|
|
Specialists
in |
|
For a Basic EFI explanation see HERE |
|
|
|
ExtraEFI.co.uk |
|
|
V2.2 and V3.0
|
This refers to the version of Main
board (Mother board) used. These can both use the MS1 or MS2 microprocessors. The V2.2 is the older style pcb, it has no VR conditioner on it, so some crank sensors can not easily be used (e.g. Ford Zetec, BMW, Vauxhall, etc). The V3.0 PCB is the later pcb and the most popular choice. This has a VR conditioner built in so the above sensors can be used easily. It also has better power supply filtering, a proto area built into it for building optional extra's that the Extra code can use, etc, etc. It has one Spark output driver as standard, but up to 6 can be added. This is the mother board I use and the one I recommend for use with the MS-Extra codes. |
|
V3.57
|
This is another style of mother board, it is electrically the same as the V3.0 pcb, but it has surface mounted components, so virtually all the components come built onto the board. BUT this board is very hard to add extra's to, e.g. a second spark output, or launch, etc. This is because it has no proto area and the surface mount components are difficult to solder to without damaging them. |
|
MicroSquirt
|
This is a very small MegaSquirt that has the ability to run 2 inputs without any modifications. BUT it can only drive two spark outputs and to do this you will lose the PWM for injectors, so you will have to use hi-impedance injectors. This currently can not use MS2-Extra code. It is really suitable for motorbikes, as space is a premium. Adding options like launch control, etc, will be very difficult to do as it has no proto area. There is also no inverted VR output on the board, so using MS1-Extra and a VR sensor is going to be difficult. Currently I don't sell these as the V3.0 offers all it can do and more in my mind. |
|
MS1
|
This is the 68H908 based microprocessor using the original B+G code that was written for MegaSquirt. It can control fuel only and uses an 8x8 VE table for fueling. This can be fitted to any pcb, V2.2, V3.0, etc (mother board) |
|
MS1-Extra
|
This is a code (firmware) that uses the same
microprocessor as the MS1 code (68H908) but adds mappable (12x12)
ignition control in various formats, e.g. wasted spark, COP, EDIS, etc.
It enlarges the fuel table (VE Table) to 12x12, it has features including
launch control, switchable maps, NOS, etc, etc. See HERE
for more on the options. This, like MS1, can be fitted to any
mother board, e.g. V2.2, V3.0, etc. |
|
MS2
|
This is a daughter board that replaces the MS1 microprocessor on the motherboard. (V2.2, V3.0, V3.57, etc) The daughter board has a HC9S12C64 based processor on it. The original B+G code on the board is known as MS2. This has some ignition control and various other features. This can be fitted to any pcb, V2.2, V3.0, etc (mother board) |
|
MS2-Extra
|
This uses the same daughter board
from the MS2 with the HC9S12C64 based processor. But it adds various
ignition controls, launch, NOS, switchable maps, etc, etc. It also has
the option of a 12x12 or a 16x16 fuel table. See HERE
for more on the options. This, like MS2, can be fitted to any mother
board, e.g. V2.2, V3.0, etc. It is a reasonably simple procedure using a laptop to install this code over the original B+G MS2 code. All the MS2 ECU's I sell have this code installed in them. See HERE for the MS-Extra Forum. |
|
Dizzy, 123, clockwork, etc
|
This is a distributor based setup. A single coil fires through the distributor to all cylinders via a rotor arm. In some setups there can be 2 distributors, each one having a seperate coil. (e.g. Lexus V8) these are dual distributor setups and need some different settings in the software to operate. See HERE for more. |
|
Wasted Spark
|
Wasted Spark is used on a lot
of modern 4 stroke engines. It is where a pair of cylinders are fired
together, one cylinder is on the compression stroke and the other on the
exhaust stroke. The 2 cylinders that are fired are the pair that move
together and are therefore opposite each other in the firing order. This
setup has multiple coils, usually 2 for a 4cy, 4 for a 8cy, etc. It does
NOT have a distributor, as the spark plugs in the cylinders are
connected directly to the coils. E.g. Rover V8 firing order = 1, 8, 4, 3, 6, 5, 7, 2 This would be 2 rotations of the crank, so 720 degrees. To fire this engine in wasted spark we would fire 1+6 together (as these are opposite in the firing order), then 90deg later we would fire 8+5(again these are opposite in the firing order), then 90deg later 4+7 then finally a further 90deg we would fire 3+2, this repeats every crank revolution. Ford 4 cylinder firing order = 1, 3, 4, 2 This would be 2 rotations of the crank, so 720 degrees. To fire this engine in wasted spark we would fire 1+4 together (as these are opposite in the firing order), then 180deg later we would fire 3+2 (again these are opposite in the firing order), this repeats every crank revolution. The cylinder that is fired on it's exhaust stroke is know as the "wasted spark" as it produces no power. The benefits are that the coil fires less often than when using a single coil and has more time to charge ready for its next spark. This is very helpful at high revs when the charge time can be very small. See HERE for more. |
|
COP
(Coil on Plug) |
A COP setup has one ignition coil per spark plug and it sits on top of the plug. This allows for an even greater charge time than a wasted spark setup would and it eliminates the need for HT leads. To drive these one at a time, in a sequential setup, you will need to have a suitable cam signal. The other, easier option is to drive them in a wasted spark format, this can be done with a suitable crank signal or cam signal. See HERE for more on COPs |
|
Speed Density
(MAP) |
The MegaSquirt ECU's have a built
in MAP (Manifold Air Pressure) sensor. This is used to measure
the engine load when in Speed Density mode. This method is nonrestrictive
(unlike a MAF sensor) and is very accurate in most setups. Unless you
have ITB's it is highly recommended to use Speed Density.
