirt Engine Management System just for making more power?
Or can I get better gas mileage out of it too? What about emissions?
MegaSquirt Engine Management Systems are most often installed in the pursuit of
power gains, but often economy gains are just a possible. In fact due to the
nature of programmable fuel injection usually you can achieve some of both,
power when you are on the throttle, economy when you are lightly cruising around
town. It's really all in the tune. The factory will have tuned your
gasoline engine to
run around at 14.7:1 air/fuel ratio (AFR). This is the 'chemically correct' or
'stoicheometric' (stoich for short) air/fuel ratio (AFR) which basically means this is the
air/fuel mixture at which the most complete burn of the fuel will occur. It's
also the proper mixture for the catalytic converter to best be able to do it's
job, in other words, your car comes tuned from the factory for reduced
emissions. If your goal is power, you'll be tuning a somewhat 'richer' mixture
than this, for a naturally aspirated car this is usually in the 12.6:1-13:1 range
under throttle. For economy you'll tune somewhat leaner than this, as lean as 16:1
possibly if your engine runs well there, or maybe even a tiny bit leaner when lightly
cruising on the highway. That can lead to quite an improvement in highway
mileage over the factory 14.7:1 tune. Not all engines like to cruise this lean
so your 'mileage' may vary, our MR2 seems to love 16:1 on the highway-- We were able to get 34.5 MPG on an 1100 mile trip at an average speed of 70 MPH,
a decent increase over stock for sure! And one of the great things about
EFI is you don't have to sacrifice WOT power to do this-- that MR2 that's getting
better mileage than stock on the highway, also makes more power than stock when
I step on it-- it's an entirely separate part of the EFI map!
That said, if tuning for emissions is your goal you actually may be able to do a
better job than the factory did as well though your task will be tougher as
that's at the top of the factory's priority list. Areas you may be able to
improve: Often factory cars idle richer than 14.7:1,
and under power are again richer than 14.7:1, though they likely need to be
at wide-open throttle, with proper tuning there is likely room for improvement
in emissions and fuel economy.
Note-- All parts are sold for OFF ROAD RACE-ONLY ground-vehicle use
only. Aftermarket EFI/EMS systems are not for sale or use on pollution
controlled vehicles. Alteration of emission related components
constitutes tampering under the US EPA guidelines and can lead to
substantial fines and penalties. Your state/district may also have
specific rules restricting your tampering with your vehicle's emissions
system. In short, as stated before, our official policy has to be RACE
or OFFROAD USE-ONLY in ground based vehicles ONLY.
Bowling and Grippo have compiled
some excellent info on legality of aftermarket components on cars here
that you should check out as well. Click here to open a new window
with this info.
The MegaSquirt 1 and 2 ECUs seem to have only four injector output pins (or
terminals on the relay board) but they are labeled as pairs so this is even more
confusing, do I have two or four injector outputs? And how does either two
or four outputs allow me to run 6, 8, or 12 injectors?
the MS1 and MS2, you've got two 'banks' of injectors. Or two 'groups' if you will. You
can use one or both of them. With 1-6 cylinders one is fine, though you can use
both and generally would do so unless you were using the second bank for a
different purpose (staged injection maybe). With more than six you should share the load across both banks.
has two terminals that you bring together to a nice fat (like 14ga) wire that
then goes out to all of the injectors on that bank. So for an 8cyl for example
you might choose to run two banks of 4 injectors each. You'll run 12v to one
side of all eight injectors that's hot in the 'crank' and 'run' positions. Then you'll run
the 14ga wire out from one pair of terminals (one injector bank output) nearby
the injectors where you'll split that 14ga off into 4 smaller gauge (20ga
probably) short wire runs to the individual injectors. Do the same thing for the
The MegaManual's 'Sensors and Wiring' section has a
wiring diagram that shows an example of this for a 4cyl car. Same principle for
an 8cyl or even a 12cyl.
a link to the wiring diagram for MS1/MS2 that was just mentioned.
Note that when running a MegaSquirt-III, you can still run batch
injection if you choose, using the same wiring diagram as above.
