While I can't speak for M-S-G, I've rarely found a bad injector to show itself externally - with exception of fuel stains near the tip or a rolled O-ring. The guts have the moving parts, and a steel housing makes a terrible window.

 

Nope. Nothing. Haven't even heard of what you're describing.

Everything was looking good, even the orings and copper washer.

 

On the contrary...

The change between the AD and the AE Long Lead Injector #8 is very much on the fuel end. The specific difference inside the injector that provides the longer lead time is in the machining of the annular groove on the fuel plunger. The width and location of that groove relative to the spill port inside the barrel determines the gap in time between the first and second injection of fuel on split shot injectors.

One of the 99.5 updates was to increase the width of this annular groove to increase the time between shots in order to improve emissions.

There are manufacturing tolerances in any mass produced machining process, however small, and this is true for the plunger and barrel. The original long lead injectors released in latter half of 2000 were initially culled by CAT, not specifically built, as being on the extreme end of an acceptable tolerance of having a longer lead time. It was found that putting these injectors in hole #8 could help deal with the fact that the adjacent hole #6 injects high pressure fuel back into the lower pressure fuel supply rail from #6's spill port in between shots. That pulse from #6 effected the fueling of #8. Changing the lead time of #8 was a way to mitigate #6's effect on #8.

In any event, the long lead injector is made long lead on the fuel end of the injector, not the high pressure oil end. The pulse being mitigated is in the low pressure fuel rail, not the high pressure oil rail. The high pressure oil within an injector is controllable on the fly by the electric solenoid. No need for a different injector to make changes to the control of the HP oil.

The high pressure fueling however, is not directly controlled. It is indirectly motivated by the high pressure oil, and then managed through machining... whether it is the width and location of the annular groove, or the number and diameter of the holes in the nozzle, or the cutting or replacing of the intensifier piston to increase the stroke length within the injector... fueling inside the7.3L HEUI injector is more predetermined by machining... otherwise there would be no need to switch out physical injectors to obtain various "Stages" of performance fueling.

 

What did you get for a replacement? New or Used and from where? I'm in the same boat. Thanks

 

Clay. New. Getting 2 more soon. Oh joy.

 

If your changing that many, buy all new. No more problems.

 

great info. sounds like you know your way around an injector.

So, the issues seems to be fuel related vs oil pressure related. In the case of adding a fuel crossover kit and doing the check valve delete would that be more helpful for the #8 noise issue?.

I was planning on doing the FXO? and replace OEM fuel line with 3/8" SS braided racing lines on AN fittings. This is hoping to help extend injector life, increasing HP , and helping to quiet the clatter noise down.

 

I did cvd+ ss lines (larger with an fittings)
Got real quieter truck after that.

No crossover.