M103 EFI Parts Needed?

[Kyngfish]

Planning on doing an EFI conversion, probably fuel first - and although I see a lot of older posts about people doing it, not a lot of posts about the process. I've been reading through the megasquirt manual, and trying to come to grips with the things I need specifically for the M103 to make this happen. Hoping someone can point me in the right direction here:

- MS2 V3 - check - I'll probably also get the relay box. I have some experience with putting together reasonably complicated PCBs so this doesn't concern me all that much.

- MAF/MAP - My understanding is I can use the MAP on the stock system and it works fine?

- TPS - I can put one into the throttle body, but most things I read say it's not really needed

- O2 sensor - get a wideband that works with MS2?

- Injectors - EV6 Injectors in the stock manifold with the M104 fuel rail. Since they're discontinued anyway, I assume I can just toss the fuel injector bushings and slightly bore out the holes so the bosch injectors fit?

- What about fuel delivery? I know the stock pumps are probably OK, but do just bypass the fuel distributor?

- For ignition, I'm going ahead and getting the appropriate toothed wheel, but aside from ignition coil, igniton module, and new spark plugs - what else do I need?

[duxthe1]

Put a TPS on it. TPS AE is easier to set up. Go to a pull n pay to get enough connectors to build a harness. The 104 rail has a regulator built in and the best bet is to also pull the feed and return hose from the rail donor. I'd plan to **** can all of the CIS stuff which means you'll need to figure out idle air routing, engine breathing, and air filter. The idle air passages in the intake manifold flange can have issues with fuel robbing between adjacent cylinders if batch fired. If at all possible, do full sequential.

[Kyngfish]

Thanks for this.

I’ve been continuing to read and so far here’s my plan.

- Get an extra intake manifold from a donor car at the pick and pull and start building it to handle the fuel rail and injectors. Understood on the sequential injection, so that means probably MS3.

- I’ll probably cut off the manifold and build a new section to the air intake from aluminum. I don’t know how to TIG weld, but I have a MIG welder and I’m pretty sure that will work fine, though it may not be as pretty.

- That also means I will get a throttle body from something else with a TPS. I’ve seen and heard Volvo or BMW, is there a specific size I should shoot for?

- I guess that also means I’ll have to figure out the throttle cabling as well. Standard intake with a cone filter is probably where I’ll end up for now.

- MS3 will also give me coil on plug ignition, so I can also ditch the dizzy.

- The only other thing I don’t really know how to quite manage or route is the idle valve - but I’m guessing I can just use the current one, and figure out the routing?

[Frank Reiner]

Kf:
Consider a minimalist approach for openers; a bit of time spent crawling before attempting sprinting can be useful.
The MS MicroSquirt serves well as a fuel only controller, and can be triggered from ignition for engine speed information.
The existing ignition system will be retained complete.
The existing idle air system will be retained. If the matter of possible fuel crossover in the idle air passages is thought to be a real concern (the condition exists with the CIS also) the passages can be blocked, and idle air introduced into the plenum.
The existing throttle body has a switch mounted on it which can be replaced with a TPS.
Once the CIS air flow meter/fuel distributor package is removed an air filter can be attached to the throttle body.

[Kyngfish]

Originally Posted by Frank Reiner

Kf:
Consider a minimalist approach for openers; a bit of time spent crawling before attempting sprinting can be useful.
The MS MicroSquirt serves well as a fuel only controller, and can be triggered from ignition for engine speed information.
The existing ignition system will be retained complete.
The existing idle air system will be retained. If the matter of possible fuel crossover in the idle air passages is thought to be a real concern (the condition exists with the CIS also) the passages can be blocked, and idle air introduced into the plenum.
The existing throttle body has a switch mounted on it which can be replaced with a TPS.
Once the CIS air flow meter/fuel distributor package is removed an air filter can be attached to the throttle body.

That’s good feedback, but I’d rather buy once and cry once. I have a few other cars so I’m not worried about having to sort through kinks and take my time here. The most likely scenario is that I’ll buy a spare engine and build it while I’m still driving on the other one. Total newbie to the EFI conversion world, but I’ve been wrenching on my cars since I was a sprite back in the 90s - so hopefully that will help me avoid effing up too hard.