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Just got some STI injectors

Posted: Thu Apr 26, 2007 12:40 am
by IronMonkeyL255
Yellow-top side feed injectors supposedly out of a 2004 STI

Just a few questions:

What is the purpose of the grey caps on the top of the injector?

One of the injectors I received was missing the cap, while another had a cracked cap. I used a razor blade and popped the caps off of the others, and they didn't seem to be on there very tight, so I am guessing it isn't really pertinent to the operation of the injector.

What is the little brass thing under the aforementioned caps?

On the injector that was initially missing the cap, that piece seems to sit slightly lower in the body of the injector than the others. If this piece is supposed to move, is this acceptable? All of the others seem to be at the same level, so it had me wondering.


I got these off of eBay and just got them today. If these are screwed up, I will protest and get my cash back, so quick responses would be appreciated. It will be quite a while before I install these, so 'just put them in and find out' is not an option.

Posted: Thu Apr 26, 2007 1:15 am
by IronMonkeyL255
Looking around, it looks like Perrin prefers the core injectors (that they modify to squirt 816cc) with the caps on, so it makes me wonder.......

Posted: Thu Apr 26, 2007 3:57 am
by douglas vincent
You need the caps. They are used to get the final amount of pressure to hold the injectors tight. If you remove them, the injectors leak out the top. I know.

Posted: Thu Apr 26, 2007 4:21 am
by 555BCTurbo
I hope you have some variety of piggyback or standalone engine management...

Posted: Thu Apr 26, 2007 6:38 am
by IronMonkeyL255
I don't yet, but I intend to before installing them. I'm just waiting for the guys over at Element Tuning to get the plug-n-play Hydra unit finished.

Though it looks like I will be returning this set, unless someone knows where I can get just the caps.

Do you mean they are basically spacers that hold the injector firmly wedged between the cap and the rail? If so, couldn't I just make some spacers to do the same thing?

I have a set of n/a rails with injectors on the way as well. Do those have the same type of cap, and will they fit?

Posted: Sun Apr 29, 2007 11:49 pm
by IronMonkeyL255
Just as a little closure, the rails I got came with injectors that had little rubber spacers on the top. They fit the STI injectors perfectly.

Now I'm polishing the injector caps while I'm bored.......