Injector reinstall
I’m still waiting on the supercharger rebuild to be finished. They’ve had it for a while now; not ideal, but it gives me some space to take my time carefully putting things back together.
I installed the injectors over the weekend. They turned out to be a bit of a saga, but they are sorted now and I have a plan for the future.
I got a set of EV14 550s (thanks
@RYU!) to replace the RC 550s:
I was originally planning on installing the EV14s now since everything is already apart, but ultimately decided to stick with the RCs in the near term. Even though they are the same size, the new injectors almost certainly will require some part of the fuel map to be retuned. I’m replacing a whole bunch of parts in this pass, moving the WMI nozzle, etc., if one of those things makes it run differently, it’ll be hard to tease apart issues from some replaced part and the new injectors. Like what if it’s hard to start? Is it the injectors or messed up vacuum routing?
The plan is to get it running the same or better than before with the RCs, then do the EV14s on their own and retune parts of the map with the injectors as the only variable.
Problem?
The RCs were already in the car! Reinstalling should be straightforward! Haha nope, lol aftermarket parts…
When I went to remove the rails, the rear rail bolts were straight up loose. Like loose loose, hardly hand tight. I could move the rail around with pretty minimal pressure. Yikes.
I initially thought, well it just needs to be tightened, eh? Turns out tightening the rail bolts forced the injector so far into the rail that it over-squished the grommet and made the harness plugs not fit on the injectors. My guess is that someone _intentionally_ left the rails kinda loose so the plugs would fit. Derp. Seems like a fire waiting to happen.
Here are the grommets over-squished:
With no tension on the rail bolts, there was like a 1/4” between the rail and the stand-off, even with over-squished grommets:
The tl;dr is that either the injectors were too high, or the rail standoffs were too short.
On the manifold side, there is a rubber seal:
On my car, there was a 6mm aluminum riser under each seal. For reference here is the manifold seal without the riser:
Lower, eh? At first I thought this riser was necessary for some reason, maybe injector to manifold interference? After some tinkering I realized the riser was probably not at all necessary and without, the injector seems to be better positioned within the manifold.
With the riser, the injector is tucked far back into the manifold. These injectors must have a pretty narrow spray pattern…
Then without, the tip is much more flush. Possibly better for atomization cause fuel won’t gather on the manifold edges? Idk.
Install
With that sorted out, I could install them. The injectors got new o-rings, grommets, and a little silicone grease:
The old standoffs were about 15.5mm tall and would probably have worked, but they put almost no tension on the grommet/injector which made me nervous. I wanted a tight seal on the lower grommet, so here it is with a 1/2” standoff plus a 2mm spacer: 14.7mm tall, about 1mm of space to put more tension on the injector when tight:
All tight now, it feels like just the right amount of grommet squish, tension on each injector, and plenty of room for the injector plug:
Any CTSC people out there know why there was a riser on the injectors in the first place?
. I won't even get to install mine for another few months. Tried to make it thick enough so that it wouldn't warp from the heat.
