The Do It Yourself Plug-N-Play MegaSquirt
EMS
you build from a simple kit.
Application Docs:
How to jumper and configure your DIYPNP to get your car fired up on
the first try
1987-1992 BMW 325 USDM 2.5L M20B25 MT
Test Vehicle Details:
The vehicle used for drawing up these
application docs was a USDM 1987 BMW 325is 2.5L M20B25 with a manual
transmission. All
factory electronics/ignition system components are in place
and
the factory wiring harness is in perfect condition. The
only exceptiont to this are upgraded 19 LB high impedance fuel
injectors, but for the purposes of this writeup this won't
effect you. The base map we have provided (below) has been
scaled for 14lb injectors.
Other notes: Article details installing
the DIYPNP with the AFM in place, as well as deleting the AFM
for better intake airflow.
What to buy:
Required:
1-
DIYPNPB55-K Kit. This is the main
DIYPNP Kit including the Bosch Motronic style 55-pin connector
and all components, case, etc.
Optional:
1-
Tuning Cable This is
the same DB9 serial tuning cable used in other MegaSquirt
applications.
1-
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
serial port.
1-
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.
1-
PNP_IAT-A or
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.
Startup Maps
Base Configuration .msq files to help you
get your car fired up safely and quickly. Ready to
tune.
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. We have
scaled this down from the 19 LB injectors in our test car to the
stock 14 LB injectors in the Engine Constants Req_Fuel
calculator, located in the tuning software.
Once the vehicle is
started, you will need to use the MS2/Extra manuals to set the
base timing and begin to tune the vehicle! This is
critical! Do not drive an untuned vehicle!
DIYPNP Jumper Configuration
This section will cover the standard,
basic jumper configuration required to get the vehicle
running using your DIYPNP.
***
Leave D5 out of the relay #2 circuit used for
the main relay.
*** Use an 18k Ohm resistor in
series with VR+ input.
Can be in jumper wire or
proto area.
GND
14
Misc Jumpers
GND
24
On
Off
GND
OPTO GND
X
GND
BL/TH
X
IGN1
IGN2
WLED
ALED
Other Changes/Considerations
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.
12V Switched Input / Main Relay / Fuel
Pump Relay
This is the correct method to gain control over
both the Main Relay and the Fuel Pump Relay,
as well as give the DIYPNP a switched 12V power source.
(In this example we'll be using Relay
Circuit #2 for this purpose. You could use Realy Circuit
#1 with minor changes, or a proto area relay circuit if you
wanted.)
Jumper from Connector Board Pin 27 to
Relay 2 Input.
Jumper from Relay 2 Output to Connector
Board Pin 36
Leave out or remove the D5
diode of the #2 relay circuit you are using here.
Jumper from Connector Board Pin 3 to
"Fuel Pump" on the Main Board.
Jumper from Connector Board Pin 37 to
"12V" on the Main Board.
VR Sensor Input
To maintain a consistant tach signal to the
DIYPNP an 18k Ohm resistor is needed in series with
the VR+ input. There are two easy ways to accomplish this.
(1) Solder the resistor into the jumper wire from
the
Connector Board Pin 47 to "VR IN +" on the Main Board.
or
(2) Jumper into and out of the Proto Area.
Please view the Proto Area documentation
here.
Use the jumper
wire and solder between Connector Board Pin 4 and one of the outer
holes in either Proto Area. Cross over the center
section with the 18k Ohm resistor being sure to stay in the same
Proto row. Finally jumper from the opposite outer
Proto Area hole to "VR IN +" on the Main Board.
Note-- the whole goal here is to make sure
the VR Sensor + signal passes --through-- this 18K resistor
before going to the VR IN + hole on the mainboard.
TPS / Idle Air Control / Acceleration
Enrichments
This model does not have a variable TPS, rather
an on/off style. As a result the IAC type will
need to be set to "PWM Warmup" as well as the standard Accel
Enrichments (not Enhanced) used.
Until a variable TPS is added, TPS SIG from the Main Board will
need to be jumpered to Ground with a 1k Ohm resistor to prevent
the TPS signal from gradually floating higher and possibly
accidentally triggering flood clear mode.
The addition of a variable TPS will allow the use of Closed Loop
Idle Control as well as Enhanced Acceleration Enrichments as
both of these features look to the TPS signal for feedback.
3 Wire ISC Valve
These cars have a 3 wire idle speed control valve. We've
provided a driver for this on the adapter board. See
this page for details.
Sensor Calibration
Calibrate your CLT Sensor and IAT
Sensor.
Again from TunerStudio, click
'Tools > Calibrate Thermistor Tables'. Make
sure 'Coolant Temperature Sensor' is selected at the
top.
For the CLT, use the
following table with a bias resistor setting of
2490 ohms:
Temperature
F / C
Resistance In
Ohms
14 / -10
9500
68 / 20
2500
176 / 80
330
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 IAT, use the following
table with a bias resistor setting of 2490 ohms:
Temperature
F / C
Resistance In
Ohms
14 / -10
9500
68 / 20
2500
176 / 80
330
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
list.
Click 'Write to Controller'.
Once finished writing, click 'Close'.
Deleting the AFM (optional)
The DIYPNP allows you to disconnect the
Air Flow Meter. One thing to note however is when you remove the
AFM,
the stock IAT sensor comes out with it (the IAT sensor is inside
the AFM). You will therefore need to
install a GM style intake air temperature sensor in your intake.
This sensor connects to the first and forth pins on the IAT
connector, as shown in the photos below. IAT sensors have no
polarity,
so it does not matter which wire you connect to which pin.
IAT Sensor:
Simply wire a GM Open Element IAT Sensor into
your factory wiring harness at the AFM connector. You can
poke wires into the AFM connector, or you can cut and splice.
Wire one lead of the GM Sensor to the first wire at the AFM
Connector, and the other lead of the GM Sensor to the fourth
wire at the AFM Connector. There are 5 wire slots in the AFM
connector, however only 4 have terminals installed. The
two outer terminals will be the ones used.
The wires should then be folded down over the
edge of the
AFM 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.
The following dyno chart is from after fully
tuning
the engine with the AFM installed. We then removed
the AFM and added a smooth intake pipe and ran another test. 3
peak HP and 3 peak
Ft/Lb torque were gained. The DIYPNP with AFM is the solid
line and the DIYPNP without the AFM is the dotted line.
More Dyno Playtime
Dotted lines are the stock ECU. Solid
lines are the DIYPNP without the AFM. Peak gains were
about 13ft lbs and about 15whp. Under the curve though?
As much as 23ftlbs and 23whp was gained.
Turbo Time!
We were in for a surprise when this
customer returned. He has installed a T3 .63 A/R, 57 trim
turbo and was looking to make ~300 HP @ 15 PSI. Another
tuning session was in order!
We have updated our
downloadable
file with
the new MSQ scaled for 42 LB / Hr fuel injectors.
Read the Manuals, You are Responsible for your own
results!
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
begins.
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
a success.
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.