MS1 microprocessor

MS2 Daughter Board

MS3 Daughter Board

Overview: Most people like to have the latest and fastest stuff that's available. This is great, but there's nothing what-so-ever wrong with the MS1-Extra ECU when compared to the faster processors of MS2 and MS3. Indeed the MS1-Extra code was written in assembly language, this makes for a very efficient code when compared to the C language used in the standard B+G MS2. Certain time sensitive parts of the MS2 code were re-written in assembly for MS2-Extra to make it more efficient. But when you concider that at 8000rpm it takes 7.5mSec for a piston to do one complete stroke, this is very slow compared to the time it takes the MS1-Extra ECU to process the fueling calculations for the engine. The MS2-Extra and MS3 ECUs can control stepper motor idle valves, where as the MS1-Extra can only control 2 or 3 wired idle valves. But the MS2-Extra ECU has less outputs than the MS1 and MS3 so some of the features can't be used with the Stepper controller on an MS2 anyhow, as those outputs are needed for some features. See HERE for a chart of feature comparisons.

MS1-Extra: The MS1 ECU has been used successfully on everything from Ferrari's to 2CV's, 27Litre V12 Rolls Royce Merlin engines with 24 spark plugs to one cylinder lawnmower engines, so it has a proven track record. Indeed the MS2-Extra can run all those too. The MS2-Extra is a little more expensive, around £50 more than an equivalent MS1-Extra ECU, so that's also a consideration. As far as backup is concerned there are probably the same amount of people out there running MS1-Extra as MS2-Extra and backup on both codes is easy from either my own help and support pages or the MSExtra.com forums.
In most cases the MS1-Extra ECU is perfect for the job, e.g. a Ford Zetec, the MS1 ECU can be bought from me with 2 spark drivers for the coil packs, I set it up ready to read the 36-1 crank wheel and it will drive the Ford idle valve fine. Something like an RV8 is also fine on MS1, it would need the idle valve changing to a bosch unit, as MS1 can't control the stepper that the RV8 has as standard on the hotwire setups. Then an MS2 could also run the RV8 and you'd get control of the standard idle valve. If your changing an engine to throttle bodies you probably won't have an idle valve, so an MS1 will be fine with that, as would an MS2.

MS2-Extra: The main advantage of the MS2-Extra ECU is that it can be used on a lot more vehicles without fitting a different crank wheel (e.g. Renault RENIX, Rover K series, etc). So MS2-Extra is more versatile if you want to go for a setup that's a little more plug-n-play. It also has a faster processor and more RAM, so that allows it to be more accurate, e.g. timing resolution of 0.1deg with MS2-Extra, where as with MS1-Extra it is 0.3deg. The fueling control in MS2-Extra also has improved resolution, in theory it is capable of 0.67uSecs where as MS1 is 100uSecs. This means you can control large injectors better at idle with MS2-Extra. As you can see, MS1-Extra is still very impressive as far as accuracy is concerned, but MS2-Extra is clearly a step ahead in the resolution steaks.
If your going to be boosting your engine and using HUGE injectors, then MS2 is the way to go, as it has better control over the fueling, in that the injectors can be controlled that much finer for better fuel adjustments, so idle and cruise speeds are easier to tune. Also having a 16x16 fuel table that the MS2-Extra code offers helps a lot when tuning a boosted engine!
Now, MS2 can also control 4 injector channels, so it can run a 4cy in full sequential fuel, as well as a 6 and 8cy in semi-sequential fuel.

MS3: This is the new boy on the block and due to that the code will be going under a lot of changes in the first few months, so it will really be suited more for the users who are familiar with MS ECU's and who arent worried about testing Beta codes, etc.
Once it's stable, this processor will give you all that the MS2-Extra code has, plus SD card datalogging (SD card slot is built into the ECU), USB comms (MS1 and MS2 need's a convertor thats around £20) and it can have another board plugged into it (MS3X) that will give it lots and lots of inputs and outputs as well as 8 injector drivers and 8 low powered ignition drivers. For more on the MS3X board see HERE.
The MS3 also has a larger spark map than MS1 and MS2, 16 x 16 rather than 12 x 12.

DIYPnP: This is pretty specific to your vehicle, in that if your application doesn't have one of the available plugs you can't use it. So if you have a plug thats suitable then you can take advantage of the DIYPnP ECU. It has a MicroSquirt, running MS2-Extra, at the heart of it. With the ability to use 2 trigger inputs as standard, it can do sequential COP up to a 4cylinder, if you have the correct Cam and Crank signals. The DIYPnP also means you dont have to cut into your existing wiring loom to make it work. Most users will find that they will want to remove the AFM they're OEM used, this would mean some mods to the loom to add an air temperature sensor. This is not upgradeable to MS3.

RV8PnP: Again, this is specific to your engine loom having the correct plug (in this case the Lucas 14CUX) and it means you don't have to cut into your loom to fit it. But unlike the DIYPnP, the RV8PnP has a normal (what I concider to be a normal ECU) MS2 running inside it, not the microsquirt module, built using a V3.0 board and is therefore upgradeable to MS3 like the general ECU's I sell.

Conclusion: Most people find that an MS2 ECU is a bit smoother running than an MS1 as it has a few better tools for acceleration enrichment and has a finer control over the injectors, I have to agree here, the MS1 is a fantastic ECU for the money, but the MS2 is just a step or so further forward. I also believe the MS2 is easier to tune than MS1, as the lastest tuning software, Tuner Studio, has been written around it.
Now there's also sequential fueling for MS2-Extra, semi-sequential for up to 12cy engines and fully sequential for up to 4cy engines, this allows the MS2 to compete against ECUs that are 5 to 10 times the price of an MS2-Extra. The MS2 has a trim table for fuel on each injector output (up to 4) allowing very high accuracy on most engines.
Alternatively the MS3 has all the MS2, plus it has the ability to datalog straight to an SD card (built in slot) and it can communicate via the USB output without an adaptor.
If you go for an MS3 with an MS3X board, it can control up to a V8 fully sequentially fuel / spark (COPs) and it has a trim table for every cylinder fuel and ignition up to 8 channels The MS3X will give you Launch, Switchable maps, NOS outputs, spare ADC's, etc, so it's a case of weighing up if you need all those options for the cost.

So you see, there's no definitive answer as to which one you should choose really. All have their own merits, for the money the MS1-Extra ECU can't be beaten, it is simply the best ECU you can buy for the money, it out rivals many ECU's that cost several times as much, but then the same can be said for the MS2-Extra ECU. All the ECU's also have excellent technical manuals that I have helped to compile. Well I would think they are excellent :o) and a superb forum for help (www.msextra.com)
The main thing to remember, is that all the MS1 and MS2 ECUs (except DIYPnP) can be upgraded to MS2 or MS3 if you feel the need, so even if you decide later that you wanted an MS2 rather than an MS1 or an MS3 rather than either of the others, then it can be modified at a small cost, and you have another model.

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