I would like to learn as much about injectors as I can. I have a basic understanding of how they work but now I'm reading about poppets and shims and I gots to know. After all, my truck is aging (go figure) and injectors may well be on the list. I do not start as well as I think I should.

So...here's what I know. Fuel is fed to the injectors somehow and I believe it is through a channel (rail) inside the head from the filter, which sits right behind the HPOP reservoir. Aaaa hell, rather than lay out what I think, could someone please just 'splain it or point me towards a write up on it so I can read up? That would save some space on here. Then I (we) can ask questions and figure it out.

Thanks,
Mark

 

HEUI - How High-Pressure Oil Injection Systems Work - Diesel Power Magazine

 

Thank you for that link, great explanation of the HEUI system. It describes the system well and why the later stuff is better. Reps sent.

Other than the poppets what/where are the other wear points on the injectors? Is there an efficient way to have them tested?

The next time I am under there I will check out those poppet valves and see what I find. I can now understand why the later IDM and HPOP off of my short bus will benefit my E99.

Now, AB vs AD injectors. I have AB's in the truck but also have a set of AD's on hand with about 225,000 miles on them. Would a switch to the AD's require any tuning adjustments? My PCM is live tuned. Would I be wasting time to check poppet clearance and install those used AD's in my truck?

 

Tons of good information in that article, Dan.

I don't think of it so much as a memorization of all the part names - poppet valves and such. My brain goes to a spray bottle (like for Windex). The HEUI injector doesn't inject fuel directly the same way a spray bottle doesn't spray directly. "Directly" would be to open a valve and the pressure of the working fluid would inject or spray (fuel in the truck or window cleaner in the spray bottle).

Using the spray bottle to demonstrate the components of our HEUI system, the "High Pressure Oil" is your hand. You squeeze your hand on the trigger (akin to the solenoid firing and allowing the High Pressure Oil into the injector), and this presses a "plunger" to force the fluid out a nozzle - this makes spray. Our HEUI injectors have a plunger as well - this keeps the oil away from the fuel. This plunger in the injector is also an "intensifier" - think Pogo stick. Your whole body fits on something with the footprint of a silver dollar - giving that foot pad a very high pressure in terms of pounds per square inch.

So after spraying, the head of the spray bottle is out of fluid - much like an injector is drained after firing. The head now needs a reload of fluid for the next "injection event" so you let go of the trigger - the pump in the head now draws fluid up from the bottle (fuel tank) into the head. In our HEUI system, we have an external pump to push fuel into the injector - this is the major difference from our spray bottle.

There you have it - grab a spray bottle and learn how our injectors work.

 

In my conversations with Tim @ PIS and Jim @ Rosewood...one issue is the poppet seat that is machined in to the injector body itself. If I had the time, or higher desire, I'd figure out a way to remachine the seat...thus creating an overwhelming supply of injector bodies to be re-manufactured.

 

I am familiar with the chamber for the fuel to enter into and get pushed into the cylinder for combustion, my old Cummins' injectors worked the same way. The difference there is that they are mechanically operated just l like the valves are off of the rocker arms and their own rockers. To goose that one there were different 'buttons' that could be inserted into the fuel pump in a jiffy that would increase fuel pressure. I don't know about using different injectors but I suppose it would have been possible. For the life of me I could not figure out how motor oil was used in these things. Also in that Cummins when an injector O ring failed the flow was diesel into the motor oil, not the other way around.

I gots to get my hands on a sacrificial injector and rip it open to see what's in there. I do have a precision lathe out in the garage so if I learned how to use it I could maybe machine those poppet surfaces.