The Do It Yourself Plug-N-Play MegaSquirt EMS
you build from a simple kit.
How to jumper and configure your DIYPNP to get your car fired up on
the first try
1999-2000 Mazda Miata USDM 1.8L BP MT
Test Vehicle Details:
The vehicle used for drawing up these
application docs was a USDM 1999 Mazda Miata 1.8L with a manual transmission. All
factory electronics/ignition system components are in place and
the factory wiring harness is in perfect condition.
MAF in place
DIYPNP Sequential module installed
Jackson Racing supercharger installed
330cc fuel injectors installed
GM IAT sensor used
What to buy:
DIYPNPN76-K Kit. This is the main
DIYPNP Kit including the Nippon Denso style 76-pin connector
and all components, case, etc.
Tuning Cable This is
the same DB9 serial tuning cable used in other MegaSquirt
USB Adapter This is
a DB9 serial to USB adapter. The adapter is needed when
the laptop or PC you are using does not have a built in DB9
StimPower This is a power supply
that is normally sold to power a stimulator, but another use is
it can be plugged directly into the DIYPNP mainboard to power
the ECU directly, allowing you to load the basemaps and do
limited testing on the ECU prior to installing the ECU in your
vehicle. It is particularly nice to be able to flash the
firmware and load your configuration on the bench instead of in
the vehicle, and allows for less risk of damaging something on
the vehicle due to incorrect settings.
PNP_IAT-S AFM/MAF Delete kit. This
is a simple kit with an IAT sensor, wire pigtail, crimp pins to
poke into the AFM Connector to run the signal back to the ECU,
and a steel or aluminum bung (hence the -A and -S in the part
numbers). Perfect for getting rid of a restrictive AFM/MAF
with your DIYPNP install.
What tools you'll need:
Soldering Iron, Solder, maybe some
desoldering braid in case you make a mistake. Small
phillips screwdriver. That's about it.
Base Configuration .msq files to help you
get your car fired up safely and quickly. Ready to
We're including these maps prior to
showing you how to jumper your DIYPNP up. There's a reason
for that. The base ignition settings contained in these
maps should be loaded on your DIYPNP before you power your car
up (with the key) with the DIYPNP installed. This is to
prevent damage to your ignition system in case the default
settings are not correct for your vehicle. Note that you can
power up the DIYPNP off the vehicle on a power supply connected
to the power jack next to the DB15 connector.
So here's our
recommendation-- After you complete basic assembly, Power
up your DIYPNP one of two ways. Either plug a
Stimulator Power Supply
into the front panel of the box (the easiest way),
or, start the Jumper Section below, but only connect the power
and ground wires to start with. That way you can plug the
DIYPNP into your factory wiring harness and safely power it from
your car. The third option, if you've fully assembled and
jumpered your DIYPNP already, is to unplug your coils from their
power connectors before plugging the DIYPNP into your factory
harness and powering it from there.
Then and only then,
you can flash the firmware on your DIYPNP to the MS2/Extra
firmware if you haven't already, and then load the startup map
provided to help you get your vehicle started.
ALED to Connectorboard 4Q - VICS control *
European models with immobilizer use 4P.
Sequential Injection Wiring (by firing order,
not cylinder order) --------------------------- INJ output #1 -
output #2 - 4Y INJ output #3 - 4Z INJ output #4 -
This section will cover changes that need to be made
to the DIYPNP that go beyond the standard I/O jumpering, such as intake
valve butterfly activation, on/off VVT activation, or other
customizations to address the specific needs of a vehicle.
In the Jumper Notes above we've included a
pair of jumpers for radiator fan activation using the 'Relay 1' circuit.
You'll notice we suggested using PA0 on the mainboard to drive
the fan, and run the output from 'Relay 1' over to 1R on the
ConnectorBoard to drive the fan relay. You can configure
the fan activation in TunerStudio from the 'Extended > Output Ports
Settings' Menu. More information on configuration can be
found in the
MS2/Extra Documentation here.
In the Jumper Notes above we've included jumpers for
A/C clutch and fan activation using the 'Input 1' circuit.
The Input for the AC system comes in from the A/C switch on
ConnectorBoard pin 1P. The output of the "Input 1" circuit
gets jumpered to both 1S and 1I on the ConnectorBoard.
These two pins will activate the A/C compressor clutch relay and
the A/C condensor fan relay. You will need to leave R14
out of this circuit or cut out R14 if you installed it.
In the Jumper Notes above we've included jumpers for the VICS variable
induction system. The VICS actuator should have vacuum at
idle and changes state at 5000 RPM. We have used ALED as
the output to control the VICS system at Connectorboard 4Q with RPM as a single
output condition, a threshold of > 5000, a hysterisys of 300,
"power on" set to 0, and "trigger value" set to 1. This
all means that the output will activate at 5000 RPMs, won't turn
back off until 4700 RPMs, is off when the MS is powred and the
engine is started, and is activated when triggered. If
your VICS appears to be opposite and has no vacuum to the
actuator after the DIYPNP install at idle, you may need to swap
the "power on" and "trigger value" numbers.
Sequential or Batch Injection
You have a choice here. You can go with
the conventional batch fire of the fuel injectors or you could
go full 4 cylinder sequential injection using the DIYPNP
Click here as well for the full sequential documentation.
The injector outputs are numbered as they appear in the firing order
when using the sequential injection mode. 1-3-4-2.