However you can also purchase your MegaSquirt-III with the MS3X Expander
Board, and then have up to 8 channels of sequential fuel and ignition
outputs available. (Not to mention all of the other features this
enables, lots of I/O).
Check out the MS3X Wiring Diagram here.
Is there a central place where I can download maps that others have shared?
|Maps can sometimes be found on the
http://www.msefi.com forums that are similar enough
to be used as a base map for your vehicle but it's generally not encouraged to just grab
someone's map and run with it, as there are a few things to consider first. You want to
ensure their setup is as similar to yours as possible, including the engine,
ignition system, MegaSquirt version and firmware version they're
running. If they were running a different MS version, or firmware
version than you then
you can still copy the information from their map manually, but don't import it into
your ECU as it's very possible some of the data won't import properly into a
different firmware version. This could help you get started in the right
direction towards building your map.
Another thing to consider
(maybe the biggest), especially if the
ECU setup you're using required mods to control your vehicle's
ignition system, is are the mods you're using identical to the mods used
by the person that created the map? Are they using the same
ignition components (ignitors, coils, etc)? If anything is
different here their ignition settings could
be different from what you need, and could damage your coil or ignitor.
Things to watch out for are the SPARK OUTPUT setting (inverted or non)
and the DWELL settings.
The most important thing to remember is that
no matter how good so-and-so told you their map would work on your car, you are
still ultimately responsible for making sure your ECU is properly setup for your
car, and that your car is properly tuned.
That means looking over the map's settings BEFORE you start the car. Do the
ignition settings look right and does the ignition table look logical? Is there 60 degrees of timing at WOT, if so,
that's probably not right.... Then when you start the car you should
still treat it like you need to tune it yourself from scratch, you've just
hopefully got a good headstart. Tune the idle first, then slow
speed VE and ignition, cruise VE and ignition, and then work on up to higher
loads and finally WOT VE
and ignition. Read the MegaManual cover to cover.... again....AGAIN!!!
There are good books out there on tuning as well
such as the one recently published by our lead tech Matt Cramer and
owner Jerry Hoffmann (Click here to check it out).
This stuff is fun! But you do have to do
some homework. Best and most rewarding homework I've ever done though.
Idle Air Control valves versus Fast Idle Valves--- What does my car have and
how can I tell?
|Here's a way to figure it out-- on a cold morning, when
you start your car up on it's stock ECU it idles higher than normal right? That's because this valve
is partially open letting more air in to idle the car up so that it warms up faster. Now... if
you sit there until it warms up, does the idle drop back down to normal all of a
sudden? If so it's a FIDLE valve (generally two wires, ground and 12v+).
Alternately, does it
slowly idle back down to normal a little at a time, gradually reducing the idle
speed as the engine warms up? If so it's either a PWM or
stepper motor valve.
To determine if it's a stepper or PWM valve,
find the valve on your engine, it will be attached to the intake
manifold, either directly or via a hose. How many wires does it have?
Generally a PWM valve will have 2 wires, sometimes 3, and a stepper
motor IAC will have 4 wires, sometimes 6. The MS2/MS3 stepper circuit was
designed with GM/Jeep valves in mind, however it works great on many
different stepper IAC systems, including most all USDM, Euro, and
Japanese vehicles that use steppers, among others.
I'm considering an EFI conversion - converting my car from carbs to EFI-- what do I need to
Starting with the fuel system it will
need to be converted to a high pressure system suitable for fuel injection
(around 43.5 psi for MPI, less for TBI if you go that route), if you can get a
TBI unit (with TPS) that bolts to your manifold that may be the simplest route
(though their likely will be more power and better economy/emissions in a good MPI setup), otherwise you'll need to
buy or fab up an intake manifold and throttle body with TPS, fuel rails, etc.
We don't carry intake manifolds at this time, though we do carry many of the
fuel system components you will need, and of course the engine
management systems and accessories.
FOR FUEL AND IGNITION CONTROL-- We'd
suggest running a MegaSquirt-II, or MegaSquirt-III, using the PCB v3 or v3.57.
