Official megasquirt post

[stevelangford]

Starting this post since I noticed many inquires about the megasquirt system, hopefully We will learn more about this.

please post your questions, progress in building it, or tech information that may be helpful to vortex/megasquirt users

also if you already have it running please post tech tips, etc

At this moment I finished building mine and is going to be installed this weekend

website:
http://www.bgsoflex.com/megasquirt.html

you can find a zillion posts here at the yahoo group but honestly there is so much information there that creating this post here at the vortex is an attempt to filter and compile information only related to VW'S

yahoo groups:
http://autos.groups.yahoo.com/group/megasquirt/

thanks to all

[PowerDubs]

I'll kick in some info,... oh and some pics for views.

I'll try to get some more info in here once I get to work,...it *is* Fri after all!!

This is a group for everyone who is installing the Megasquirt system onto their Audi or VW to share information and ideas.

http://groups.yahoo.com/group/megaVAG

-real-time fuel calculations up to 16,000 RPM!

- instant re-programming of constants, enrichments, etc. while the vehicle is running

-supports rev limiter by fuel cutoff. RPM limit and reengage RPM can be
adjusted. Pulsewidth at fuel cutoff can be adjusted.

-on-board Manifold Absolute Pressure (MAP) sensor (Motorola MPX4115)

-MAP sensor is additionally used to obtain the barometric pressure during engine startup, in order to determine a barometric pressure correction factor.

-Air density corrections as a function of manifold air temperatue (MAT) and barometric pressure effects on VE are pre-computed as lookup tables and properly used by the ECU in the fuel calculation. Most aftermarket EFI controllers allow the user to set the air temperature correction - MagaSquirt uses the mathematical equation for air density to generate this correction, so no user intervention is required. More importantly, many aftermarket EFI controllers do not take account the effect of barometric pressure change to volumetric efficiency. This correction comes into play at high altitudes (i.e. low barometric pressures). MegaSquirt uses a lookup table to determine this correction, and is consistent with OEM systems.

-specific RPM and MAP range points are adjustable by the end user

-There is an output control signal (current sink up to 500ma) designed to drive an idle bypass solenoid (open/close solenoid, not a stepper), which allows the addition of more air at idle during warmup. The activation/deactivation temperature is set by the user.

-A relay drive circuit (up to 500 ma) is provided to control power to the fuel pump. Signal is active while the engine is cranking or running, and will deactivate 2 seconds after the last ignition event.

-option of using either SD or Alpha-N.

-Can handle throttle-body injection, can control individual port injectors

-Other people have developed and shared helpful freeware / hardware for MegaSquirt, including:

MegaTune - for tuning and datalogging MegaSquirt with a laptop

MegaTweak3000 - for refining your volumetric efficiency table from datalogged data

EasyTherm - to simplify the substitution of non-standard temperature sensors and to upload software revisions.

MS Palm - to tune and datalog with a Palm

MegaView - to provide a dedicated dash display

-The TPS sensor tells MegaSquirt what the current position of the throttle. This variable is compared to the most recent readings to determine if the throttle is opening or closing rapidly. If so, extra fuel can be added for an opening throttle to compensate for transient conditions. This functions the same as an accelerator pump in a carburetor.

-The TPS also does two other important functions. First, if the throttle is open more than a specified amount during cranking, it invokes the “flood clear” mode by reducing the injected pulsewidth to 0.3 milliseconds. Second, if the throttle is open more than 70%, exhaust gas feedback is shut off.

-options to shut off EGO correction below a specified coolant temperature or below a specified engine rpm.

-works off of signal from coil or dizzy hall sensor for ignition,..no need for special toothed wheels or magnets.

