I've decided on Megasquirt

Yesterday I recieved the 2 barrel manifold in the mail thanks to Lafester. I just orderd some aluminum stock today through Metal Supermarkets. I'm having them cut me a piece of 1"x4.75"x5.5" 6160. Once recieved I will be using my drill and a dremel to make an adapter plate which will allow me to bolt up the 4.3L GM TBI to my new manifold. After that I will work out where I need to hook up the temp sensor. I need one for the dash gauge and one for the Megasquirt unit. I'll send pics of the adapter plate when completed. I've spent alot of time reading the megasquirt manual. It is complicated...but doable. Not just a bolt on upgrade.

 

LOL!!!! I KNOW what you mean!!! LOL!!!!

 

I had the friend over yesterday that has the megasquirt system, I have the controller in the front seat of my truck to tinker with for a week or so. I have found out a huge amount by playing with it and asking questions. The megasquirt controller does not care if the engine is an oddfire or not. Timing of the fuel injection is irrelavent for the controller or the engine, the throttlebody works just like a carb, it only electronically meters the fuel thru the O2, temp, rpm and various other things. The injector supplies fuel to the intake, the cylinder still draws the fuel into the chamber just like a carb. Heck from my understanding of the manual, if you tell the controller it is on an oddfire motor you can even use the oddfire tach signal to drive the injector pulse thru the controller instead of using a evenly spaced crank trigger. I will post more as I read and find out more, but as of right now this is looking a whole lot easier than anything Holley or the factory's ever built.

 

i will definitely be following your progress on this!

 

Found out today that the megasquirt system use's rpm averaging in oddfire mode to account for the oddfire of the ignition pulse sent to the computer to fire the injectors, this is why the unit will run an oddfire motor, nobody else's setup is that controllable by the user. the manual on this thing is long but by the time i'm finished I should know just about everything about this unit.
I just pulled 20 hours of overtime this week so I think I'm going to order the control board and stimulator kits this next week and start soldering them together in the next month or so.

 

I just ordered mine today...I got the V2.2 MS and stim, relay board and a wiring kit and one extra db37 fitting. I also just got my block of aluminum so I can work on the adapter for the tbi to manfold. The more I read about megasquirt the greater I think it is!

Update they were out of the v2.2 and I decided to get the upgraded v3.0 which is much beefier. Glad I went that route. The V3.0 includes the flyback circuit in it so you can use low impedence injectors without having to buy the extra flyback board.

 

i think i will just send the check back and you can make me one of those adapter plates

i didn't know the manifold was going for such a good cause. can't wait for the very detailed and illustrated write up

thanks, chris

 

If you're comfortable with electronics assembly, it sounds like a great system. As HudsonHawk noted, it has no "limp home" circuit like the the GM TBI, so I would carry a spare CPU board. I'll be interested to see how it works out with the odd fire engines.

 

I read thru this post twice with no mention of limp home mode. If the CPU board goes out on a GM TBI there is no limp home mode as there is nothing to fire the injectors (ask me how I know). You really need to go to the megasquirt site and read a little, there are dozens of guys there that are running this setup on oddfire v6's and Harley engines (oddfire also) along with several v4's, most of which are oddfire.

 

It was in a previous post - maybe in HudsonHawk's intro post? IIRC the GM system does have a "limp home" mode, but I'm sure you're right about a CPU failure. Sorry - should have thought twice about that. The limp home would be in case of a sensor failure (or?) - the Megasquirt does not have the "limp home" feature, so you have to be able to fix more things in the field.

All I know about the oddfire EFI is that it's been discussed plenty here. Seemed like the concensus was "too difficult" or else required the Holley analog system(?). I'd simply be interested to see if it becomes the new hot setup for ECJ5 V6s... I'm a big fan of EFI generally, though I've dealt with a lot of (crude, fiddly, inefficient) arburetors over the years.

 

Tim is correct. There is no "Limp home" mode for the ECU in case of a sensor failure. In case of ECU failure, the MS is cheap enough that you can carry a spare in your tool chest. Here is a complete list of sensor's that Megasquirt uses:

CLT - water temp
IAT - temp of air coming into the motor
MAP - manifold air preassure
TPS - throttle position sensor (Megasquirt can be configured to run on MAP only)
TACH - engine RPM
O2 - Oxygen feedback (for closed loop mode but not required)

Unlike most modern cars that is a very small list of things to break. At the bare minimum you only need 4 inputs into the system to make it run. It is completely customizable so can be made to run almost any internal combustion engine. (Not quite capable of of coil on plug yet or Direct Injection Diesel engines.)

I have had mine running for about a year. I just recently upgraded to the MS-II processor so I could use the IAC built into the GM TBI to help with warmup. I am very happy with its performance and I only have a rough tune to the VE table. (I just have never had time to fine tune the map. I use Closed Loop Mode so the O2 sensor keeps me from running rich or lean.)

 

Tim from what I have read now on the megasquirt site, the reason the Holley and others are difficult to use on an oddfire is the fact that you really have very little control of the features that allow it to be adaptable. The megasquirt will even run a lawnmower engine, the controller has an oddfire ignition tune in the processor control. Obviously I haven't used this yet but I have done enough reading and talked to several other guys that have used it now and they say all say that there are 4x the controls on the megasquirt than on anything that Holley or the factory make, I mean Holley basically tells you theres is setup for a I4, I6 or v8, megasquirt says 1-12 cylinders odd or evenfire and can even be adapted to a 2 stroke engine.

 

I keep reading that Holly is the only other kit that you can use. Affordable Fuel Injection now makes a kit specifically for the odd fire 225. Just thought you all would like to know.

 

Yea but its not affordable.
Oh and the Holley kit is usable but it seems to have a few issues that Megasquirt accounts for.

 

I hear you about the not affordable. That is why I bought Steve's EFI setup off of his odd fire here for much cheaper that building one.

 

Just finished my intake adapter. GM TBI to a stock 225 manifold.
Recieved my MS V3.0 on Wed. Will start to put it together as time allows.