ntomsheck

iTrader: (1)

I recently purchased the Megasquirt II unassembled kit and am in the process of assembling it.

In the megamanual, there is a line (under step #65) which reads "it allows you to eliminate a separate ignition module, such as a GM HEI 7 or 8 pin module, and run the coil directly from MegaSquirt."

But I can't find any more information on it.

http://www.diyautotune.com/tech_arti...lock_v8_v6.htm lists completely different information than the GM HEI module page does, as far as jumpers:
http://www.megamanual.com/ms2/GM_7pinHEI.htm

Has anyone used the high current driver to run the coil directly? Did you still have to get hall sensor signal from the ignition module? Or did you wire it directly to the pickup coil in the dizzy? Is it worth it? Far down the road, I'm planning on EDIS, but for now I just want to get it running without too many variables.

Six_Shooter

iTrader: (2)

If you just want to get it running, keep the HEI module, it's a simple interface and only a couple jumpers are needed to make it work (along with a resistor IIRC).

I know some people have had issues triggering the coil directly from their MS, but there are a variety of reasons for that, from poor workmanship, to improper components for the application to just poor circuit design.

The simplest get it up and running step would be to keep the HEI module. Instructions on hardware and software set-up are in the Mega Manual.

ntomsheck

iTrader: (1)

Good call, thanks!

Colt

As long as you are not running crazy compression ratios or high RPM's, HEI is fine. I run a MSII with the 8-pin and it works great.

There is quite a conversion process to not run an HEI system on a SBC, there is kits out there to do this but its most likely not needed for your setup. Its also a expensive.

project89

iTrader: (1)

the only reason to really get rid of it is if u want to run a crank trigger setup , and at that point u may as well just go coil on plug setup, or ford edis

ntomsheck

iTrader: (1)

That's what I was figuring, but the megamanual seemed to rattle it off so casually. I didn't know if it was a common thing. My thought process was that if it were easy, it would eliminate an extra module (and potential failure point). The ECU is now built, I'm wiring for standard HEI as suggested.

Colt

I have always felt the mega manual leaves much to be desired and is not organized well. I think i have also seen contradictory information concerning some of the ignition settings (going high, going low). There is also incomplete information on modules.

willexoIX

Yep. I found a number of typos and errors in the megamanual and have emailed both Matt and James about it.

vortec350s10

It does work well without using the HEI module, that's how I'm running ignition on my old Honda CRX. Megasquirt reads the pickup coil in the distributor (VR input) and the high current coil driver fires the coil.

On my Iroc, I've been running ignition with a MSD 6AL-2 programmable box which has worked great, however that also triggers off the pickup coil and the timing advances with rpm even though the advance mechanisms are locked out. I think it might be because of slop in the timing chain, distributor, cam walk, etc. it will advance about 5 degrees from idle to 4,000 rpm. Now that I'm going mega squirt in the Iroc, I've installed a 36-1 crank trigger wheel to hopefully stabilize the timing.

ntomsheck

iTrader: (1)

That's what I wanted to know, thanks! Did you have any issues with getting a clean signal back to the megasquirt? I know it's AC, and I've read it's a weaker signal. My harness came with the sheilded twisted pair that I'm currently using for the HEI module, so if I don't go EDIS, I'll be going this route and I can reuse the wire.

vortec350s10

I did notice the R52 and R56 pots are tricky to get set right but once you get them dialed in you're good.
I ran a shielded wire on mine too and I found out if it runs too close with the coil wire it will loose sync when you rev it up above idle.

Colt

vortec, if you are seeing timing increase with the timing fixed, you might have the Ignition Capture backwards. If its set to rising edge right now, try setting it to falling edge. When this is set wrong, your timing will increase with rpm like you are seeing.

vortec350s10

That very well could the case but if I remember correctly I don't think the MSD box worked with the pickup coil polarity reversed. Or maybe I never tried it. Ha I don't remember. But I believe it's typical for the timing to actually retard itself with cam walk. Does that sound right?

Colt

I'm not sure how it would manifest itself, but i doubt you would see a linear gain or loss in timing. My guess would be you would see a movement of a few degrees in timing when transitioning on or off the gas and then the timing would just stay there.

There is a couple things you can check to see if there's walk, but your going to have to get dirty. You can check the back of the engine behind the cam if its moving that way, or you can see if its hitting the timing cover if its going the other way. You can also check the wear pattern on the cam lobes. But the easiest way is probably to check the distributor gear wear.

I think i would play with the ignition capture settings first and see what that does. I would also manually retard the dizzy and set fixed timing before i started the engine with the new settings - who knows where timing will be after you reverse that setting.

vortec350s10

I agree that if it was cam walk or related, it wouldn't increase timing in a linear fashion. We'll see what happens when I get it fired up with the megasquirt. Hopefully it'll be rock solid being triggered off of the crank. I should know in a week or two when I'm ready to start it for the first time.

vortec350s10

Whoops double post