-capability to fully exploit a wide-band sensor by incorporating full time, all conditions closed loop feedback for fuelling with real-time updating of the VE table

There is now a software interface to tune/datalog MegaSquirt from Unix/Linux

Available HERE

[Trike]

gave me 199.43 whp, ran dual channels, one for water and other for injectors. ran a 6al as well. keep in mind this 199whp was with a ihi rhb5, not much bigger than a k03 this was with the wastegate unplugged. motor was a 8v 1.8L jh with g60pistons.

have any questions feel free to ask.

ps... if you read the guide.. I'm the wing diode ;-)

Modified by Trike at 6:57 AM 9-5-2003

[Trike]

just a minor correction to powerdubs

it's a 2 bar map, mpx 4250. the older units were shipped with the 4115. all newer ones shipped with the 4250. (~21psi)

[PowerDubs]

Quote, originally posted by Trike »

just a minor correction to powerdubs

Good looking out!! I just copied all that info from Lance's FAQ, so apparently he needs to update.

BTW Trike, I bought my unit preassembled new but second hand. Is there a way for me to find out which one I have? Any other changes made to the hardware or software that we should be aware of?

If I have the old MAP, will it still work for NA, or should I upgrade it?

[angusmf]

Did you buy it from Derrick in Balitmore? If so, I built that one. It's a V2, and I think was already set up for VW sensors and had the latest beta code that works great with VW ignitions. If not, just look at the board itself to find out what hardware version it is. As for firmware, you can just load it up with whatever you want, so it doesn't matter so much whats on it.

[PowerDubs]

Quote, originally posted by angusmf »

Did you buy it from Derrick in Balitmore? If so, I built that one. It's a V2, and I think was already set up for VW sensors and had the latest beta code that works great with VW ignitions.

Yes, I bought it from him. Can you explain a little more about the 'set-up' for Vw sensors, etc? I intend on running it on my 2.0 16v, and will still be using the motronic ECU for ign purposes.

Thanks

[Ricestalker]

I have my Megasquirt assembled and tested. I also buit the tester and a relay board. I have yet to wire it to my engine as I just completed the swap last week. I'm going to run 30 lb Ford injectors and an old but rebuilt T3 from a DSM. I'm in the process of trying to figure out which pins to use on the TPS connector. I found the two that control the fast idle solenoid, that leaves 5 to choose from. One I figure out which ones work I'll post the info here. I'm hoping to be able to run the stock ignition system, but I've heard that is difficult to do. I'll post here as I make progress. I'm still a long way from a running car. I still need to find an appropriate GM open element air intake temp sensor. I'm also still sourcing the parts for my fuel system. (pump regulator etc.)

Later,
Chet

[angusmf]

The coolant and air temp sensors are somewhat different on different makes (vw, toyota, ford, etc.) Megasquirt uses a table to figure out what resistance values from those sensors correspond to different temps. You use eztherm (from the files section on the yahoo group) to update the megasquirt code with the correct table for your sensors. I already loaded up both the coolant and air temp tables with values that work for the coolant sensor VW used on CIS-e, which is what you should have. This will work if you do what I did. I used a second coolant sensor for air temp. I just made a hole in the intake tube and screwed it in. The wisdom on the MS list says that works fine for naturally aspirated applications like yours. If you ever run turbo, you can grind off the brass casing from the sensor you use for air temp. This will expose the acutal sensor element inside so that it can react much faster. Then you just reinforce the leads a little with some sensor-safe RTV. Your other option is to get a GM or other air temp sensor and reload air temp table with the curve for that sensor.

[ijcameron]

Okay, this thread is pretty cool.
I built up my Megasquirt unit last weekend (and it works on the stimulator), so this weekend I'm going to get going on the installation in the car. Thanks to Angusmf, BTW for his help with this.

Some ideas:
1. Remove the cold start injector, replace it with a threaded block-off plate that will accept the GM intake air temp sensor (NAPA Item#: MPETS5100SB Price: $15.49 , pigtail for the AIT sensor NAPA item # ECHTSC300 ,Price: $ 11.49 ).
***Does anyone see any problems with that?***

2. Use the stock coolant temp sensor on the Rabbit and use Megatherm to "tune" it.

3. For the wiring from the MS to the relay, solder the cable ends while it is in the car (since the cable is just like an old printer cable, the large end pieces won't fit through any of the grommets in the fire wall).

