Teach me about Megasquirt Basics

I just bought an old mechanical fuel injection setup that I'm going to convert to EFI. I'm looking into several contro options, but I'm especially curious about Megasquirt, and would like opinions/suggestions etc.. from those who have used it. Pros/Cons, cost, performance, etc.. Thanks!

I have an MS1 in my 96 Miata. It was in my 93 Miata before that. It was a fun and fairly straight forward build, but I had the benifit of well documented instructions that detail every aspect of the build and install from miataturbo.net. There are also tons of maps I could choose from there and DIYAutotune. Made it pretty brainless. It would have been a lot more work if I was breaking new ground, but it sounds like your setup is pretty simple. Tuning with it is fun and simple as long as you have a Wideband. You can do it with a narrowband, just not as easily. The versatility it opens up is amazing. I had a base map from DIY that I was using NA (but it had boosted cells already). I added my turbo and went for a drive and was seeing near perfect AFR's in boost with no changes. Took 1 hour and swapped my 265cc/min injectors for some 460cc/min, changed just a few numbers in Megatune, cranked it right up and went out for another run. It's that easy.

Whatever you decide, I would buy from DIYAutotune. They have been great to deal with and the detail in their kits is unbelievable.

We have a MS-I processor on a V3 board w/a 3 bar MAP sensor (didn't need all the power and features of the MS-II proc and it was expensive when we started, not so now). We set it up on a Thick Film Ignition, aka Turd Fail I'mgonnastopworkingnow on our 2.3Turbo and it works amazing, we've actually gone past the 3-bar MAP sensor onboard, albeit just a tad, but nonetheless we've exercised the hell outta it. It can be setup to handle any ignition and fuel combo with the notable exception on the older processors not being able to do sequential, but it's great at batch, and very simple, though I think the newest one can handle sequential or is in the process of being able to. We also had the added complexity of low impedence injectors with flyback circut mods for the power. All of these extra complexities (read headaches) are covered by appendicies that have been added to the Mega-Manual over time.

If you are serious, read the manual, then read it again, then read it a couple more times and then get your kit and parts so you have an idea of what you're doing. Alot of people don't go with the little stimulator, but seriously, for $40 it's worth the investment. We burned out some components by accidentally bridging a couple connectors interntally when we were sorting an issue. Repairing would have required us to tear it down and build it up, instead with the little Stim, and Matt (MadScientist) at DIYAutoTune, we isolated the issue and had it fixed in a day. Matt's the man when it comes to troubleshooting.

I'm not going to lie, it's painful at first, and takes some serious time and effort if anything goes wrong along the way, that's why it's critical not to rush and to test everything as you go. Once you have it setup and running, and you can troubleshoot it and tune it, nothing will stop you. You'll start looking at 'horsepower' in a whole new way and gain some appreciation for 'factory tunes' that run so well, all the time, no matter what...

Thanks guys. What about cost? Do you have any idea what you have into just the Megasquirt and control components?

Look here:

http://www.diyautotune.com/

If it doesn't answer all your questions, there's millions of words written on the subject on the megasquirt forums.

bravenrace wrote: Thanks guys. What about cost? Do you have any idea what you have into just the Megasquirt and control components?

We just had a thread on this, and the answer is that it depends. If you do assembly yourself, already have all the stuff to do that sort of work, can make a harness, can find temp sensors and other little parts at the junkyard, etc you can have under $500 into it including the wideband O2.

I also recommend DIYAutotune for all your parts. Great people.

Yeah, DIYAutotune.com for parts. Build a MS1 V3.0 board, run SnS Extra code and it will do everything you need it to. I have 3 MS'ed vehicles, including my DDs.

What control components, like sensors, are required to make it work?

IIRC you'll normally need a MAP sensor or TPS (MS can handle MAP on board), water temp and air intake temp for cold engine/cold environment compensation and preferably a wideband O2 sensor for mapping.