You'll need a compatible Crank
Angle Sensor to determine engine position and RPM from as well as some way to
fire the ignition -- with the MS2 this is generally a distributor based solution or
the Ford EDIS or GM DIS distributorless solutions which could be adapted to your
engine (most adaptations use EDIS which also uses it's own 36-1 Crank Angle
wheel which can be mounted on the crank pulley). You can read more about
ignition options in the MS/Extra documentation at
FOR FUEL ONLY-- You could run any of
the MegaSquirt ECUs, the MS1, MS2, or the MS3. We'd recommend PCB v3.0 or
PCB v3.57. Pickup up
your ignition signal from the negative terminal of the coil, run your IAT, CLT,
TPS, and O2 sensor inputs to the MegaSquirt, calibrate the MS to the sensors if
they are not GM sensors and start tuning.
If you haven't yet we'd again suggest taking
a look through the 'MegaManual' over at
and/or the MS/Extra version of the manuals at
http://msextra.com/doc/index.html as it will go into detail about
most aspects of the conversion/installation/configuration/tuning and help to
make things clearer.
Here's a list of what most people
would commonly pick up: We'll list what we see as 'required' and then some 'recommmended'
and 'optional' components. Then we'll provide a link that goes into some
detail on why we made these recommendations and that will also help you to decide on
the optional components.
(Note you can substitute DIY kits for the below to
save some cash and learn more about your EFI system, and electronics in general, in the process.)
Innovate LC-1 Digital Wideband Controller with Sensor
12' MegaSquirt Wiring Harness (MS1 / MS2 Ready) and possibly the MS3X
Harness as well if you're running the MS3X board.
MegaSquirt Relay Board - Assembled Unit
MegaSquirt-I Relay Cable (if you're using the relay board and cable,
you don't need the standard MSHarness12, see note in product description)
GM Open Element IAT Sensor with Pigtail
GM Closed Element CLT / IAT Sensor with Pigtail
USB to Serial Adapter - Works with MegaTune!
Here's the link I mentioned with more
info on each of the above--
Where can I find the MegaSquirt Schematics?
Using the Relay Board with the PCBv3, what do
terminals S1-S5 do?
This is the best way to go about this-- You can use the
schematics for the PCBv3 ECU and/or PCBv3.57 and the Relay board to trace it back. Here are the
Relay Board schematics and here are the
PCBv3 schematics and
Here's the quick answer though mapping these terminals back to the corresponding
pin on the PCBv3 ECU's DB37:
S1 = 25
S2 = 27
S3 = 29
S4 = 31
S5 = 36
With the MS-I these were unused by default, available as spare inputs/outputs.
With the MS-II and MS-III (legacy installation) S1-S4 are used for the stepper motor IAC, and S5 is the ignition
For more information on the Relay Board check out this
Note you can do the same cross reference for
the PCB2.2 ECU and the Relay Board, just use the
PCB2.2 Schematics. Though the pinout is of course the same...
MegaSquirt work with my stock ignition system???
|This is the most important thing to determine when attempting to control both
fuel and spark. In an ideal situation, you can take control of your stock
ignition system and call it a day. That is very common on
distributor based vehicles, and the variety of supported wasted spark
and coil on plug ignition systems is now very large as well,
particularly with the newer processor ECUs (MS2 and MS3). For some
ignition systems, particularly when used with MS1/MS2 ECUs, you may need
to do a bit of
modification to the MegaSquirt in the way of adding coil drivers or
input circuits (tach input) and such to set it up to control some ignition systems.
Here's a good article that will help you understand the basics here:
the MegaSquirt work with my
Stock Ignition System?
Note there are MANY factory ignition systems supported, with the list
MS/Extra docs for details.
If you do need to adapt a different ignition system to your vehicle:
Ford EDIS is a distributorless ignition system that's very easy to adapt to
just about any internal combustion piston engine out there -- you just need to
mount (weld or bolt) a 36-1 trigger wheel to your crank pulley and build a bracket for
the VR sensor to locate it next to the trigger wheel. That's the hardest part
and the only fab work. The rest is a bit of wiring. The EDIS system has an EDIS
module and a coil pack. The module is wired to the VR sensor and the MegaSquirt,
and also the coil pack. The MegaSquirt-II or MegaSquirt-III is what we would recommend for EDIS
control and will take full control of an EDIS ignition system easily.