4. Fuel supply: (this from angusmf):
First the high pressure line. This goes to the plastic nipple on the
fuel
rail if you're using one from a Digifant car. There is a hard line
coming
off the fuel filter which has a plastic line that goes to the fuel
distributor. The plastic line should be covered in the remnants of
some
rubber or steel braid. I forget which. Get down to that plastic, and
cut
it off the hard line. Replacements are easy to find, but use something
from
the junkyard if yours are nice. You'll find a barb on the end of the
hard
line. You can then run fuel injection hose (the really thick stuff
that
costs 4 bucks a foot) to the rail with hose clamps on each end. I did
it
that way so that I could use the stock filter in more-or-less the stock
position. Pure laziness. If you want to get tricky and mount yours
closer
to the pump like on an A2, you can do that too. You'd just do it the
same
as the return line. Which leads me to...

The return line is easy too. There are screw in fittings that go to
the
steel lines coming up from under the car. Same deal...just cut the
plastic
line off it, and you're left with a little fitting with a barb. Run
that
same FI hose to the exit port on the fuel pressure reg (sticks to the
end of
your Digi rail.) You can do the same with the feed line as I mentioned
above. But make sure you have a filter in there somewhere.

I also have a few questions:
1. How do I attach the accelerator cable to my Passat throttle body?
2. How do I wire the fuel pump to the relay board?

Good to see an active VW group getting on this!

[angusmf]

Few problems, Ian.

1. You won't get much flow over the sensor in that position. That's why I stuck it before the TB.

2. The coolant sensor in the rabbit is VDO. May have a totally different curve, so even with eztherm it might not work. You'd have to take readings at lots of points to get the shape of the curve. As for the other one, that connects to the O2 computer if you have one, it's on/off on an A1. So that's no good. If you can make the VDO one work, cool. Otherwise just replace the neck on your head with one that can take the CIS-e sensor.

As for your questions:

1. You can swap the linkage from your old TB to the Passat one. I did it, but it required enlarging the hole. You'll just have to try it and see. Another option is to swap cable ends. And the final choice is to try to find a cable that will work. You need a relatively long one with the correct end. Some A2s might have it.

2. No idea. I left the stock fuel pump relay in place. Works great and it's very safe (no tach signal, fuel pump no worky!)

[stevelangford]

this thread is getting excellent

I'm using the gm open element air sensor and gm coolant sensor, I figured is easier than changing the values, since I'm doing custom intercooler and coolant routing I'll be welding bungs on the pipes, (I heard standard o2 sensor bungs are the same thread, same as big spark plug anti-foulers, someone can confirm?)

the pigtails for both I got from autozone (I had to shave the little ribs on one to fit) but it clips perfect

I already have everything, fpr, fuel rail etc from a g60 and I have 32's injectors, all going into my already turboed cabriolet (jh engine)

QUESTION
what do you guys did in the resistor with the bridged wire?
what did you wire the xg1 or whatever grounding bridging that the assembly guide mentiones at the end

mine is working perfect with the stimulator / pc

[ijcameron]

Steve,
This is from the MS Megamanual:
http://members.shaw.ca/megasquirt/manual/mwire.htm

"The thread for the recommended General Motors coolant and air temperature sensors for MegaSquirt is 3/8 inch National Pipe Thread [NPT]. A 9/16 inch pilot hole is required for the tap. (Recall that pipe sizes are based on nominal inside diameters, not outside diameters as for standard National Coarse [NC] and National Fine [NF] threads...) "

Also, for the resistor with the bridged wire, I left the "legs" of the 2 resistors uncut on the underside of the board(they are side by side on the board), joined one leg from each resistor together and then soldered them together to form the bridge.

I'm not sure about the XG1 thing, if you post the step # from the megamanual, it will help me to remember what I did.



