[Megasquirt] General topic?

[[L'e$kro]]

Here is a draft on the FAQ. I'll add more and more to it during my spare time.

What is Megasquirt?

MegaSquirt is general purpose aftermarket electronic fuel injection (EFI) controller designed to be used with a wide range of spark-ignition internal combustion engines (i.e., not diesel engines.) MegaSquirt was designed by Bruce Bowling and Al Grippo in 2001.

Compared to other aftermarket ECUs, the approach is more DIY, as you can buy them in kits to assemble yourself. The firmwares are made collaboratively.

What are the differences between versions?
Here it's a bit confusing for most, so hang on:
There are 3 generations of Megasquirt ECUs, which are defined by the version of their processor (CPU): MS1, MS2 and MS3
In the original kits sold as DIY kits or assembled kits, there are also several revisions of the main board (a.k.a PCB), where you attach the CPU: PCB versions are V1.01 V2.2 V3.0 and V3.57
As of now, only board revisions 3.0 and 3.57 are still sold, the main difference being that 3.57 is surface mounted components, only sold preassembled.
Some ignorant or dishonest sellers might advertise a MS1 CPU on a version 3 PCB as a MS3, so in doubt, please ask here!

Here is a chart comparing the CPU versions and their capabilities http://www.msextra.com/feature-xref.html

All 3 versions can run fuel and spark on an MX5, so don't discard the older MS1 and MS2 which are up for the job for less money.
Basically, the more recent the CPU is, the more input and output ports there are, so you can run more features at the same time.
The MS1 is unlikely to receive any further development, most of the new features are added to the newer MS3, with some features back ported to MS2

Now that we've explained the basics of the original kits, here are some products that are interesting for the mx5, as they allow retaining the oem loom with its connector.

MX5-specific options

The MegasquirtPNP, aka MSPNP
As the name says it's plug and play, or almost.

MSPNP Website
The product page on DIYautorune.com

The Gen1 (that I'm running myself) is based on a MS1 Processor. No longer sold, was replaced by the gen2, based on MS2.

Install is easy, There is a fuse to remove, then swap the ECU and run a vacuum line to the manifold. The MAnifold Pressure (MAP) sensor is onboard, on the ECU.. It can run with the AFM in place, but if you want to remove the AFM, you'll have to install an Intake Air Temperature Sensor (IAT) and use a piece of pipe where the AFM was.


The DIYPNP
http://www.diyautotune.com/diypnp/
That's an unassembled kit. It's a cheaper option than the MSPNP, but you'll have to figure how to wire the jumpers inside to mach the MX5's pinout.
The kit you want is the one with the Nippondenso connector: http://www.diyautotune.com/catalog/diyp ... p-384.html


Ok, so what else do I need?

-A cable for tuning. As laptops with COM (aka RS232, DB9, Serial) ports are getting scarce nowadays, you will need a cable with a Serial to USB chip in it. I've tried many of the very cheap eBay ones, they simply don't work, or don't work consistently and will cause you headaches! If you order from DIYAutotune, I strongly suggest you get the cable from them as well, at least it works consistently. You can use a bluetooth to serial adapter as well, it works well for tuning, but AFAIK you won't be able to update the firmware with it.

Optional (especially if you get your car tuned by a shop)
-A Wideband/AFR kit. That's an exhaust oxygen sensor that will tell you how rich or lean you are running. A gauge is not mandatory but is nice to have, as you probably won't drive around all the time with your laptop or Android tablet.
-Knock sensor/detcan. you can make a mechanical stethoscope with some rubber pipe (google "detcan"), or alternatively, you can buy a cheap mono amp, or build one from a Maplin kit, and use any knock sensor from the scrapyard, some shielded cable, and use headphones to hear detonations/knock. Handy to have for tuning. Costs a few euros, and it's another feedback you get from your engine
-Exhaust Gas Temperature (EGT) sensor. Also known as k-type/thermocouple sensor. Sensors are very cheap, and you need a small electronic interface to turn the signal into a 0-5v. The overall cost of this is cheap, and it's handy to have for tuning as well.. I wouldn't keep the sensor plugged in pre-turbo as if the sensor fails it will take the turbo with it. I keep mine plugged in the downpipe, and add 100ºC to the reading.

