Need fuel management advice: megasquirt

[mycarsucks]

Ok, I'm taking a serious look at megasquirt ( http://www.bgsoflex.com/megasquirt.html )to control my buick. I have an 85, and will soon be running out of injector. Unfortunately, to get new injectors there are a lot of things I would need to do. (This is the right way to do things in my opinion vs an 85 chip for older maf and such)

86/87 ECM conversion -- 60 (ecm, wiring, mat)
Extender chip -- 120
Trans Plus -- 250
Scantool upgrade -- 160
used injectors -- 200
maf -- 120

So, for an injector upgrade I'm looking at approximately 900 dollars. (keep in mind they are approximate prices)

It looks like I could get a megasquirt system a bit cheaper with a possibly increase in functionality

megasquirt -- 250 (going high for conservatism)
used injectors -- 200

This comes to around 450 and would probably be 75-100 cheaper in real life.

Pros I can see with megasquirt:

No chip reliance
I can change injectors at will
price
Very good scan tool
No More Maf Issues
great potential for a propane/alky controller as well
Tunability

Cons I can see with megasquirt:

I don't know how timing will work out, or if its even possible
Much less knowledge/support


Anyone tried this? Mostly I would like to see if there is a way to work with ignition, and what the rest of you think.

 

[mycarsucks]

Forgot to mention that I'm a computer science major, and this kind of thing is right up my alley.

 

[turbo buicks]

currently MS isnt made to control ign. but ive heard of a MS Ultra coming soon being able to handle ign. id say you could maybe use the stk ecm for ign, just plug MS in for fuel control and use the stk ecm for ign control.

 

[jastrckl]

there are current version of MS that do spark.

http://www.megasquirt.info/Ignition.htm

UMS will do all kinds of crazy stuff, including closed loop wbo2, 12 channels availble for spark or ignition, etc etc.

http://www.megasquirt.info/UMS.htm

I'm thinking you may want to look into a maxeffort mafless also. problem is you'd still want the 86/87 ecm & scantool. maf is out though.

 

[bruce]

Being electronic don't forget about carrying a spare, and once you drop the MAF you'll really need to.

The GN code and ecm is a VERY well thought out devise. Lots of people that haven't bothered to figure it out rant about the aftermarkets being so much better, when in fact they benefits are just being alledgedly easier to program. And that's changed in the newest generation of aftermarkets since they've realized it takes a certain level of sophistication, to give a car good manners.

The one size fits all code that folks want to use, is the stumbling block, IMB. If you want to get into writting your own code, the by all means a MS. If your just wanting better management the just look at other GM ecms. ie the 1227749, used in the Syclones is MAP, uses a much faster ALDL, and can be found in junkyards.

ABTW, self diagnostics doesn't sound like much until you have a problem, and they can save hours of effort on tracking down a problem.

 

[bruce]

Originally posted by mycarsucks

And one other thing, they mounted the MAP sensor in the ecm, so you have to route a vac source to it. And the line acts as a capacitor, ie mechanical filtering of the signal. So at a min use some small copper tubing, for the vac line.

BTW, I like Bruce's design, and if I knew enough about code would probably buy one. Making the code truely Turbo specifc, is a wonderful thing. I have my own code running in a GN ecm, and it's been worth every minute of the almost 2 years I have invested in it getting it right.

 

[mycarsucks]

Thanks for all the info guys. If I did this there would be a good chance I would relocate the Map sensor. I too don't trust a long line

bruce: Where did you get your info on coding the current gm ecm that sounds interesting. Probably not the route I will take, but still sounds very interesting.


jastrckl: I know about the emgasquirt spark options, but I'm not sure If I can get them to interface with the buick hardware. I'm hoping that you know a way?

If I did just run fuel with MS, and just ignition with the stock ECM would I be asking for trouble?

 

[1987BuickGrandN]

its all too much trouble, you'll have too much downtime in messing with alternate options, IMO

 

[BJM]

I am surprised a computer science person would go aftermarket. The complete documented code is available on GNTTYPE. I spent the winter reading the spreadsheet over there. You won't get past the interface of an aftermarket piece since its proprietary, if you wind up finding a shortcoming, you are stuck. With the GM code you can re write it if you are good enough at it.