Modified by ijcameron at 12:39 PM 9-5-2003

[stevelangford]

thanks ijcameron

here's the step with the doubt

taken from assembly page

54. Now, it is choice time again, this time regarding the opto-isolator installed at U4. The LED inside of the opto-isolator is fired by a signal provided by the ignition system. The pulses existing on an ignition, especially when pulled directly off of the coil primary, can spike to very high voltages. The return path of the LED is terminated to jumper pad XG1. This return path can either go directly to the board ground (by placing a jumper from XG1 to XG2), or, the return can be brought out of one of the jumper slots on the DB-37 connector (like X11), and then grounded with a separate wire on the DB-37 connector, thus isolating the ground. Note: for the ECU to work on the stimulator, then the XG1 terminal needs to be hooked to XG2, and right now we are doing stimulator testing, so install a jumper from XG1 to XG2. Now, when you install the ECU, if you need isolation because the tach signal is resetting the ECU (for those installs tapping right off of the ignition coil (-) terminal), then you can remove this jumper and connect XG1 to X11, and ground this pin (#25 for X11) with a separate return wire. Note: if you are using a tach output from an aftermarket or many OEM setups, the tach signal is a nice +12V pulse - these will work fine with the XG1 terminal jumpered to XG2 in the install. Again: for testing right with the stimulator, hook XG1 to XG2. Later, after you install this on your vehicle, if you have reset problems, then remove this jumper and jumper XG1 to X11, and bring out a separate return ground wire.

Some installations have reported problems with low rpm “spikes”. Typically this sees the reported rpm at 1100 rpm jump to 5000+ rpm for short periods. This can make idle and off-idle tuning difficult. To fix this, try the “Dave” capacitor. This is a 0.22µf cap across the junction of D5/R10 to XG1. (See the ignition triggering section of the Tuning section of this manual for details).

[angusmf]

Leave it jumpered. Worked on mine.

---edit---

But use the 2.986 "beta" code. I got tach spikes using the straight 2.0 code. Use download.exe to load it up. That seems to be the most reliable.

---edit again---

Ian,

You shouldn't have jumpered any resistors. The trick you described is what you do with the D8 diode if I'm not mistaken.

Modified by angusmf at 2:11 PM 9-5-2003


Modified by angusmf at 2:13 PM 9-5-2003

[ijcameron]

Woops, you're right - it was "D8" I was thinking of:

49. For most installations, diode D8 (1N4733AMSCT-ND, John Zener, 5.1V, marked 1N4733) is not needed.

Steve: O2 sensors are an 18 x 1.5mm thread, same as a spark plug.


Modified by ijcameron at 2:00 PM 9-5-2003

[mrkrad]

megasquirt is cool as hell. someone should make up a batch and sell them here..

[stevelangford]

Quote, originally posted by mrkrad »

megasquirt is cool as hell. someone should make up a batch and sell them here..

yes, so far I love it, it is so versatile can't beat the price either not to mention the fun of building it

the problem selling these assembled is there is a misconception of the value of the megasquirt system, I heard things like "how come you want $200 for an assembled one if is only 120 in parts"

people don't realize that the parts are over $ 100, then wait for the stuff to arrive from 2 different sources, the hours of learning about assembling it, the hours of actual building the thing, but you have to have or buy, wires, cables, solder, soldering gun, cut the end plates or get them cnc'd, then get sensors, adapt them, get fittings, etc, by the time you finish with the project you invested over 250 dollars in stuff and at least another 250 dollars of your time, but in my opinions the concept of controlling fuelling in such an accurate and programmable way, is waaaay worth it.


Modified by stevelangford at 6:11 PM 9-5-2003

[Vento FI]

I second that!!!

[mrkrad]

and most people don't have the skills to properly build it, calibrate it, and lastly tune it. It's definitely not Plug n play yet.

I look forward to ultramegasquirt with the nernst cell support. that will make things easier. Of course cost will go up a bit but the specs so far are pretty badass.

