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MegaSquirt II Preparing for Install


naviathan

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Ok, I built an MS-II box I was trying to sell but apparently people want the MS-I boxes more (probably because they're cheaper). Anyhow, since the box didn't sell (I was asking $400) I'm considering installing it on my 81 daily driver. It's an NA all stock engine and I plan to keep it that way as I really just want reliable and good gas mileage for this car. Here's my questions:

1- I don't have nor want a turbo distributor to do this. Can I use the stock NA distributor and how?

2- Obviously I want to eliminate the AFM. So in effect I need to drill and tap an air temp sensor in the intake right? The MAP should take care of the measurements.

3- Idle Air Control...Ok I've done a lot of thinking on this. Can I just pull one off a 90's Camaro or some kind of Chevy and tap the intake for that as well, or does it have to be in an enclosure? I can't seem to wrap my mind around exactly how this works. Does the sensor itself allow air in or is it nothing more than a solenoid that opens a passage in the enclosure?

 

Ok, from my reading I think the stock distributer is a VR type, but every layout I've seen show an HEI triggering the coil. Is that must? I can get an MSD 6AL from a friend for cheap if I need to, but if the stock system fires the coil, why can't MS do it? Anyhow, I've been shoving so much info into my head that I really need to just let it all digest and get some more basic answers I guess. Any help is appreciated.

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You can lock out the timing in the stock distributor and use Megasquirt's VR conditioner if you like. That should work, but locking the timing out can be a hassle.

 

And yes, IAT sensors work as you expect. Pretty straightforward to install.

 

The IAC valve moves a plunger that opens a passage inside an enclosure. We have a remote mount IAC body if you need someplace to install one.

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So it would be easier to run the MSD then? I can easily get one. As far as the enclosure for the IAT goes, I figure I can pull one from whatever vehicle I get the IAT off of. I have a friend that owns a junkyard. I do a lot of business with him.

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Nav, I've been perfectly happy to use the stock ignition on two of our 280z's with MS-II. If you got a good dizzy and ignition module, I think it is a good way to go for NA. Later, you can always "upgrade" to using the VR circuit with the onboard '921 ignitor.

 

To get the project on the road, I adjusted the internal AFM spring so that the flap is forced open instead of closed. I'll remove the AFM later. I just stuck the IAT sensor in the hole in the AFM to TB boot.

 

There's nothing wrong with using the stock Air Regulator valve. Just wire +12v from the fuel pump supply so that the valve will close over a couple of minutes. I'm in the process of hooking up an IAC and body off a Buick 4-cylinder. Ended up with something similar to what Nish did. In fact, he put up some nice pictures:

 

It looks like he used the same IAC body as I did with a blockoff plate on the bottom, drilled and tapped for 3/8" barb-to-NPT fittings. I made an adapter to bolt the IAC body over the spot where the CSV used to go, but his setup looks pretty easy to put together:

GM_IAC_MOUNT.jpg

 

I prefer the IAT before the throttle valve but here's the way Nish did it. Nice looking.

THROTLE_BODY.jpg

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Right. The stock ignition takes care of spark. Makes it very easy to get up and going. I had no hardware or software tweaking to do on the ignition side of things for MS-II.

 

I like starting off simple and doing little upgrades. I've got an EDIS wheel on a spare damper and am working on the sensor mount and will convert over at some point.

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Just so I have this straight, I have my MS-II setup as such (this was what I figured a good generic setup would be):

- IAC - Stepper Motor

- Ignition - Hall/Optical/Coil Neg - Coil Neg. Circuit installed, jumpered D1 & D2

- PWM Flyback Dampening circuit and standard circuit installed.

 

So I what do I need to leave in the original system to keep the stock VR distributer and ignition box working? From what I have read, does the attached image show what I should need?

v3ext_wiring_thumb.jpg

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