That is if you want the MS to run the FI only.

Yeah, the MAP sensor is on the MS board. I recommend the DIYAutotune.com MapDaddy double MAP sensor so you can have Baro constantly, but you can use just the single that comes with the kit. I have narrow band O2 sensors on all 3 of my vehicles. I made the cylinder head temp and intake air temp sensors for the bike from thermistors. On the Truck, I used a Chevy air temp sensor bolted to the plenum. On the 20 valve, I just used all the OEM sensors.

I have plans (longer term) to MS my bike too. I'm thinking about getting one of those little tic-tac box wide band controllers.

Download the MegaManual and start reading.

The important thing: take your time. None of it is particularly difficult, and I've been known to compare it to a good stereo installation in terms of installation complexity. The documentation is good, tuning isn't too bad...but I HIGHLY recommend a WBo2 since it makes things so much easier.
Great device: I bought one from one of the first back in the days of the google group for a school project. So far: Briggs and Stratton 3.5, 4 Neons (stockish, 2.4 all motor, and SRT-4 variants)

I kind of have the itch to boost one of the e30's using MS....

Nathan

njansenv wrote: I kind of have the itch to boost one of the e30's using MS.... Nathan

Let me see if I can help with that.... ;)

http://www.diyautotune.com/diypnp/apps/b55/usdm-bmw-325-8792-m20b25-mt.html

http://www.e30tech.com/forum/showthread.php?p=905356

-Jerry

bravenrace, please read the megamanual:

http://www.megamanual.com/index.html

Can't get much more simple than that.

Of course DIYAutoTune is a great resource as well.

Once you have a good grasp, do some searching on the MegaSquirt forums for info on tuning with ITB's or multi-throttle body solutions since it can be a little different to tune than a more traditional single throttlebody solution.

FoundSoul wrote:

njansenv wrote: I kind of have the itch to boost one of the e30's using MS.... Nathan

Let me see if I can help with that.... ;) http://www.diyautotune.com/diypnp/apps/b55/usdm-bmw-325-8792-m20b25-mt.html http://www.e30tech.com/forum/showthread.php?p=905356 -Jerry

The power gains they got just by adding MS are eye-opening. Who'd have guessed that there was that much untapped power to be found in tuning a bimmer?

In reply to kreb:

I think part of the story with that particular car was that the owner had installed 19lb injectors, which is very common among e30 owners to allow headroom for bolt-on mods, but he hadn't tuned for them. I know we would have found power even over a 100% stock setup, maybe not quite as much though as it was getting pretty rich up top on the stock ECU.

Generally, on a bone stock 80's - 90's era car, there's 5-10% to be found just with a tune and/or with a tune and delete of the AFM. The best part of an EMS though is once the mods are poured on you can tune properly for whatever combination you put together with a nice flat AFR and timing spot on where it needs to be.

You don't have to convince me, I've seen how well documented the E30 MS stuff is (especially compared to back in the day, when I was one of the first AFAIK to try to MS both the B&G 3.5 and the NGC 2.4 SRT motor).
That said, I remember that cold start tuning was a bit of a pain....and I'd want my wife to be able to drive it without ANY sort of "modified car" quirks. We'll see. Nathan

I'll shoot you straight man.... particularly on the MS1, MS1E, and MS2 code the cold start tuning can take a little time and you get one shot a day more or less to dial it in. They all require static PW at each temp configuration, which works, but requires you to figure out what PW is needed at each temp.

That said, the MS2/Extra code doesn't require you to program the cranking PW in static PW, but rather as a percentage of REQ_FUEL which is a calculation based on your injector size and engine size. Long story short, the default settings are much closer to 'right' for more vehicles, and in most cases I've seen only need fine tuning if that. (I usually leave them as is unless I notice an issue at a certain temp).

It's good that you're asking the right questions before making the plunge. I've watched MegaSquirt's popularity explode over the past few years, but with it came the noodleheads that really didn't have an interest, were only looking for cheap hp. Would you still be considering MS if it were 2x or 3x the price?