But i would not buy a megasquirt from just anyone. I would want a unit tested (as in a car), all it takes is one bad solder to ruin your (motor) day.

poor construction of a megasquirt's would result in a bad name for them, for whoever takes up the task of making them.

So your point is valid. If i had to build them, test them, and then WARRANTY them (a must), you have to factor in costs.

You also have to factor in the fact that someone might jack it in wrong, and fry it, then you would be responsible for support and repair (Warranty).

support and warranty would be extremely costly, imo.

you can't really just sell a product without either, just wont fly for the majority of people that have no clue on how to assemble, test, tune it.

so that $120 in parts + your time + support + warranty +profit = how much?

[stevelangford]

Quote, originally posted by mrkrad »

and most people don't have the skills to properly build it, calibrate it, and lastly tune it. It's definitely not Plug n play yet. I look forward to ultramegasquirt with the nernst cell support. that will make things easier. Of course cost will go up a bit but the specs so far are pretty badass. But i would not buy a megasquirt from just anyone. I would want a unit tested (as in a car), all it takes is one bad solder to ruin your (motor) day. poor construction of a megasquirt's would result in a bad name for them, for whoever takes up the task of making them. So your point is valid. If i had to build them, test them, and then WARRANTY them (a must), you have to factor in costs. You also have to factor in the fact that someone might jack it in wrong, and fry it, then you would be responsible for support and repair (Warranty). support and warranty would be extremely costly, imo. you can't really just sell a product without either, just wont fly for the majority of people that have no clue on how to assemble, test, tune it. so that $120 in parts + your time + support + warranty +profit = how much?

yes that's what I'm talking about. keep'em coming

[Ricestalker]

Quote, originally posted by stevelangford »

yes, so far I love it, it is so versatile can't beat the price either not to mention the fun of building it the problem selling these assembled is there is a misconception of the value of the megasquirt system, I heard things like "how come you want $200 for an assembled one if is only 120 in parts" people don't realize that the parts are over $ 100, then wait for the stuff to arrive from 2 different sources, the hours of learning about assembling it, the hours of actual building the thing, but you have to have or buy, wires, cables, solder, soldering gun, cut the end plates or get them cnc'd, then get sensors, adapt them, get fittings, etc, by the time you finish with the project you invested over 250 dollars in stuff and at least another 250 dollars of your time, but in my opinions the concept of controlling fuelling in such an accurate and programmable way, is waaaay worth it. Modified by stevelangford at 6:11 PM 9-5-2003

Yeah, I said that. What you don't realize is that I said that after having built one myself. You seem to be missing my point. Let me rephrase that:

Why spend $200 on a completed MS system when for $80 less you can actually build it yourself and in the process glean an understanding of how it works, how to test it etc?

Does that make more sense.

Chet

[stevelangford]

where do you guys have the air temp sensor mounted?

[Rusto GTI]

What are you guys going to be doing for ingnition in your cars? I am so close to being sold on this route instead of digi1 but just want to make sure I will have a decent ignition system as well that can advance and retard depending on boost and other factors. Thanks

PS I know about the megaspark and all that.. i am looking more along the lines of OEM VW systems or MSD/crane types.. thanks

Rusto

[GTIMan82]

Ive just started to get my foot in the door with megasquirt, and I havent even ordered it yet! I just have to clear up a spot on my credit card Between building a head and starting college ($420 books, only 20-25 hrs a week between 2 jobs, etc...) its kinda difficult to keep the funds going!

Anyways back to your question, from what I understand if you are running CIS (I assume you are...) Swapping in a motronic brain would be the easiest way to go.
1) Its a fairly straight forward swap.
2) You can get a chip for it for a better ignition curve and a rev limiter of 8000 RPM
3)What other swap is there?

This is a very informative post! Although im focused on just getting this thing built right now, looks like a lot of my future questions have already been answered! Thanks for putting in the links with your posts!

[PowerDubs]

Quote, originally posted by CrackerX »

from what I understand if you are running CIS (I assume you are...) Swapping in a motronic brain would be the easiest way to go.

cracker, motronic would be no good for boosted, epsecially not with a chip and advanced timing curves.