How do I tune my car?
To be added later

[[L'e$kro]]

(Place holder)

[Steve]

Done.
I went for the "ECU talk" option as theres a few of us with LINK ECU's still too

[[L'e$kro]]

Good man Steve!
Thanks for that
Nico

[Randy]

I have a few links I can post. Did a bit of research before I committed to buying one.
Will post later.

[leamyj]

Hi all, haven't posted here for some time now. Some of you will know that I turbo'd my mk1(1.6) this year (2015) and I'm running a bipes ACU setup to adjust the timing. I'm really happy that so far I've had no teething troubles.However, I was warned before doing this that I would catch the bug for constant upgrade and I'm afraid I may have been infected!!
My question is the age old one..is it possible to upgrade to a megasquirt without having to sell a kidney?? My head is telling me to upgrade other stuff first..brakes/suspension/etc , but my heart is aching to increase HP via the ecu..... Someone please tell me to cop on to myself and listen to my head
Comments, good or bad, welcome!!

PS Happy Christmas everyone

John

[sidewaysreilly]

All I seem to see are questions over how to do this and how to do that with the Megasquirt. Surely there are better options out there.

[[L'e$kro]]

Yep there are questions from people who arent professional tuners but are willing to learn something. It's a different market than other ECUs, which are targetted at people who don't work on their cars themselves.
Professional tuners prefer installing plug and play ECUs than messing with ecus/looms built by the owner, as troubleshooting wiring faults can take time while they should simply be tuning the car.
Thats why DIYautotune sells the MS3 pro for the professional market.
For our "old" 4 cylinders running batch fuel and ignition, pretty much anything can run them.
But we are lucky enough to have the plug and play solution for the Mx5, the MSPNP. No need for hacking the loom, and easy installation.. And no soldering required
Nico

Edit: John, the DIYPNP is slightly cheaper than the MSPNP but you have to assemble it yourself...
Nico

[andrew]

Good to hear you went turbo John, be careful going cheap on a megasquirt, they can be a ball ache if you have problems with initial startup and idle. I'd recommend buying a reverent made ecu as he will give you a custom made ecu for your car and turbo build. He will also help u out if you have any problems. If u do build your own or buy a second hand ecu, you will do well to find anyone billing to help solve problems.

[sidewaysreilly]

Batch fuel and ignition?????

[[L'e$kro]]

Batch fuel and ignition?????

I meant paired injectors (referred to as batch mode, as opposed to sequential mode) and paired coils. "Wasted spark" would be more appropriate term for ignition than "batch". My point was that you need only 2 outputs for ignition and 2 outputs for injection, not as complex to run as lets say, a V12 with coil on plugs individually triggered and sequential injection, that would require 24 CPU outputs in total.
Nico


EDIT: added some content to the original post..

[sidewaysreilly]

Why would you waste fuel by firing 2 Injectors at the same time?

[[L'e$kro]]

You don't really waste that much fuel when squirting on a closed valve, it has nowhere to go. Most cars until late 90s worked this way. The main issue from a performance point if you is that you fire minimum twice per cycle, instead of once, so injectors are twice as much in their "opening" or "closing" phase. If you have massive injectors, and you spray only a couple of ms at idle, the opening or closing delays become almost as much as your injection duration, which leads to an imprecise fuelling. In sequential mode you inject once, so you can control fuelling better even with big injectors. I have 850cc/min in another car, sequentially fired, and no idle issue. In batch mode that would be all over the place..

[sidewaysreilly]

I scoped my injector pulse at idle, just to try the scope, and it seems to pulse the on time to minimise the fuel delivered at idle.