Are you willing to solder together at least your first MS unit? And deal with a car that will take several days to become streetable, let alone smooth (can take years to accomplish)? What kind of patience do you have for problem solving?

Before considering MS, you should be in full understanding of the mechanicals of an engine, have a proficient grasp of the tuning variables and their relationships with each other (AFR, spark advance, manifold vacuum/pressure, etc), and have some basic electronics understanding.

Start making a hypothetical MS setup on paper, writing down exactly which components you will be using (brand of sensors, size/impedance of injectors, MS1-MS2, v2.2-v3 board, ignition system, etc). Now when you start into the megamanual, you will have a direction to follow and aware of which parts to concentrate on. If you are going to run HEI ignition, there's no need to bother reading through EDIS, VAST, TFI, 420A, etc instructions. If you are using GM temperature sensors, you will not need to create temp vs. resistance tables.

When I first assembled and installed my MS over 4 years ago, I knew exactly which components I was going to use, all the ones factory installed on my car. Everything I did leading up to the first start had a specific direction. All the settings had been determined well before-hand. Don't get hung up on finding someones basemap, just use the VE table generator and tune from there.

The wiring image at the top of this megamanual page is a very valuable peice. Print it off and keep referring to it while reading through the manual. It demonstrates how easy the MS setup really is when you get right down to the essentials.

Hey FoundSoul, Can you post some "works good" MS1 Extra cold start and in particular ASE settings? I actually got the Sportster to do pretty well, but I still have to start the Truck and Rolla twice, or "catch" it with throttle. They'll start cold OK (down to 0F anyway), but in that first half second they are a bit wonky. And I know exactly what you mean about only one shot a day at it.

Sure thing-- probably the easiest thing to do is hit up www.megasquirtpnp.com and download one of our basemaps we setup for the MSPNP's. The three models that are out now are MS1/Extra based and all fire up and warm up well.

In general though, I'll find what my hot cranking PW's are, and then starting working down in temp from there. It's easiest to tune the hot PW's, and you know it will need a bit more as it cools off, so I'll scale the PW up as the CLT temps drop, and then look for opportunities to fine tune it when the car is at those temps (or make opportunities). Keep in mind it's probably better to er on the lean side at first and slowly add cranking PW until it starts to catch. If the car doesn't fire up easy because there's not enough fuel, no problem, you get another chance. If you get carried away and add too much you can flood it and then need to clear the cylinders before trying again. Best to start lean and add fuel till it catches.

So... first discussing ASE and WUE from the perspective of having a hard time getting the car to start and run, and then from the perspective of tuning them properly....

Afterstart Enrichment (ASE) -- If you cranking PW's are close and the car pops off, but then immediately, or very quickly dies, your ASE is likely the problem. ASE adds extra fuel just for a few seconds, or in some cases a set number of engine cycles, after the engine starts. You can watch in the tuning software when ASE and WUE (warmup enrichments) are activated. Starting a car goes like this...

You turn the key. The ECU will show it's in cranking mode. It determines this by the fact that it sees RPM, but that RPM is below a set speed (generally about 300 rpm).

Once the engine pops off and RPM goes above that speed (300rpm in this example, it's configurable though) four things happen. Cranking mode is off, Running mode is on, ASE is activated and adding extra fuel, and WUE is activated and adding extra fuel.

ASE like I said above lasts a few seconds, maybe as long as 30 seconds. WUE lasts until the engine is up to a set temperature, usually 160*F or so. (also programmable).

If the car fires, and then dies, and your VE table is at least in the ballpark, then ASE and/or possibly WUE are likely the problem. They work together. So if the fuel commanded by the VE table is your baseline, and WUE is adding 25% because the engine is cold, and ASE is adding 15% because the engine just started, then you've got 140% of the normally commanded fuel being squirted during those first few seconds while both ASE and WUE are active. That may or may not be enough.