If you have a boosted engine then you almost certainly will need to use
Speed Density as it is the only way to know what pressure is in
the intake, the throttle angle would have little bearing on the amount
of air going into the cylinders. The standard MAP sensor can read
up to 21psi of boost, the MS ECU running the extra code can be used with
a 400KPa sensor (38psi) of boost. The feed to the MAP sensor must come from the engine side of the throttle plate, this is usually the same as the fuel pressure regulator's reference manifold pressure feed. A small air filter in line can remove oscillations if they occur. See HERE for more on this subject. |
|
Alpha_N
(TPS) |
An alternative method of measuring
load is to use the Throttle Position Sensor (TPS). This is not
as accurate as MAP. It can also go out of tune easily if the TPS
is moved or re-fitted, vertually any changes made to the engine will need
a re-tune, where as Speed Density is more forgiving as it uses
Volumetric Efficiency, so minor mods can be done without major re-tuning.
Alpha_N is NOT suitable for boosted engines. See Hybrid Alpha_N
for boosted Alpha_N info. Alpha_N is mainly for use when you have a radical cam that produces very little vacuum at idle or cruising, it is also for use when using ITB's, as at low RPM's a small change in throttle position can cause a massive change in the MAP pressure. See HERE for more on this subject. |
|
Hybrid Alpha_N
(TPS and MAP) |
For very rare engines it may be necessary to use both MAP and TPS. This was primarily designed for use in the Ferrari F40 where the cam is so radical it has very little vacuum at idle, so getting a good map using Speed Density was very hard. BUT as it is a boosted engine it is not possible to just use TPS (Alpha_N). To get around this the Hybrid Alpha_N mode uses TPS as the load sensor, but it adds in the MAP function in the fuelling algorithm. So the MAP sensor is connected to the intake manifold and when going into boost the fueling Pulse Width (PW) is calculated with the MAP. So the fueling PW naturally increases with boost, this means that despite the value in the fuel table, if your in boost more fuel is added. See HERE for more on this subject. |
|
ITB's
(Individual Throttle Bodies) |
Most car manufacturers produce engines with a
common plenum intake with one or maybe two throttle bodies (throttle
plates) feeding that plenum. These usually have injectors in the intake
manifold near the valves for that cylinder as this gives a better power
output at the RPMs a car engine will reach. |
|
Ford EDIS
(Electronic Distributorless Ignition System) |
This is a system that Ford used in the 90's to control ignition timing. It has a 12 pin EDIS module that is fed a crank signal from a VR sensor seeing a 36-1 wheel. The EDIS module sends out a PIP signal to the main ECU to tell it the engine speed. The ECU then sends out a SAW signal back to the EDIS module telling it what angle to fire the coils at. The EDIS module directly drives the coil pack in a wasted spark format. See HERE for more on EDIS setups. |
|
AFR
(Air:Fuel Ratio) |
The Air:Fuel Ratio (AFR) is the amount of parts of Air to one part of Fuel in the mixture. E.G. an AFR of 15.9 is 15.9 parts of Air to 1 part of fuel. An AFR of 14.7 is stoichiometric, which is the most efficient mixture for a petrol engine, so it produces the minimum emmissions. Best power is produced around 13-12.5AFR. A lower AFR means more fuel (Richer), a higher AFR means less fuel (Leaner) |