mega squirt write up, long with lots of pic's. no more maf limit for me and cheap!!

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12-01-2004, 09:50 PM

parish8

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mega squirt write up, long with lots of pic's. no more maf limit for me and cheap!!

Megasquirt is a build it yourself pcm. It is inexpensive and has many features. In it’s most basic set up it controls fueling only using speed density calculations. It also has many other features that can be activated like spark control, nitrous control, fan control, fuel pump control, water injection control, wideband a/f targeting. The list is long.

I maxed out my maf last year sometime with a mostly stock 6.0 and have been adding fuel with the PE tables in edit. It works but is such a pain in the ***. I am on a pretty tight budget and have only been kind of looking at the after market stuff. It is all expensive. A buddy of mine was talking about this mega squirt and had put it on 4 other turbo cars all ready with success so I jump right on the mega bandwagon. Thanks for all your help Scott (dieselgeek).

The most basic set up is fuel only. First thing is you have to build a mega or buy one prebuilt. I will get more into that later. Once you have the mega built and a harness built you have to put it in the car/truck. The mega is a small metal case that you mount anywhere inside the car that will fit, it is best to put it somewhere you can get to it to take it back out incase you want to add features to it later. Then you plug in the harness and run the wires where they need to go. For fuel only there are 7 things you have to hook up. It took us about 4 hours to do a nice job with it on my truck. We installed new sensors for the intake air and the coolant rather than tap off the factory stuff.

1. One wire to a coolant temp sensor. You also have to ground the other side of the sensor out under the hood.
2. One wire to a intake air temp sensor. You also have to ground the other side of the sensor out under the hood.
3. Throttle pos sensor. For this one you just tap off the factory throttle position sensor.
4. 2 injector wires, you take one injector wire to 4 injectors, ground side only. Then the other injector wire to the other 4 injectors, ground side only.
5. Tach signal wire.
6. Power and ground wires.
7. Vacume line from intake to the mega.

http://www.neufamily.org/images/megapics/DSCN2137.JPG
http://www.neufamily.org/images/megapics/dscn2135.JPG
http://www.neufamily.org/images/megapics/DSCN2136.JPG

It was real easy to hook it all up. Now getting it to fire the first time was a little tricky. No one had any files for a ls1 so we were on our own. You tell mega what you size motor you are running and what size injectors you have an it helps with a couple of numbers but for the most part you have to come up with something that works. Luckily for you we did this all ready and you could start with our numbers and I bet it would fire about many motors. Here is the first screens you have to fill out to get it to start.

http://www.neufamily.org/images/mega...aconstants.jpg
http://www.neufamily.org/images/mega...nrichments.jpg

Before you try to fire it be sure to have a fire extinguisher on hand!! We didn’t get any backfires or anything but it took us about ½ hour of trying different things and cranking to get it to start and run.

Now for tuning! The fun part. It is soooo easy to tune with this thing. All corrections are on the fly (real time) . Change a number and see what it does, that easy. I have a wideband 02 sensor so it is easy. While it is warming up you adjust the warm up enrichments to where you want the 02 to read. You have to do the warm up over a couple of days. Then comes the VE table. You just look at what cell it is running in and then adjust the corners of the cell up or down to get the o2 where you want it.

http://www.neufamily.org/images/megapics/megave.jpg

We adjusted the cell we were idling in first then slowly revved it up into different cells and adjusted them. Then put it in drive and see where it goes and adjust, then rev it a little and adjust. At some point you have to go adjust the acceleration enrichments but we didn’t do much with them till after we got the VE table close.

Once we got it running and the ve’s set at idle we went for a spin. I putted around and did different things to get into more ve cells as Scott (dieselgeek) adjusted the ve’s we slowly got into higher kpa and rpm numbers as he clicked away. It didn’t take any more than an hour to completely fill in that map starting from scratch. We were making wot runs within an hour and the fueling was where we wanted it to be. So far we have tuned up to 6000rpm and 11psi. Only pump gas so far.

