Megasquirt Distributor Control
 

As the title hints at: i'd like to set up an MPFI system using a megasquirt (as i know others have done before). I'd also like to have the Megasquirt control the timing once the CCC Qjet comes out. From the research i've done, my 86 LG4 has the big cap CCC distributor (which i believe is a 7 pin HEI module). I've seen a tech article from DIY Autotune where they do this on an older SBC (link below). Has anyone done this? Am i missing any important details? Thanks for the help.

https://www.diyautotune.com/support/tech/install/chevrolet-gm/carb-to-efi/part2/

Re: Megasquirt Distributor Control
 

Yup. Did you buy the Megasquirt yet?

Personally I like the Microsquirt and Microsquirt module. You don't have to modify things to change how it works, and it's a surface mount board meaning less prone to issues. (MS2 is through hole).

I'm using a Microsquirt module inside a stock GM ECM case so it's plug and play:

http://members.cisdi.com/~anesthes/projects/megasquirt/

-- Joe

Re: Megasquirt Distributor Control
 

I haven't bought the Megasquirt yet, i'm focusing on the hard parts first (fuel rails, throttle body, etc). I figure they'll keep me busy enough to spread out the cost hit over a few weeks.

For a standalone FI setup (that will accomodate a future 383 with new injectors), do you think a Microsquirt would be better? I was under the impression that it wouldn't control timing electronically like i want to do. I have and will be keeping a manual trans if that makes a difference (no auto transmission functions needed)

Re: Megasquirt Distributor Control
 

A microsquirt is the same as a megasquirt, it's essentially a MS2 but better electronics. The only different is the stepper IAC circuit is external (add on board/module/etc), and it cannot fire a coil directly (requires an ignition module or ignitor). You'll be using an HEI distributor + module.

-- Joe

Re: Megasquirt Distributor Control
 

I see on the website thag the IAC mod kit won't work with the standard Microquirt, only the module board. Would i miss not having an IAC valve?

Re: Megasquirt Distributor Control
 

The Microsquirt uses an external iac module. Diyautotune doesn't sell them. Google Microsquirt stepper adapter. Two companies make them. I have the Canadian one in my shop.

This is the most common one:

http://www.efisource.com/shop/micros...epper-adapter/

But I prefer this one:

http://efi.ttrignition.com/products.html

Might have to email him. That one converts a PWM signal to a stepper.

You can also build one.

-- Joe

Re: Megasquirt Distributor Control
 

I like what you're suggesting, looks much more sturdy and easier to package than a megasquirt. Any thing else i should know? I'm new to this, trying to make sure i'm covering my bases.

thanks,
harrison

Re: Megasquirt Distributor Control
 

Make sure you install the latest ms2extra firmware, and read the documentation at the ms2extra site.

The Megasquirt can run two operating systems B&G and Ms2extra. They are functionally different, and when google searching a lot of the information is based on the B&G software, which doesn't apply to Ms2extra. This causes a lot of confusion and problems.

Again, I prefer the Microsquirt module because you can stick it in a stock ECM case and it's very expandable. The way mine is setup (first link I sent you) It's plug and play with my factory '88 TPI harness. The only thing I had to do was use the MAF wires for a MAP sensor.


-- Joe

Re: Megasquirt Distributor Control
 

I ordered the standalone microsquirt with harness yesterday, along with the intake manifold, fuel rails, and throttle body. Today i'm gonna order the rest of the odds and ends I need (fuel line, fuel pump, injectors). Hopefully I can get this up and running before the end of the calendar year.

Re: Megasquirt Distributor Control
 

Did you order the IAC adapter too?

-- Joe

Re: Megasquirt Distributor Control
 

Not yet, i wanted to confirm with you what (i think) i found on the internet: Chrysler and GM IACs are basically the same right? The Holley TB i ordered comes with a Chrysler IAC but all other sensors are GM style.

Re: Megasquirt Distributor Control
 

They are not. The Holley 4bbl throttle bodies come with Christler IAC's, which are wired differently. I'm not sure about the TPI throttle bodies.

-- Joe

Re: Megasquirt Distributor Control
 

Well dangit. Guess I need to find a different throttle body then

Re: Megasquirt Distributor Control
 

You can wire it, just need to know which wires go to which coils.

MS has the ability to do a IAC test so you can command the pintle in and out.

-- Joe

Re: Megasquirt Distributor Control
 

Joe, i’d like to maintain my stock tachometer after this swap. Can I just tap into the appropriate wire to run the tach and give a signal to the Microsquirt?