Usually, if the car is popping off, but then dying immediately (not even really trying to run), then you've got too little fuel, or possibly WAY the heck too much, but usually too little. Try increasing ASE in the temp range you're at and see if it improves.

If the car pops off, runs for a few seconds, you see the ASE indicator turn off and right then the car starts running rough or dies, then the WUE needs to be adjusted more than likely. That's telling you that with WUE and ASE active there's enough fuel at that temp range, but as soon as ASE turns off, there's not enough fuel even though WUE is still active, so you need more WUE.

Now... the above is just one way to help you get your car started in the first place. You will not be able to fine tune WUE or ASE until the VE table is tuned well so if you start out this way to get the car running, after you dial in your VE table you'll revisit ASE and WUE. This is not a hard thing to do unless you neglect to do it and then get frustrated that it didn't just tune itself. Most gearheads armed with a wideband o2 could tune their VE table fairly well with the software and tools provided. Ignition takes a dyno to really do right, the hardcore DIYers have some other methods, and/or just copy somebody elses map, both of which can be risky of course All that said, a quick dyno session on a steady state dyno will sort out your VE and Ignition base maps nicely and give you a very nice running motor. Costs a few bucks, but then your car runs right. Very right.

Once the VE table is tuned though tuning ASE and WE is pretty easy. You just start the car when it's cold, with a wideband, and watch it come up to temp slowly idling. As it hits each temp range that's available to tune in the Warmup Wizard, you adjust the WUE enrichment for that temp range, let it warm up to the next range and adjust it, etc. I shoot for mid 13's here usually. Then the goal with ASE is the same thing and is even easier, watch it when you start the car at different temp ranges, and adjust to target the AFR's you want to see right after it starts.

So in order.... get it started. Tune VE. Tune WUE. Tune ASE.

Generally speaking, a newer, more efficient, multiport engine with the injectors very close to the ports and atomizing nicely, will need less ASE and WUE.

A TBI engine will likely need much more ASE and WUE.

A IRTB engine will probably be somewhere in the middle of the two.

This has alot to do with the fuel having to flow through manifold with the air longer distances, and on a cold engine more of the fuel tends to fall out of the airstream, so you have to throw more fuel at it to compensate.

Thanks. I guess I just need to mess with it some more. I took the pentop out of the Truck as everything else is pretty stable. I've put 25K miles on since MS'ing it. VE is good, WUE is OK, cranking is OK. It's just that first half second of running when it dies on me if I don't work the pedal and get the RPM's up. I'm not sure if I'm at the too little or "way too much" point, and that's why I was wondering what other people where using there.

Right now, I'm waiting on a dizzy from Ken for the 'Rolla, as my VR pickup went out.

I gotta get me a wide band one of these days.

i would say that a wideband is a more useful tool then a spark plug socket.. would anyone here go without the latter?

Dr. Hess wrote: Thanks. I guess I just need to mess with it some more. I took the pentop out of the Truck as everything else is pretty stable. I've put 25K miles on since MS'ing it. VE is good, WUE is OK, cranking is OK. It's just that first half second of running when it dies on me if I don't work the pedal and get the RPM's up. I'm not sure if I'm at the too little or "way too much" point, and that's why I was wondering what other people where using there. Right now, I'm waiting on a dizzy from Ken for the 'Rolla, as my VR pickup went out. I gotta get me a wide band one of these days.

If I could give you exact settings for your car I would but it's a bit different for every car, usually you can still learn something from looking at other well tuned maps though from the trends you see there.

One other item that can play a role is the idle valve, generally you want to have an idle valve open up a good bit during cranking and right after start giving you a higher than normal idle at first, and then close down to manage a normal idle speed maybe 5 seconds after start. You'll notice OEM vehicles do this, and MS will too. You need a PWM or Stepper idle valve to do it properly, you can do it with a on/off fidle valve to some extent too.