Here are some links with more info:
Here's all the parts that are needed and where they can be found if you wanted
to dig them up yourself:
Here's the MS1/Extra EDIS documentation:
MS1/Extra EDIS manual
Here's the MS2/Extra EDIS documentation:
Can I leave my stock ECU in place to control
non-EMS related gadgetry, while letting the MegaSquirt control the engine?
you can-- This is what is known as a 'Parallel Install' and on some newer cars where the OEM is putting more and more
responsibility on the ECU (more than just an Engine Management role) you
may need to go this route. Some of the other responsibilities that OEM's are
putting on the stock ECU are gauge control, cruise control, auto tranny
You'd basically leave the stock ECU in place, and leave the stock sensor
inputs connected to it. Then you'd run a new CLT and IAT sensor for the
MegaSquirt (you can share these but it can be troublesome, read up on it
if you want to share IAT/CLT with the stock EMS), and then share the TPS and O2 signals between the stock ECU
and the MegaSquirt. You'll disconnect the spark output(s) from the stock
computer and wire the spark input to the MegaSquirt (pin24). You should
be able to share that signal in most cases. Next wire the MS spark
output (pin36 usually, depends on model and mods) to the stock igniter or
directly to the coil if the ECU is set up for direct coil control. Then
disconnect the fuel injectors from the stock ECU and wire them to the
MegaSquirt. This will basically give your factory ECU control of
everything but the engine, and give the MegaSquirt control of the
Note that's just a quick rundown, and not
necessarily in the order you might go about things. For example,
you might prefer to start with fuel control, go ahead and do all of the
above EXCEPT the spark output change (you do need the crank/cam signal input shared
with the MS at this point). This way you've got full fuel control,
but the stock ECU is still controlling ignition. You can dial in
your fuel map and get the car running good, and then move spark over as
well with this transition being much smaller than taking it all on at
once. Not to mention you'll know the MS ECU and the tuning
software MUCH better.
some may call this 'running the MS as a piggyback' though it's not.
A piggyback ECU simply manipulates the stock sensor signals to 'trick'
the stock ECU into performing differently. There is no trickery
going on with an install as described here, this is a full
standalone EMS implementation, we're just leaving the stock ECU around
to control the NON-EMS stuff. Call it a 'Parallel Install' as the
two computers are working in parallel each playing their part, with no
attempt at tricking each other by manipulating inputs.
Can I use the stock IAT and CLT sensors
with the MegaSquirt?
you can in almost every case-- the exception is that you sometimes
remove your stock IAT sensor when you remove your MAF/AFM as it's often
built into stock MAF or AFM on
many cars. If this is the case then you'll need to add another IAT
sensor to the intake tube, usually just before the throttle body, and
after the intercooler if you have one. The idea is to measure the
air temp as it enters the engine. After anything heats it up (like
a turbo/supercharger) and AFTER anything cools it down (intercooler,
meth injection, etc). You want the actual air temp of the air as
it enters the engine.
an article that shows how to measure the resistance curve of your stock
(or any really) sensors so that you can input these values into your
MegaSquirt EMS via the tuning software for MS2/MS3 ECUs, or via EasyTherm for the MS-I, to calibrate your ECU for your
Measuring and Calibrating your Coolant (CLT) and Intake
Air Temp (IAT) sensors
Help! I broke the pins on my MS-II
pins are Digikey Part# ED7764-ND.
How do I power cycle or reboot a MegaSquirt?
|These both mean turning the
MegaSquirt off and back on again. Some settings only take effect when
the MegaSquirt powers up. The latest versions of MS2/Extra and MS3
firmware will display a message in TunerStudio when you change a setting
that requires power cycling to take effect.
Assembled Units MS130-C and MS230-C
There are several 'optional' or 'choice required' steps during assembly of
the PCBv3 MegaSquirt units, how are the DIYAutoTune ECU's configured?