Re: Megasquirt Distributor Control
 

Just connect the tach to the negative side of the coil, just like stock.

I'm using a factory TPI wiring harness, so my Microsquirt (module) has a Delphi56 end on it (86-89 TPI, TBI)

What are you doing and which harness did you order? Are you running all new connectors to your sensors, ignition, etc, or splicing it into an existing harness?

-- Joe

Re: Megasquirt Distributor Control
 

Tough call. When you first start to tune any ecm on a new engine you want to tune it with the IAC motor turned off. I am always able to somewhat tune for stumbles with added ignition timing in the lower rpm and vacuum cells of the ignition table. Once the engine can idle efficiently and recover from deceleration I turn on the IAC motor and then tune the IAC. The IAC is great for cold weather starts, to save you on unusual stumbles or if you run A/C or if you are using a higher power accessory and the alternator tries to bog the engine at idle. If you only drive the car in warm months though you would be OK without it. I had no IAC when I ran MegaSquirt I.

PS. On a nerdy level I just got my book back from being autographed by Jerry Hoffmann and Matt Cramer! They had to "fix" my MS3 extra after the interior fire.

https://cimg3.ibsrv.net/gimg/www.thi...cc0837cd15.jpg

Re: Megasquirt Distributor Control
 

On new builds, I fully extend the pintle, unplug the IAC and get my minimum idle speed (hot) with the throttle screw. Then I plug the IAC in and used closed loop IAC.

On newer GM OE stuff, they reply more on spark advance than airflow to stabalize the idle speed. A lot of guys have been ditching IAC's all together on aftermarket builds and just using spark. I have not tried.


Both great guys. Are you a member of the 'Guilid of EFI tuners' ? They contribute there regularly.

I wish thirdgen.org had more active EFI discussions. Most of the members here just don't have experience with stuff that is newer than 30 years old, so it's impossible to get healthy discussion. We had a great discussion the other day about using things like ATS's ECOP to troubleshoot ignition problems at specific combustion events. There is really some amazing stuff out there.

-- Joe

Re: Megasquirt Distributor Control
 

I'm not a member of that group, their knowledge far surpasses mine. I'm not a Facebook person either. I enjoy reading about all the newer stuff that comes out, especially the MS and DIY autotune stuff, but with the bills that little kids bring right now I don't have the ability to constantly upgrade ecms and build engines and combos to really have relevant conversations and first hand knowledge about the newer stuff. My wife allows for a one and done policy (for at least a couple years, hehe). I can help with MS 1/2/3 stuff like this and general efi theory but that's it.

Re: Megasquirt Distributor Control
 

Joe,

I ordered the standalone harness and new sensors, i thought that would be easier than trying to work with the factory stuff since i would have needed to add some stuff. I’ve been making slow progress on this, been busy with work.

I’ve got the intake/tb on, waiting on injectors to mount the fuel rails and finish the fuel lines in the engine bay. I wired up a new relay and fuse panel to power everything, gonna mount the ECU next and start wiring in all the sensors.

I feel okay about doing the wiring, think my biggest obstacle will be the fuel pump. I bought a new sending unit for a TPI Camaro and put a Walbro 255 on it, but i’m unsure if I want to try to drop the tank myself (working in a 1 car garage at an apartment complex). Also, do you know what kind of connection a carb sending unit would have to the supply line? The new one i got has what i assume is the 16mm fitting on it, and i wonder if the carb unit is just hose clamped on.

Re: Megasquirt Distributor Control
 

I used adapters to go from the 14/16mm whatever they were fittings to -6, and ran braided PTFE (not AN) hose all the way to the rail.

The return is just a hose clamp if I recall. I went from a -6 to a barb and used FI hose to go between the nipple on the return and the barb.

What is the rest of the engine? An LG4?

-- Joe

Re: Megasquirt Distributor Control
 

Yeah it’s a bone stock LG4 for the time being. One day i might like to put a 350 in there but in reality that’s probably a long way down the road.

I bought some AN to 3/8 and 5/16 hardline adapters for the engine bay side, since i’m not running big power, my plan was to re-use the factory feed and return lines so I wouldn’t have to run a new line to the tank. I was hoping to just attach the new sending unit to the old lines and be done...

Re: Megasquirt Distributor Control
 

Re: Megasquirt Distributor Control
 

Are you using a large cap or small cap dizzy?

On the small cap, you have 2 plugs that go to the module. One from the main harness which has 4 wires. A second with two wires which go to one side of the coil. Then the other side of the coil has a white and red wire going to the main harness.

