MegaSquirt

B Frye · 02-07-2003, 04:41 PM

What ever happened to the Mega Squirt project?
Did it do an impersonation of the Spruce Goose (flew for a few yards then got stored)? Is it dead? In limbo?

mike mueller · 02-07-2003, 05:17 PM

There are at least 30+ cars running it...heck it could be 2 or 3 times that figure.....

Two 914's that I know of are running the Megasquirt
....one in San Rafel and mine
(mine sorta of, I'm rebuilding the engine right now and have a stock 2.0 with the D-Jet in the car for another month or so)

mike95125 · 02-07-2003, 08:40 PM

As soon as Mike sends me the board I can start on my corvair powered 914 running MS FI. Its not dead, its just that some times things take a while due to funds, and resources.
By the way, thanks again Mike

3D914 · 3D914's Garage

mike mueller,

When you say there are 30+ cars running the Mega Squirt, you don't mean 30+ 914s do you?

If so, where are all these guys/gals? I'm so tired of pissing time away on this D-Jet system, I'm ready to spend the money for a CIS system I was reading about. There seems to be a lot more interest in this Mega Squirt system though. I suspect its because of the programmability.

TIA - desparate!

Mark Henry · 03-03-2003, 05:27 AM

The SDS PE fuel injection system costs a lot more then the DIY mega squirt, but I’m trying to get a group buy going. About the price of a new MPS.

http://shoptalkforums.com/bbs/NonCGI/Forum23/HTML/000668.html

Dave at Pelican Parts · Dave at Pelican Parts's Garage

30+ cars (and trucks, and etc.) running MS. Only a couple of 914s, though. And one or two other Type IV-powered vehicles (Buses).

I keep hoping Mueller will get his dialed in correctly, but he keeps changing the motor.

Now he's got a couple of different header systems he's putting on there... Depending on which one he sells.

--DD

mike95125 · 03-03-2003, 03:27 PM

Maybe I'll beat Mike to it!

douglas robbins · 03-05-2003, 11:00 AM

For those of us not on the edge of fuel delivery technology, what exactly is Mega Squirt? How does it differ from carbs, mechanical FI or, EFI? What are supposed to be its advantages over carbs, MFI, and EFI?

Douglas

mike mueller · 03-05-2003, 11:27 AM

Megasquirt is a Do-it-yourself Electronic Fuel Injection Computer.
As of now it is only for fuel, but it does a kick-@ss job at doing it.

For most cars running the stock FI, there is nothing wrong with keeping the OEM ECU, but for some applications, the OEM ECU cannot be easily tweaked to compensate for modified engines.

I put the MS on a bone-stock 2.0 since I didn't care for the D-Jet system too much (the MS was easier for me to understand than trying to learn the D-Jet)

For the price, the MS cannot be beat if you compare it to the higher end FI systems like Electromotive and SDS, plus a few others. It is a kit, so one must build the ECU and hook everything up....it's not rocket science, but mistakes can be made...I made a few while installing mine, but it was my fault, not that of the MS.

Megasquirt Home Page

Dave at Pelican Parts · Dave at Pelican Parts's Garage

The joy is that the thing is completely programmable. You plug it in to a Windows computer (most people use a laptop, otherwise the cords get unwieldy

) and you can change the fuel maps and such on the fly.

You can even buy a kit to re-program the ECU chip, not just the data values stored in ROM. But a total re-program is generally not needed.

--DD

pbanders · pbanders's Garage

The MS is similar to the D-Jetronic in that it is a speed-density system. Unlike air volume or air mass flow systems (flap or heated wire), it requires a map of the volumetric efficiency of the motor to be programmed into the unit, so that mixture correction as a function of pumping efficiency is accomplished.

Getting the map right is part of the problem with programming these types of systems. In D-Jet, the map is hard-wired into the daughter card of the ECU in the form of a set of four or five waveform generators. For a rough estimate of what the curve should look like, refer to my web pages, where there are plots of injection time vs. engine speed for various load conditions. It should be possible to extract the VE curve from this data, to a first estimate.