The point about spare electronics is a good one. If I blow up my ECM, I can buy spares for $50.

The aftermarket stuff is designed to entice non-code literate types into the tuning game, people who know cars but are not really software types. GM put a lot of man years of devlopment into these ECMs and they have a lot of sophisticated features. Look through the data tables alone in the spreadsheet and you will find it hard to believe an aftermarket box could compete.

If you really want in car programmability you can buy one of several PROM emulators for your tuning sessions. For software I have been using TunerPro. It is free and you can comfigure it yourself.

EPROM erasers are cheap and are being thrown away these days. EPROMS are ~2-4 bucks each and of course are reprogrammable. Programmers are ~$200 max and are general purpose, not just dedicated to your car.

 

[wagon]

I have been looking into the Mega Squirt myself. Mostly just out of curiosity(so far).
Two points.
One: The web site points out the distance that the MAP source has to go. It says that most sytems have the MAP sensor on the firewall, and if you are mounting the box on the other side of the firewall, then it wouldn't be traveling that much further. Measure the distance that most people use for their MAP for say FAST or DFI, then the distance you would have to have for the Mega Squirt. I bet it wouldn't be that far off.
Two: The currently available MS doesn't use a stepper motor for the IAC. Just an on/off, so it won't control ours. Probably only matters when the engine is cold.

 

[bruce]

Originally posted by mycarsucks
Thanks for all the info guys. If I did this there would be a good chance I would relocate the Map sensor. I too don't trust a long line
bruce: Where did you get your info on coding the current gm ecm that sounds interesting. Probably not the route I will take, but still sounds very interesting.

In the one I looked at the MAP didn't appear to be weather resistant. It's a matter of signal dampening that's the problem.

There is a way to read the ROM part of the code. Then that was written with the normal PROM coding, so that it what used to be in the ROM, is now incorporated into a 27128 PROM. Once it was to the stage of being source code, the we've been able to do anything we want. ie, it now a MAP system.

In the DIY-EFI archives are the how to's for reading the ROM, and the rest just takes having someone really coce savy with the time and interest to actually do it.

Another option is using a P4 ecm like the Syclones did, where all the code is on the PROM. Then just comment that, and taylor it to suit your needs. And there is freeware scanners, and data loggers for that one. That's be the most eloquent solution in my book.

 

[bruce]

Originally posted by 1987BuickGrandN
its all too much trouble, you'll have too much downtime in messing with alternate options, IMO

Keep it plug and play and you can mess with the options as your feel like.

I have my car set up for using a Gen VI, stock GN ECM, modified ECM, ME MAFless, and for a 1227749. Takes less then 30 secs to swap from ecm to another. If I want to run 2 bar instead of 3, and a minute to swap plugs at the MAP..

There's a tremendous amount of learning that can go with playing with options like this.

 

[mycarsucks]

I actually do have a prom reader/programmer and all that fancy stuff. Maybe I will look at doing things that way. However, it still looks like its going to be very expensive to just upgrade injectors. To be honest with all of you, the cost of this simple upgrade is the only thing keeping me from progressing with this car.

BJM: Are you sure you are looking at megasquirt when you are talking proprietary? It has completely open code and hardware specs. So open that you actually build it all yourself.

Downtime isn't much of an issue. This car is really just a toy. So, in that case, I might do a bit of looking and see what I can do to get the GM ECM to work. I guess I'll have a special hotair maf chip burned in the process.....

 

[bruce]

Originally posted by wagon
I have been looking into the Mega Squirt myself. Mostly just out of curiosity(so far).
Two points.
One: The web site points out the distance that the MAP source has to go. It says that most sytems have the MAP sensor on the firewall, and if you are mounting the box on the other side of the firewall, then it wouldn't be traveling that much further. Measure the distance that most people use for their MAP for say FAST or DFI, then the distance you would have to have for the Mega Squirt. I bet it wouldn't be that far off.
Two: The currently available MS doesn't use a stepper motor for the IAC. Just an on/off, so it won't control ours. Probably only matters when the engine is cold.

