Hey everyone, I have a 99 XJ that I'm always tinkering with. This weeks project was to add some of those fancy 12 hole injectors to see if I could notice a difference. Watched a few videos then dug into it, trying to use best practices (torque wrench, silicone grease, electronic contact cleaner etc. This is my first time doing injectors and when I pulled the stock ones out I noticed they didn't have plastic caps at the ends, and neither did the ones in the videos I watched. So I assumed those little plastic holders at the tips were just there to hold the O-rings on during shipping and I popped them off (seemed like they would melt in the cylinder?). Well, turns out I was supposed to leave them on. My question is: Is this a big deal, do I need those in there? I can always pull them and add the retainers, but only if it actually matters? Thanks for any advice. Appreciate it.

 

NO....there should not be anything but o-rings at either end. The clear plastic caps are there to keep dirt out and protect the ends until install

 

I think you both need to view the search results in the following link. https://duckduckgo.com/?q=fuel+injec...=v314-1&ia=web

 

http://www.tomco-inc.com/Tech_Tips/ttt37.pdf

the above links explains the use of the caps.

In brief, pintle type injectors mounted close to the intake valve can cook when engine is off from built up heat from the combustion chamber, specially on injector next to an open valve. This heat can cook the gasoline residues on the tip of the pintle, eventually causing enough cooked on deposits to harm spray pattern. The caps can reduce this bad effect. Some caps also are an aid to spray pattern.

So if she is supposed to have a cap, use the cap.

 

Whoops, the snake oil salesmen got him.


Your assumption was partially correct. The caps are certainly there to hold the O-rings, they have nothing to do with shipping however.

Lol. Do you have a different engine from the rest of us? The Jeep straight 6 is not direct injected.

The caps make sure the O-rings stay secure on the tip of the injector at all times. Especially during removal. When these early port fuel injected engines first started being serviced, there were no plastic caps and technicians were leaving O-rings in the manifolds. They would put new injectors in and basically double stack the O-rings, causing a whole slew of issues. So just make sure that you can account for all of the O-rings when you service the injectors next time.

 

Hey, thanks for this, I appreciate it.