EMS's are setup by default as a fuel only EFI controller
running though they are running the current stable release of the MS1/Extra
firmware. These are configured to be
triggered from the (-) negative terminal of the coil by default. It is
fairly easy to convert them to be triggered from a Hall/Optical/Points trigger
if you prefer. Here are the steps to take:
- Cut out C12 and C30. Don't jumper them or anything, just clip the
leads and leave them out. (Assembly steps 50h and 50d)
- Jumper D1. You can remove the diode first, but you don't have to.
It's easier to just solder a little lead shorting both of it's legs together.
MegaSquirt-II EMS's are by default configured for fuel and
ignition control running the current stable release of the MS2/Extra firmware.
These are configured to be triggered from a Hall/Optical/Points trigger by
MegaSquirt-III EMS's are by default configured for fuel and
ignition control running the current stable release of the MS3 firmware.
These are configured to be triggered from a Hall/Optical/Points crank trigger by
default, and with the MS3X board added also support a similar Cam sensor input
allowing sequential fuel injection.
WideBand o2 / Oxygen Sensor Systems from
Why is a wideband o2 sensor better for tuning AFR than a narrowband o2
sensor? Isn't my 1/2/3/4/5 wire stock o2 sensor good enough?
|A wideband o2 sensor system will give you far greater tuning ability than a
narrowband sensor. The problem with a narrowband sensor is that it is only
truly accurate at 14.7:1 AFR. The factory will have tuned your engine to
run around at 14.7:1 air/fuel ratio (AFR) at cruise and light load conditions. This is the
'chemically correct' or
'stoicheometric' (stoich for short) AFR which basically means this is the
air/fuel mixture at which the most complete burn of the fuel will occur. It's
also the proper mixture for the catalytic converter to best be able to do it's
job, in other words, you car comes tuned from the factory for reduced emissions
and that's why that narrowband sensor is there. Therefore it will be
useful for tuning cruise Air/Fuel Ratio (AFR) only as long as you're tuning for
14.7:1 air/fuel ratio. However under Wide Open Throttle (WOT) you'll want to
tune for somewhere between 12.6:1 and 13:1 (NA) or richer for forced induction, and the
narrowband won't tell you anything useful at that range. Likewise at
cruise you may not want to tune for 14.7:1, maybe you want better fuel economy
at cruise and you want to tune to 15.5:1 or even a bit leaner possibly. Only a wideband can give you accurate feedback outside of the stoich
14.7:1 reading that NB sensors are designed for, and allow you to tune for best
power and best economy.
In short, a wideband oxygen sensor will give you
a measurement of your Air/Fuel Ratio from about 10:1 up to about 20:1
AFR allowing you to target exactly the AFR you're after at all times.
A narrowband can only tell you when it's 14.7:1, and is therefore nearly
useless for tuning.
Do I have the newer or older style LC-1?
Should I get it replaced if it's older?
You can skip this section if you bought your LC-1
after June of 2006.
First... the issue is that if there is a
voltage differential or any other cause that would pull your 5v output
to anything above 5v it could burn out the DAC on the older model LC-1.
Wired properly most people never had a problem with them but Innovate
decided to make the circuit more robust now and provided an
updated version of the product, and RMA'd any units that were damaged
due to the 'issue'. They were truly a class act in how they
The 'older model' LC-1's were up until about June
2006, in white/beige box. The new models were sold since then and
Innovate updated the packaging at about the same time to a blue/black
box and later still to a white/red box. The more definitive way is to determine which model you have
is to check the serial number.
The serial for the LC-1s
with the analog output fix are LC11188 forward and all LC-1s that start
with CLC. Note that in fall 2007 Innovate started using a
white/red box, these are still the new LC-1's, just using a different box design.
Bottom Line: Wiring it according to the docs is the most important
thing. Not just for longevity but for accuracy as well. You don't want a
voltage differential in your readings so you definitely want to ground
your LC-1 at the same point as your ECU (assuming you're feeding the
output back into the ECU) or datalogger if that's what you're using.
