^^ no chit...
we just added another mechanic who worked at Ford for 8 years...and he was surprised when 'got' to do all 8 injs in a 6L on his first day here, LOL
not to get too off topic...but think of the spool valve as a piston in a cylinder bore...without piston rings.
the solenoids (when energized by the FICM) pull the spool L or R (open or closed) to allow the HPOil to enter the injector...
when the 'piston' (spool) get's loose(r than it should be)...it can get a little cocked sideways and will drag on its' bore...and since there isn't anything mechanical pulling it (simply a magnetic force)...the drag of the (loose) spool won't allow it to move consistently. So when the spool (occasionally) sticks...that injector doesn't fire..at least not that time.
Back when we were remanufacturing the 6.0L injectors...we often had some pretty PO'd customers...describing the intermittent misfires just like this.
It took us quite a while to figure out WHY we weren't catching these issues on our injector flowbench...but we finally caught on.
While flow testing the injectors (minimum 4000 shots at various pressures and pulse width to simulate idle, part throttle, WOT, etc) we wouldn't EVER let a set of injector leave until they were within 1-2% of each other...
the PROBLEM wasn't that we were dealing with an injector that was 1% high or low when compared to the others...
We were dealing with injectors that would be 100% low 1 or 2 PERCENT OF THE TIME!!!!!
bigggg difference.
you'd NEVER feel a 1-2% difference in injector balance in a truck, IF the questionable injector WAS only 1 or 2% off all the time...but...if the injector is NOT firing at ALL 1 or 2% of the time...then that's what you feel in the truck as an intermittent misfire...
we quit remanning the 6.0L injector about 4 years ago...and since selling & modifying the OEM Ford injectors..have had very very few problems...and lots of very happy customers!
Daily, I get calls from customers who purchased reman injectors from XYZ company...who have the exact same symptoms as their stock injectors had...which is no surprise since the spool valve can't be successfully remanned.
It would be like trying to rebuild an engine without having 10 or 20 over pistons...no matter how good the machine work it...if you can't regain that lost clearance between the spool and the bore...the injector is still going to have the exact same problem...
The injectors available at the Ford (or International) dealer are the only injectors that come with new spool valves...Alliant Power 6.0L remans are just as crappy as the others in our experience...
any injector shop can disassemble the injectors...clean them, replace nozzles, cut pistons, etc, etc...but the spool valve is going to have the same wear & issues when it is shipped out as when it was received by XYZ company...