Notice that he wanted- "just want to make sure I will have a decent ignition system as well that can advance and retard depending on boost"

[GTIMan82]

OH holy crap! he did say that.... Well Ill be damed... I had just gotten up and was checking my email....

Hey!! You stupid cracker..... your full of crap dude! motronic would suck for a boosted application! You cant adjust timing or anything on it! What were you thinking!

Sorry Motronic would be nice for an ez swap on a NA motor though!

[mrkrad]

you can guess timing with a motronic, but the boosted motronic's all have map sensor input. ME5.9., 7.0 and up for boosted motors all use a map sensor. the first ME5.9. derivative with boost control (dbw) and map sensing was used by the new beetle, it is quite a bit simpler than the current generation ones, but had nifty stuff never the less.

You could change the code to use a spare a/d input line to add map sensing to motronic, for the most part there's always some spare io unused since (me) motronic was a rather generic unit sold to many euro manufacturers, the idea was to build an ecu that could facilitate many cars with one design and different firmware to reduce costs.

Modified by mrkrad at 10:16 AM 9-6-2003

[stevelangford]

I'm running the standard ignition in my cabriolet and alway guessed the timing, never had any problems really up to 15 lbs of boos, but again I discovered the diagraphm inside the vacuum actuator in hte dizzy is been ruptured forever. anyway this is what is next in my list:

for $330.00 you can get this boost sensitive/adjustable msd ignition

MSD 6BTM, PN 6462
Supercharged or turbo engines will benefit from the 6BTM in more ways than one. Not only do the full energy sparks help burn the fuel mixture, it allows the driver to retard the ignition timing based on the amount of boost being produced by the supercharger. The timing is adjusted from a dash
mounted knob and can be retarded 1 - 3° per pound of boost with a maximum of 15°. There is also a built-in adjustable rev control to protect the engine from over-rev damage. Note: Same specs as the 6A except for Size:
Size: 8"Lx4"Wx2.25"H

[angusmf]

If you guys haven't already checked it out, there is code for the MS that does spark and fuel in the same box. It's called MegaSquirt'n'Spark. http://autos.groups.yahoo.com/...spark

One guy (can't remember what name he goes by on vortex) is already running it on his Rabbit witht home-made ITB setup. Since it's a full 8x8 map like the fuel, you can do pretty much anything with it, including retard under boost. Best of all, there's no extra cost.

[mrkrad]

well you do need an ignition box. i don't think the nspark actually has spark drivers, it was my understanding it used the fast-idle to send a dwell to a spark box which would fire the coil?

correct me if im wrong.

[angusmf]

VWs already have a "spark box" unless it came with points. There is usually an ignition module in the rain tray that connects to the hall sender. You feed the MSnS signal to that. It works a lot like the seperate knock-sensing spark control units found on mid-80s GTIs and GLIs. Digifant may be similar. I don't know about anything later than that since they were crank triggered.

[Jeebs]

Would this work well in an ABA 16vT using a boost controller with two presets? Im just learning about all this, so Im not sure if it would work (Im planning on using 7-10psi for cruising around and 15-17psi for AutoX and draggin').

[KrautFed]

Not VAG, but a lot of good general info:

Turbobricks.org Megasquirt info (all you need to know!)

[ijcameron]

Thanks for the Volvo link.

Quote »

where do you guys have the air temp sensor mounted?

Steve,
All of the OEM applications I saw in the junkyard yesterday have the AIT sensor either in the airbox, or in the ducting leading to the TB. ie. all of them are BEFORE the throttle body. I did see a picuture of a Megasquirt guy with a Rabbit mount his directly into the intake manifold. The guy in the Volvo link (above) did the same thing.

For my application, I"m going to mount it before the TB initially (probably use a small length of exhaust pipe to do this), and see how well it works. If that's the wrong way, someone please let me know!


Modified by ijcameron at 8:50 AM 9-7-2003