On a large cap dizzy like I'm running (I.e L98 Corvette), you have a large connector with 4 wires that goes to the main harness. A two-wire connector that goes from the module to the cap.Then you have an individual thick red power wire, and a white tach wire from the main harness that goes to the cap.

I've gone back and forth in my head about which is better. I have a billet large cap right now, but I noticed the cap retention kinda blows and I bet it has some spark scatter.

I have a billet small cap on the shelf, but mounting a remote coil with the miniram kinda sucks.

-- Joe

Re: Megasquirt Distributor Control
 

A bent piece of 18 gauge steel, two rivets and three machine thread bolts with a sprinkling of paint.

https://cimg5.ibsrv.net/gimg/www.thi...5780788473.jpg

https://cimg3.ibsrv.net/gimg/www.thi...dceaa041a8.jpg

Re: Megasquirt Distributor Control
 

is there a third option? I think it's a large cap (no external coil). I have the flat 4 wire connector, and the only other connector is a 3 wire plug that goes into the coil on the right side of the distributor (looking at the engine from the front). I don't think I have any other wires.

Re: Megasquirt Distributor Control
 

Nope. You definately have a thick red power wire, and a thin white tach wire that goes to the coil. What year/application is the harness? I should have a schematic.

-- Joe

Re: Megasquirt Distributor Control
 

[QUOTE=Tibo;6205307]A bent piece of 18 gauge steel, two rivets and three machine thread bolts with a sprinkling of paint.

That worked out pretty good :)

I want to switch to CNP, but don't want to sandwich my crank trigger between my balancer and pulley. When I have some ambition, I'll weld it to a stock crank pulley.

-- Joe

Re: Megasquirt Distributor Control
 

Re: Megasquirt Distributor Control
 

[QUOTE=anesthes;6205463]I've wondered, why don't more people use the MSD distributor for the crank trigger as opposed to the trigger on the crank? Is there an issue with the MSD distributor style?

Re: Megasquirt Distributor Control
 

[QUOTE=Tibo;6205469]Link me to it and I'll check it out.

The Ms needs a crank trigger of some sort. I imagine if the dizzy has enough teeth it would work. I'd think you need at least 60x to have enough resolution.

-- Joe

Re: Megasquirt Distributor Control
 

Re: Megasquirt Distributor Control
 

Your dizzy should look like this:


https://cimg3.ibsrv.net/gimg/www.thi...1d2f2f748e.jpg

The 4 wire connector goes to the main harness. The other connector goes from the base to the cap. The middle wire is ground.

If you look at the cap:


https://cimg1.ibsrv.net/gimg/www.thi...fc052441e5.jpg

You'll see it takes a fat red power, and small white tach. These should be part of the main harness.


-- Joe

Re: Megasquirt Distributor Control
 

Re: Megasquirt Distributor Control
 

I usually idle around 22-24 degrees. But it's very dependent upon the cam being used, compression ratio.


https://cimg5.ibsrv.net/gimg/www.thi...c856de3107.jpg

Re: Megasquirt Distributor Control
 

Another important area for aftermarket hoped up engines that Joe's table illustrates is a stable idle region. You should be able to get your idle steady to a single cell, maybe two, but you should expand the numbers out to the periphery cells. Doing it that way admits that the idle may be somewhat dynamic and if it enters a neighboring cell it keeps the fueling and spark requirements the same so you aren't entering into a wandering idle situation brought on by a different value in every cell.

Re: Megasquirt Distributor Control
 

Re: Megasquirt Distributor Control
 

I do that with the cells with the lower vacuum readings and lower RPM readings. Ends up being one of the corners. I add in a few degrees and let the idle valve open up. I think that's in a lot of efi tuning sources I own or have read.

Re: Megasquirt Distributor Control
 

Like that tactic vs using the idle spark adder ?

-- Joe

Re: Megasquirt Distributor Control
 

Re: Megasquirt Distributor Control
 

So what is the point of swapping out this ECM for stock? More reliable? Easier to tune? Can't use HP tuners with this I assume.

Re: Megasquirt Distributor Control
 

I'm thinking you have a bad ground or something in the dash.

My cluster is having problems too - like you I have a brand new spectra sender. My fuel gauge reads 1/2 when it's full, my tach sometimes jumps, especially when my turn signal is on. Something I have to deal with soon .

-- Joe

Re: Megasquirt Distributor Control
 

He removed the stock ECM (which only controlled timing and minor fuel mixture as it was a CC carb) and replaced it with an advanced Megasquirt. You tune Megasquirt with Tunerstudio.

-- Joe

Re: Megasquirt Distributor Control
 

Oh ok. Thanks.