Might look closer at some of the MAP routings people are using. Some are very well thought thru. The MAP lines can add a temendous amount of mechanical filtering to the signal, and yes it can/does matter.

If you're going to remove the glove box, then yes you can get close but routing and working on things get nightmarish.

Depending on what you're doing and engine combo, the IAC can be a good friend. Over run throttle snaps, burn out stalls, all can be well managed with the IAC.

 

[mycarsucks]

Man, you are fast bruce. I actually plan on using one of the MAP sensors from a TTA. I asuume that model is weather proof? And I still agree with you, the length and material of the tube matters. I think the comment the designers made about length not mattering was with an N/A motor. I doubt the same rules apply to elastic tubing under boost.

I forgot to mention that MS would allow me to run other TB units instead of the stocker. I think I could probably get the IAC working stepper style.

 

[BJM]

BJM: Are you sure you are looking at megasquirt when you are talking proprietary? It has completely open code and hardware specs. So open that you actually build it all yourself.

Sorry, I should have been more clear. Most systems are GUI driven things. Megasquirt is quite different.

Are there any key hardware features that the stock ECM is missing that Megasquirt does have. I am sorting of ignoring the MAF vs MAP debate. I see that it is quite fast and is a true 16 bit device.

 

[bruce]

Originally posted by mycarsucks
Man, you are fast bruce. I actually plan on using one of the MAP sensors from a TTA. I asuume that model is weather proof? And I still agree with you, the length and material of the tube matters. I think the comment the designers made about length not mattering was with an N/A motor. I doubt the same rules apply to elastic tubing under boost.

I forgot to mention that MS would allow me to run other TB units instead of the stocker. I think I could probably get the IAC working stepper style.

Is the output as linear as the one their using?.

N/A or S/C doesn't matter, it's critical in either, if you want the best possible, then you have to get real picky. And the better the data logging you have the more apparent all this becomes.
In just a quick throttle snap off idle I saw a difference of almost 10 K/Pa in changing the MAP plumbing, and that's enough to effect the MAP part of the AE. Not to mention the difference in where the ecm was looking in the VE table.

 

[bruce]

Originally posted by BJM

Are there any key hardware features that the stock ECM is missing that Megasquirt does have. I am sorting of ignoring the MAF vs MAP debate. I see that it is quite fast and is a true 16 bit device.

You need alot of processing power when you run the entire code, instead of in loops.

Time in PE enrichment.
TPS enable for a secondary timing table.
All sorts of TCC stuff.
In the GN code almost 1/3 of it is for the IAC, and the MS doesn't even do IAC.

Does MS, even do PE?.

Never mind what you can cut and paste into the code when you go ROMless.

It definetly takes a certain level of sophistication to get things civilized.

 

[mycarsucks]

I can think of a few things, but keep in mind I'm absolutely no expert.

MS can be modified to use a WBO2 sensor, and EGT. I think this is a standard feature in the next version (Ultra Mega Squirt)

There is a dual fuel table feature that allows the ECM to control complex progressive alky or propane injection.

Has "ScanMaster" interface that I believe isnt limited to lower speeds like aldl. Also has really cool logging/tuning software that I just can't seem to find screenshots for right now.

Doesn't use chips/can use low or high imp injectors

Like said above though, there may be issues with IAC and Ignition.

If I find any more, or if I find out I'm inccorrect I'll repost.

 

[mycarsucks]

You are fast again bruce
This is from the MS Features page"

A nice feature on the MegaSquirt controller not found on other systems are three indicator LEDs which reflect the current operating mode of the controller. The first LED pulses whenever there is an injection event, and the glow duration follows the actual injector pulsewidth. The second LED is active whenever the ECU is in a warmup enrichment state (i.e not at 100%). The third LED indicates an acceleration enrichment, and is active during the entire duration of the event. Extremely useful, especially during installation and debug. Flashing lights also look "cool", particularly when you show off your controller to others

I assume that the acceleration enrichment would be equivalent to PE. I could be mistaken