As for other functions, you will have to start with the defaults and tweek: cold start, cold-cold start, hot start, acceleration, overrun, etc. To do all this tweeking correctly, you will likely require some chassis dyno time. Dyno time also might be required to assure that you will pass emissions.

You need to make certain that the sensors you're using will work with your motor. The throttle sensor may be a hard one to get a compatable unit.

Lastly, if you have a stock motor, don't expect significant performance improvements over D-Jet or L-Jet. Both of these systems were optimized for the mechanical limitations of the motors they were designed for and you're unlikely to find much performance was left on the table. For modified motors, that's another story.

mike mueller · 03-05-2003, 02:33 PM

Here is a bad picture of my new TPS installed on the bracket for the stock TPS on my 2.0

Pictured next to the stock air temp sensor is a new GM unit, I could have used the stock air temp sensor, but I didn't know if mine was good and the GM unit cost like 10 bucks.

Mike

Jim Smolka · 03-05-2003, 06:20 PM

Being a controls guy, I am very interested in the MS system.

However, I am very interested how the analog (0-12VDC) signals are processed. There is the head temp sensor, air temp sensor, MPS signal, and TPS. How does the MS handle the actual analog signals going into it??? Could an analog signal from a MAF be incorporated also???

Thanks in advance.

Tonyakavw · 03-05-2003, 06:43 PM

Looks like the processor they use has analog to digital converters. On the schematic, there's a simple pi filter presumably to filter ignition and other sources of noise and clamping diode on the input to the A/D to prevent negative voltage spikes from showing up.

-Tony AKAVW

mike95125 · 03-05-2003, 10:06 PM

You can do a logic conversion to use a MAF. The MS also has a connection for an O2 sensor, which gives more feed back than the stock D, L-jet when installed. This is not a requirement though. I intend to use the O2 sensor though, as well as adapting a Ford EDIS 32-1 ignition system.
Hey Mike, nice pic!

Peter_Hinkle · 03-05-2003, 10:22 PM

I am in the process of building mine right now. When i get my 2.2 finished, it might just be turbo charged and if i turbo it, it will ge the MS. That should be REALLY fun! peter

pbanders · pbanders's Garage

Quote:

Originally posted by mike mueller

Here is a bad picture of my new TPS installed on the bracket for the stock TPS on my 2.0

So, it looks like you took your D-Jet TPS and used the metal plate in it as a base for the new TPS. Good idea!

What did you do for a CHT?

JWest · 03-06-2003, 09:09 AM

The TPS is pretty easy because the MS is only looking for a transient, not an exact voltage. Anything that gives a variable voltage (resistance) as the throttle moves will work, which is most cars these days. Mikes solution looks great.

For my Jag, I found a Volvo TPS that looks identical (and uses the same connector) to the original Jag L-jet TPS, but it has a variable resistor instead of the switches inside.

IIRC Mike used the factory CHT for temp. It's not too important to have it right, because once the engine is warm it has no effect. The warm-up parameters are fully adjustable in software, so as long as the resistance is going in the right direction as the engine heats, it will work OK. The temp numbers might show funny on the laptop, but you can insert a different file in the MS chip and correct for this. This is not so easy, but can be done by following the explicit directions on the MS Yahoo site.

mike mueller · 03-06-2003, 09:33 AM

Brad,

I did use the stock 914 CHT....mostly because YOU did the homework for me

Suprisingly, the GM sensor reads the same resistance at normal operating temperature as the 914 CHT (300ohms I think????)
So for my cold start fuel enrichment, I just kept the default 180° temperature knowing that the CHT was really reading 300° or whatever it is.

I would have used the stock 914 Air Temp Sensor, but I couldn't find the information about it that I wanted to at the time. I do want to use the stock 914 ATS, so I guess I just have to find a known good one or new one to test.

Now that I think of it, I didn't use the stock 914 Air Temp Sensor since I thought I read that they are NLA....is this correct?

3D914 · 3D914's Garage

Mike,

The 914 Air Temp Sensor shuold still be available. I bought one at BAPS a few months back. Don't recall the part number though.

Also, thanks to you (and the other Mike) for doing all this work.

Regards,