Megasquirting my 383

[John Milmont]

Hi guys,

This is my first forte into DFI and I have been doing a lot of reading. I have a map for VE, spark and AFR from a very similar engine and i think will get me going; but my problem is all of the other settings. For instance, I have no idea what to set my "Injector open time" to, or how to configure the idle control steps. Somehow i don't think everyone is taking out their IAC motors and guessing/checking the number of steps they have. I'm sure my late 80's TPI setup has been done countless times and someone must have some defaults. Most of the information I've been finding pertains to the theory and what the settings do. But, this doesn't help when I have no baseline for my given hardware.

It would be really great if someone could point me in the right direction to find this information.

Thanks,
John

 

[Francis Lucas]

I was considering going Megasquirt on one of my projects but went with a re-tune on a factory ECM instead so I can't offer advice but there are several really good forums where the MS gurus hang out. Try: www.MSefi.com • Index page

or here is site that lists others: MegaSquirt Forums

Francis

 

[Jim Cowden]

Injector open time is usually in milli seconds MS.
This will vary depending on fuel pressure and choice of injector.

Std FP of say 35psi and a STD injector maybe any were from 1.5 to 3 MS.
If you have higher fuel pressure then this will drop ,lower pressure this will go up , if you have larger injectors it go down ,smaller it will go up.

Set the pressure before you start as it will change everything if you want to change it later.

Steps is relating to its position, it is a stepper motor (steps).
It gets steped in or out to to open or close the air bypass to adjust the idle.

I have no idea about the mega squirt unit.
Throw 10 deg timing in for a start in the idle area.
Keep adding fuel until it starts

once it starts if it wont hold idle when hot increase idle steps till it does.

Most programs will ask for things like inj type,high or low impedance.
crank senser type, hall effect or reluctor, is it tuned on tps or manifold pressure ect ect ect you need to read the book to see what mega squirt requires in those areas.

The maps are 3d meaning at 3000rpm at 1/2 throttle it will have say 50% load and will require x fuel x ign.

at 3000rpm at full throttle it will require more fuel and x ignition.

You need some way of measuring a/f ratio and detonation.

Good luck it will keep you busy for some time.

I presume you have been on the mega squirt site.

Jim

 

[Jack Houpe]

John I use electromotive programable EFI on most all of my cars, not being familiar with megasquirt but other than terminology I would think the basics to be same. Electromotive has a wizard that will point you in a starting direction and then the fun begins fine tuning it. If you go to there website you can download the program or you can email me and I will email it to you.

 

[John Milmont]

Jack, I sent you an email.

Jim,
I have knock sensors and a wideband o2 - hardware is all taken care of. What I need though, is settings or defaults for that hardware. When I see something like the attached images (the values pictured are just gibberish), I have no idea what to put in. Now, what these setting do is explained well. But, that doesn't educate me on what reasonable values for these things are.

Thanks,
John

 

[Jack Houpe]

John, just from my experience turn off the knock and the closed loop control via the ego sensor, all these functions are great once you have your engine running but can be a nightmare if you don't have the initial parameters correct, and any acceleration enrichments till you get it running on the basic program. Use very little cold start enrichment and add just a little at a time till you find it starting and running. You may have to offset the the injector pulse width on the bottom if your max pulse width is high. Email if you have any questions, I hope you got the program I sent.

 

[Mikael]

What each of those variables mean and how to calculate reasonable starting values is covered extensively in the Mega Manual. If you expect to install, program, and tune your own EFI system, it's advisable that you be very familiar with all of the parameters involved.

Also check out the previously linked Megasquirt forums. You're much more likely to find good Megasquirt-specific answers there than you are here.

 

[Jack Houpe]

Mikael, you spell your name different, you fly a flag from a different country than the USA and you say your in Iowa and this is your first post with a link attached to it.

Doesn't look good to me guys.

 

[David]

It is the valid link to the manual.
MegaManual Index

 

[Jack Houpe]

My apogy.