Then ground the heater ground to a separate point as per the docs. This
will make even the old LC-1's last forever in my experience....
See the FAQ entry below for more info on this.
How should I wire up my Innovate LC-1 or MTX-L?
the most part you'll follow the 'Quick Start Guide' that comes with the
controller to the letter. If you lost that or need a copy of it for some
reason you can download it here:
LC-1 Quick Start Guide for the LC-1,
LC-1/XD-1 Standalone Gauge Kit if you have the combo kit, or
MTX-L Manual for the MTX-L.
Here is what we'd like to add:
- Ground the controller and the MegaSquirt
together. This is to prevent a voltage differential and will
ensure accurate readings.
- The factory EFI system's fuel pump relay
often makes a good source for 12v switched power. This is a
required source for 12v, but often a good one...
- For the LC-1, wire the brown (analog out 2) wire to the
MegaSquirt's O2 input wire. For the MTX-L and LC-2, the default analog
outputs are reversed, so you'd wire the yellow (analog out 1) wire
to the MegaSquirt's O2 input wire.
For any LC-1 purchased after June2006, that
should be all you need to be concerned with when wiring it up.
THIS STEP IS ONLY ON 'older model' LC-1'S
as defined above (and below actually)!
Use a 470 ohm, 1/4watt resistor in between
the analog output of the LC-1, and the o2 input of the MegaSquirt.
So you'll wire the analog output from the LC-1 to one side of the
resistor, and then you'll wire the MegaSquirt 02 input to the other
side of the resistor, forcing the signal to pass through it.
- Blue Box or White/Red box LC-1's (started
shipping around mid-June '06) have an updated DAC that does not
require the 470 ohm resistor when used with MegaSquirt.
Another way to identify if you have this updated LC-1 that doesn't
need the resistor
is the serial number will be LC11188
or above, or the serial number will start with CLC on new models.
How should I wire up my Innovate LM-1 or LM-2?
the most part you'll follow the 'Quick Start Guide' that comes with the
LM-1 / LM-2 to the letter. If you lost that or need a copy of it for some
reason you can download it here:
LM-1 Quick Start Guide
LM-2 Quick Start Guide
Here is what
we'd like to add:
- If you are simply using the LCD display on
the LM-1 / LM-2 to tune your car you have nothing different to do.
However, if you are routing an analog output from the LM-1 / LM-2 into the
MegaSquirt you should ground the LM-1 / LM-2 and the MegaSquirt at the same
point. This is to prevent a voltage differential and will
ensure accurate readings. I've been know to clip the cig
lighter connector wire that comes with the LM-1 / LM-2 and put quick
disconnects on it, and install the same type of quick disconnect
connectors on the MS Harness so I can pull power and ground from the
same source it pulls from, ensuring the MegaSquirt gets an accurate
Note-- You don't ever need the 470 ohm
resistor with the LM-1 or LM-2.
How do I configure TunerStudio for the Innovate
LC series, MTX-L, or LM-1 / LM-2?
long time we guided customers on how to re-program their LC-1 / LM-1 /
LM-2 to output a slightly different signal from default. The goal
of this was to increase the resolution of the signal in the range of AFR
most users will spend their time in. What we used to recommend was
to program the output you were using to send a signal that represented a
10-20:1 AFR from 0-5v. While in theory this is great and does
increase resolution a bit, in practice it's not really needed and is
probably more trouble than it's worth for most users. The benefit
of this is almost immeasurable, so going forward we recommend leaving
the analog outputs on your LC-1 / LM-1 / LM-2 at their default settings
(which is 0v = 7.35:1 AFR, and 5v=22.39 AFR).
Then to configure the TunerStudio tuning software to allow your
MegaSquirt EMS to properly talk to your LC-1 / LM-1 / LM-2 do
With your TunerStudio
project open, go to:
File > Project > Project Properties and click
on the Settings tab
Under EGO O2 sensor, chose the right option
(Innovate LC-1 Default) for your wideband in the drop down menu and
click Ok. TunerStudio will quickly restart and take you back to the
Next, click on the Basic Settings tab and chose
Exhaust Gas Settings. You will need to change your EGO Sensor Type to
wideband. Burn the change to your MegaSquirt.
