I have not been able to find anything out on the "loose stick" that Tugly has mentioned. I have found out about Cody but nothing on his site about loose stick. Does anyone know what this is?
Thanks

 

Injectors can sometimes be referred to as "sticks". If loose one can cause all kinds of trouble and if left alone for too long with wreck some havoc.

 

The injectors in HEUI engines are electronically controlled, but have a hydraulic intensifier piston or pintle, I believe. This hydraulic operated injector can move when activated if not properly torqued (the tiny undersized screws come loose). This movement changes the injection timing (the fuel injects later) and the amount of fuel injected (determined by fuel injection electrical pulse width-length of time power is applied to the injector).
Often a loose injector can have a characteristic clacking noise. Lack of engine power can be a sign of loose injectors or a worn out IPR-injection pressure regulator.

 

A loose "stick" (injector) happens to be my forte. The injector hold-down bracket is a form of a see-saw - not a flat surface in contact with the engine head. With a see-saw, the hold-down bolt torque is incredibly important - but the small bolt with an 8-mm head is incredibly susceptible coming loose. I tested the torque on a gajillion injector bolts never touched after the factory, and they are rarely at specified torque. A little "kiss" with an accurate torque wrench doesn't usually fix any woes beyond a little excessive cackle - but there are exceptions:

If anybody in the history of the truck has pulled an injector for any reason (swap, replace O-rings, inspect, etc...), then the odds of a loose injector go up exponentially. The most common practices that diminish the odds of success are...

• Re-using the tired injector bolts that have been torqued, strained, and heat-treated for hundreds of thousands of miles - then pulled and re-torqued.
• Using the wrong torque wrench, an inaccurate one, or improper storage of any torque wrench (not resetting to zero for storage) will corrupt the readings. The ft/lb wrench is not sensitive enough, and many inexpensive in/lb wrenches are not accurate enough.
• Improper treatment of the blind hole for the injector bolt. Not cleaning the hole or using too much lube or Loc-Tite can create a hydrolock condition when torquing the bolt.
• Knowing the specs and of the problem, but overtorquing to compensate.
• Not warming the engine to full temp, then shutting down to "hot torque" the bolts before putting the valve covers back on. This one is controversial - many "experts" will say something along the lines of "I've torqued plenty of injectors without hot-torquing and I've never had an issue. That doesn't eliminate the possibility they are lucky, many others are unlucky, they have better torque wrenches, or the "experts" expect more cackle from the engine they are fine with it.

It wasn't until the age of the fleet required many injector repairs/swaps that the torque problem came to light. I have gone so far as to buy a digital torque adapter (of good quality for about 50 bucks) to verify the settings on my torque wrench, and found every one of my wrenches to be off (high or low) by as much as 15 in/lbs. To make things even more frustrating, the wrenches are never consistent - I have to verify the torque every time I set them. Such is the way with a light torque setting on a wrench that costs less than $500.

Loose injector symptoms: Excessive cackle for sure, then it gets worse as the injector works its way loose even further. Louder cackle, air in fuel, air in oil, mixing oil into fuel, the dreaded "banging" and a miss, followed closely by the uber-dreaded damaged cup. The damaged cup puts fuel in the coolant, and a loose stick with a damaged cup puts combustion gasses in the coolant.

The good news is cups can be replaced with the engine in the truck (I don't know about vans), but it's a big job that takes a minimum of two days (sealant needs to dry before testing for leaks). Obviously - checking the injector torque is a lesser evil here.

 

And all our diesel fuel has air in it, which can become bubbles that are visible. These bubbles do not return to the dissolved state when pressurized. There is no way to know how this affects the way diesels run, but it certainly does not improve performance. Filter manufacturers have various ways to deal with removing the air. It does not cause loose injectors; just damage to the injectors, common rail components like pumps, piezo injectors etc. It may factor into the cackle in our trucks.

 

Thank you to everyone that has posted on this thread. You have all been a great help. All the items that I have replaced have helped the performance of my excursion so no loss on that.
I had to take the passenger side air intake off so while I was there I rechecked the wires going to the injectors, and I must have found one that was loose this time because its running good now. Its not dying anymore and the performance is really good. So at this point it is fixed, but if it starts to die again I know where to go to fix it.
Tugly thank you for you posts, I will definitely check the torque on the injectors to make sure they are correct. I will need to find a good torque wrench first.

Thanks again everyone.