The wot stuff is super easy. The warm up is easy but you have to do it on a new day with the motor cold. The accel enrichment has been a little harder but still easy. We just drove around for a couple of hours trying different things and seeing where it seemed to need more or less fuel, we basically adjusted the accelerator pump till it drove nice.

We ran into a few snags along the way. First thing was getting my laptop to communicate with mega, I always have this problem with edit/efilive or anything it seems, not having a real serial port seems to cause conflicts. We also had a little trouble getting a good tach signal. The mega pulls down the factory signal too far for anything to work, we hooked in a “pull up circuit” and all is well now. The pull up circuit for this set up was nothing more than a 12v ign power running thru a 380ohm resistor hooked right up to the tack lead. Other small problems was not having the latest firmware and software. Loading the latest firmware and soft ware. The last bug we had to work thru appears to be a programming thing, thru test driving we found a spot where the injectors would just shot off for a sec at WOT, not a good thing. We figured out what conditions caused this. We had to rescale the ve table to not go over 100%, some kind of math error in the software that they now know about and will fix.

We are headed to the dyno on Saturday to really push my STOCK motor, just for fun. There may be more to add in the tuning information after we crank it up but so far it is running awesome and has been super easy to tune. The real time programming really speeds things up.

Long post huh, I should be done but I’m not . Couple of things left to talk about. How to build the thing and other features.

If you’re a build it yourself kind of guy the mega is really cheap. I am talking something like $240 for all the parts. I need Scott to post up on actual costs because he built mine. I would estimate including the 2 new sensors, all wiring and the mega there is less than $300 in parts. This includes the extra circuits to run low z injectors even. There are people selling these things on the internet prebuilt and Scott is thinking about getting set up to sell prebuilt ones as well. Right now he has sold several to people on the turbo probe boards and they are working out great. The hard part seems to be in the details, working thru the bugs like we did. If Scott sell prebuilt units they will all ready have the harness all made up with the “pull up circuit” wired in. probably send them out with my basic tune and the exact firmware and software I am running. That right there will save a lot of hassles. There is a good network of people out there running the mega and they all seem to want to help each other. Building something yourself and having it work it pretty cool. Here is the link to the mega web site >> http://www.bgsoflex.com/megasquirt.html . I have found it kind of hard to find the information you need. All the info is there but not always easy to find.

Here are more pic’s of my mega.

http://www.neufamily.org/images/megapics/DSCN2139.JPG
http://www.neufamily.org/images/megapics/DSCN2140.JPG
http://www.neufamily.org/images/megapics/dscn2138.JPG
http://www.neufamily.org/images/megapics/DSCN2141.JPG

Other features. The basic mega pictured above needs a little more hardware if you want to add features. There is something called a fly back board that we don’t have in there yet and that lets us run the low z injectors, Scott has tried this on one car so far and it is running great. Some other features like fan control or fuel pump control are pretty simple, you need to add something like 3 components. So far we have added in fan control and it works exactly as advertised.

There is bad *** nitrous control set up that we just tried to hook up but it isn’t working exactly as we expected, we need to spend a little more time on that one. Right now it sends out a signal like a WOT switch and window switch which right there would save a few bucks but it is suppose to be able to add fuel with the injectors making for a pretty trick dry set up. I listed many of the features up top and we have not tested or wired up any of there other than the fans and to try the nitrous. We are also going to try and hook up the ignition control portion too. I have edit so it isn’t really needed but timing adjustments on the fly would be so nice. To hook up the ignition control you use a couple of parts off of a ford set up called EDIS. You have to adapt a crank wheel to the balancer somehow and a vr sensor, also a moduel under the hood that goes to the coil packs. From what I understand this adds about $140 worth of parts if you buy them all new. Many people goto the junk yard for them, I guess they are very stout and last forever.

Last edited by parish8; 12-01-2004 at 11:17 PM.

mega squirt write up, long with lots of pic's. no more maf limit for me and cheap!!

mega squirt write up, long with lots of pic's. no more maf limit for me and cheap!!

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