Injector one remains the first injector, while injector two
is actually cylinder three. Injector three is from
cylinder four and injector four is from cylinder two.
If you choose batch mode continue to wire the injectors as you normally would
by following the jumper configuration above.
Alternator Voltage Regulation
The voltage regulator for the 1999 Miata
alternator is built into the factory engine computer. We
have successfully used this circuit below to regulate the
alternator's voltage. This circuit has been passed around on
Miata forums for a while and we believe it was originally
designed by Jason Cuadra. We've modified it to fit the DIYPNP
Click on the picture for a larger view.
This circuit requires a switched 12V input, ground, and connection of the circuit's output
to the "Field" terminal. The Proto Area under the
MicroSquirt Module is a very convenient place to build this
circuit. Switched 12V can be taken from one of the three
12V terminals on the DIYPNP mainboard, ground can be used from
the terminal just beside the Proto Area, and the "Field" output
can be jumpered to Connectorboard terminal 1O.
This vehicle does have a variable TPS.
You should calibrate it properly from TunerStudio in the
'Tools' menu. Choose 'Calibrate TPS'.
Make sure the engine is off, and
the key is on.
With your foot off of the throttle,
click the 'Closed Throttle ADC Count - GET CURRENT'
Put the throttle to the floor.
With your foot fully depressing the throttle, click the
'Full Throttle ADC Count - GET CURRENT' Button.
Calibrate your CLT Sensor and IAT
Again from TunerStudio, click
'Tools > Calibrate Thermistor Tables'. Make
sure 'Coolant Temperature Sensor' is selected at the
For the CLT, use the
following table with a bias resistor setting of
F / C
14 / -10
68 / 20
176 / 80
Enter these values, and click
'Write to Controller'.
Now you'll do the same for the
IAT. Select 'Intake Temperature Sensor' at the
top in the drop down box.
(NOTE - If you are removing
your MAF/AFM as a part of the DIYPNP installation
process, do not recalibrate your IAT Sensor now)
For the stock IAT, use the following
table with a bias resistor setting of 2490 ohms:
F / C
-4 / -20
104 / 40
176 / 80
For the GM IAT sensor, use the following
table with a bias resistor setting of 2490 ohms:
Enter these values, and click
'Write to Controller'. Now click Close to Exit.
Finally, you should calibrate your O2
Sensor to the ECU. To do this, click 'Tools >
Calibrate AFR Table'.
Choose your O2 Sensor from the
list. Choose Narrowband for the stock O2
Sensor. Or select your wideband and the proper
configuration of said wideband from the drop-down
Click 'Write to Controller'.
Once finished writing, click 'Close'.
Deleting the MAF
The DIYPNP allows you to disconnect the Mass
Air Flow meter. When you remove the MAF, you will need to
install a GM style intake air temperature sensor in your intake.
The IAT sensor on NB Miatas has a separate plug with two wires, as shown in the photos below. IAT sensors have no polarity,
so it does not matter which wire you connect to which pin.
Simply wire a GM Open Element IAT Sensor into
your factory wiring harness at the IAT connector. You can
poke wires into the IAT connector, or you can cut and splice.
There are only two leads to this IAT connector. It does
not matter which way you connect them as the IAT sensor does not
have a specific polarity.
The wires should then be folded down over the edge of the
IAT connector, and the
whole assembly firmly and cleanly wrapped in high quality electrical tape sealing it up. 3M makes
some good stuff that can handle the temps found in engine bays-- read the specs.
Mounting the DIYPNP
The DIYPNP actually fits quite well in the
stock ECU location between the brake and clutch pedals. We
have reused the lower bracket only and secured the DIYPNP with
zip ties to the lower ECU bracket at the bottom side of the
unit. At the top of the DIYPNP we have again used zip ties
to hold the DIYPNP steady against the clutch pedal bracket.
Read the Manuals, You are Responsible for your own
This Application Doc is intended to assist
you in your DIYPNP DIY EFI Installation. We've done a fair
amount of research, and actually tested on a similar vehicle to
help ensure we can provide the most accurate information
possible to make your installation go as smoothly as possible.
That said, there are certain things you could do incorrectly, or
certain things you could change up, that could cause you to run
into issues. Our tech support department will be glad to
assist you working through any issues you might have, please
contact us and give us that opportunity and we should be able to
work things out for you.
Startup Maps included/attached to this
Application Doc is intended only to help you get your engine
started so that you can properly tune your engine. The map
will be setup properly for a stock vehicle matching the
year/make/model/trim in the 'Test Vehicle Details' section at
the top of this page. If you have made any changes to your
wiring, your ignition system, or other related components, this
map may not be ideal for your vehicle. You will then need
to check and confirm the appropriate settings and properly
configure your DIYPNP EMS for your altered vehicle. Some
maps offered may be more completely tuned that others, some may
be just setup enough to get the car to fire up and idle with a
little help from the throttle. That's when the tuning
In short-- We've provided you with the
building blocks for an incredible EMS. You are however
responsible for the implementation and your own successes or
lack thereof, but rest assured that we're here for you and we're
going to do everything in our power to make sure your project is
For more information on configuring and
tuning your DIYPNP EMS, and for information on adding and tuning
custom MS2/Extra features, read up at
http://www.msextra.com/ms2extra/. In fact, everyone
implementing this system should read that manual from front to
back if you really want to harness the power of the DIYPNP EMS.