Powerstroke Injector Popit Valve Info
Arguably the biggest problem with high mileage Powerstroke injectors is wear on the popit valve seat. On high mileage engines and engines that have not had proper maintenance and oil change intervals the popit valve face and seats will start showing excessive wear. There are a lot of theories on how to correct this but the only true solution is replacement of the injector.
As the popit valve seat wears the popit valve sinks further and further into the injector body. As it does this the armature that is affixed to the top of the popet valve moves further and further away from the solinoid and closer to the plate (or adaptor) afixed to the top of the injector body. On a new injector there is only .004" clearance between the armature plate and the top plate. So as you can inmagine there is not much room before they will come into contact.
As the armature plate sinks lower the solinoid that magnetically grabs and lifts the plate has a harder time lifting it and you start to run into runability issues like rough idle etc. In theory this can be corrected so that the solinoid will again be able to lift the plate by machining parts of the injector.
It's a nice theory and all and it does bring the armature plate back into spec in relation to the solenoid so that it can properly lift it. However it creates other problems and doesn't fix the actual issue to begin with. If you machine the bottom of the top plate to correct this you run a high risk of the armature plate hitting the solenoid. There are only a cople of thousandths of an inch clearance so if you machine much of anything off the top plate they are very likely to hit.
If you do something to lower the upper seat you are limiting the amount of travel that the popit valve has. The popit valve only moves a few thousandths and if you take even .002"-.003" off the travel that will equate to 20% or more restriction in travel. That means less oil can pass through the valve and push fuel into the engine. This may not be a big issue for stock or slightly modified injectors however when you are trying to get large volumes of oil in the injector to flow a lot of fuel reguardless what your ICP is you are going to restrict the amount of flow.
And still this hasn't done anything to address the real problem. The real problem is that the seat and valve are worn far beyond tollarance. As the valve sinks further into the seat it will start sticking causing more runability problems. If you rebuild the injector and try to machine to get the armature clearances back in spec the popit valve and seat will only contine to wear and cause more problems down the road. The ONLY way to properly fix this problem without replacing the injector is to resurface the valve seat and the valve face much like on an intake or exhaust valve in a head. Then machine the proper parts of the injector (which is NOT the adaptor plate) to bring the rest of the tolerances in spec. However noone makes a tool to machine the seat or face leaving the only way to properly fix this problem is to replace the injector.
At GTS Motorsports we do not recomend nor do we even bother to try to fix this problem. We will not compramise the quality of our injectors just to save some money over replacing the injector with a new one. We would rather only send quality parts out the door and possibly loose some sales than to compramise our quality by trying to correct a problem that can't be properly corrected to try to save some money.