Link Piggyback to MS3 - Injectors/Intake Manifold
 

I'm setting up a 2004 1.8L with a FM2 turbo in my 90. The previous owner used a Link Piggyback ECU, so right now the intake has holes drilled in it and a second set of injectors. I'm going to use Megasquirt in my car, so I want to replace the somewhat awkward two sets of injectors with a single set of larger ones.

I was trying to figure out where to find an uncut lower intake manifold and a set of decent sized injectors (the FC RX7 injectors sound popular). I don't have time to search junk yards anymore, so do you have recommendations on where to get them?

Does the lower intake manifold need to be a 01-05, or was that part unchanged when VVT was added?

The upper and lower intake need to match.

When I converted my car from a Link Piggyback to a Hydra, I initially both sets of injectors and used the piggyback ones in a staged injection mode. I dunno if the MS3 can do that or not, but if so then it's probably your easiest/cheapest approach.

Later on, after upgrading to 550cc RCs I made plugs for the holes. I used a bolt from the hardware store, one long enough to have an unthreaded smooth portion of the shank up by the head. I cut off all the threads, and then put an O-ring on it that fit into the tapered upper portion of the injector bung. One in each hole, then I put together a piece of aluminum that bolted to the aux fuel rail posts and held them in. It looked a bit ghetto, but worked fine and cost all of $12 at the hardware store.

https://www.miataturbo.net/attachmen...ine=1341893882

--Ian

of course it can!

Thanks Ian! The two sets of injectors seems like such an awkward setup that I didn't think it would work as well. It looks like the MS3 supports staged injection, so I guess I will at least start off running the existing fuel setup.

Maybe once I get it back on the road and have everything else sorted out, I will switch to a single set of injectors like you did.

Ben @diy actually went through the trouble of adding staged injection to his 99...and sourced an IM like yours with the extra bungs.

Despite searching for a while, I'm still a little confused about how to connect the fuel lines for my 90's return fuel system to this setup. Do I need to convert the main fuel rail to a fuel return setup via a 99-00 or aftermarket rail and then T the supply line to feed both ends of the FM second injector rail?

Would it work equally well to connect the supply line to the main rail and one end of the FM rail, and then a FPR and the return line to the other end of the FM rail? It seems like this could be the quickest way to get the car up and running, but I didn't know if the FM rail needs supplied from both ends like FM's original configuration to provide even fueling to all the cylinders.

In the FM kit, the aux rail is simply installed inline before the main fuel rail.

--Ian