Your AFR Targets
Table will open underneath the More Settings tab.
With your TunerStudio project open, go to:
File > Project > Project Properties and click on the Settings tab
Under EGO O2 Sensor, chose the right option (Innovate LC-1 Default) for
your wideband in the drop down menu and click Ok. TunerStudio will
quickly restart and take you back to the main dashboard.
click on the Basic Settings tab and chose EGO Controls. You will need
to change your EGO Sensor Type to wideband or dual wideband as
appropriate for your setup. Don't forget to burn the change to your
MegaSquirt. Lastly you will need to go to the Tools menu up top and
click on Calibrate AFR Table. Chose your sensor type (Innovate LC-1
Default) in the drop down menu, and click on Write to Controller. This
is a one way flash, so don't be alarmed if your settings don't 'stick'
in this menu after you've sent them to the controller. After the write
is complete, click Close.
Your AFR Targets Table will be under
Basic setup > AFR Table 1
TunerStudio project open, go to:
File > Project > Project Properties
and click on the Settings tab
Under EGO O2 Sensor, chose the right
option (Innovate LC-1 Default) for your wideband in the drop down menu
and click Ok. TunerStudio will quickly restart and take you back to the
Next, click on the Fuel settings tab and chose
AFR/EGO Controls. You will need to change your EGO Sensor Type to
wideband. Most setups will use a single sensor with the input received
on DB37 Pin 23. If this is the case for your application, enter 1 for
Number of sensors and set your EGO Channel to Normal EGO. This is a
pink wire labeled "O2" on our harness. If you are running multiple
widebands, you will be able to set that up in this menu as well. Don't
forget to burn the change to your MegaSquirt when finished.
Lastly you will need to go to the Tools menu up top and click on
Calibrate AFR Table. If the option for Calibrate AFR Table is grayed
out, you will fist need to go to Tools > Un/Lock Sensor Calibrations,
choose Unlocked, and Burn and Close. Then you will be able to access
the Calibrate AFR Table menu under Tools. Choose your sensor type in
the drop down menu (Innovate LC-1 Default), and click on Write to
Controller. This is a one way flash, so don't be alarmed if your
settings don't 'stick' in this menu to be later viewed again after
you've sent them to the controller. After the write is complete, click
Close. If you desire, you can lock your sensor calibrations again by
visiting the Tools > Un/Lock Sensor Calibrations menu again.
AFR Targets Table will be under Fuel settings > AFR Table 1
Shipping / Customs:
Will you reduce the value of my order on the customs paperwork
or mark it as a 'gift' so I pay less
in customs duties/taxes/import fees?
|We do get asked this
there was some way to ethically avoid these taxes and fees for our international customers
but unfortunately there isn't. We must properly fill out all customs paperwork
and include a receipt with your order. We made a commitment early on in
running our business to be 100% straightforward and honest in all of our dealings,
with our customers, vendors, and even the tax-man. We hope you understand
and even find comfort in knowing that we're committed in being 100%
straightforward with you as well. We do appreciate your business and will
continue to strive to keep our prices affordable. Thanks!
|Prices do not include taxes.
Orders inside the state of Georgia are subject to a 6% sales tax. We do
not collect taxes on orders to other states or international orders;
there is currently no national US sales tax. Most international orders
are subject to tariffs or taxes upon arrival. This is collected by the
government in the country the order was shipped to, and DIYAutoTune.com
has no control over these taxes. We do not have the most up to date
information on these tax rates, either, so we recommend checking with
your local customs office for the most up to date information.
Main MegaSquirt FAQ
This is the main MegaSquirt FAQ, as well as the MegaManual. You will do
well to become one with the MegaManual. Let it flow through you. Use
Matt Cramer's MegaSquirt FAQs Some may be a bit outdated as this was
Matt's FAQ from years ago, before he worked here, still good information to keep
Innovate Motorsports FAQ Frequently Asked Questions on Innovate's
Wideband Products straight from the pros at Innovate.