HEUI Fuel Injection Failure and Solution

The Documented Problem Engines prone to stiction issues are the PowerStroke 7.3 engine from 1994 to 2003, the 6.0 from 2003 to 2007, the Navistar T444E and especially the VT365 which was manufactured from 2003 to 2007. Q:What is stiction? A:A conjunctive form of Static Friction As it relates to injectors, it is simply pistons which stick in their bore, to a level which retards the initial movement.

The 6.0L runs the high pressure engine oil system much higher than it was in 7.3 L PowerStrokes “4000 psi” causes shearing of oil polymers reducing a 15W40 viscosity oil to a 30 weight in as little as 1,000 miles Can result in increased exposure to wear because of reduced lubrication protection

6.0L Facts Contains extreme high-pressure engine oil system High-pressured oil pump is used - HPOP Pump used to pressurize the fuel within the fuel injector for proper atomization and direct injection into the cylinders

In Summary… Fuel injector "spool valve" is trying to move back and forth inside the injector In a 6.0L this is achieved with two 48v coils on each end of the spool valve while trying to overcome anywhere from 500-4000 psi oil pressures being generated Spool valve bore needs to be contaminate free and unrestricted for proper fuel injector operation Carbon contaminates, Varnish build up, or Wear will cause the spool valve to stick, especially when the oil is cold & thicker and isn't flowing as easily, even with thinner grade oils

Fuel Management System There are injector stiction issues on Ford 6.0L & 7.3L PowerStrokes with the HEUI fuel injection system. (Hydraulic Electronic Unit Injection)

What is HEUI fuel injection? Questions What is HEUI fuel injection? An engine oil pressurized fuel injection system Uses crankcase motor oil to pressurize the fuel inside the fuel injector via a separate high-pressure oil pump within the engine. High-pressure oil pump puts out anywhere from 500-4000psi oil pressure  Very hard on any motor oil, synthetic or conventional

Questions What are the symptoms of fuel injector stiction? Romping uneven engine idle Hard starting & Cylinder misfiring Unable to accelerate until the engine warms up Loss of performance means lower MPG

What causes fuel injector stiction? Questions What causes fuel injector stiction? An inability for the high-pressurized motor oil to flow correctly through the fuel injector "stiction" comes from sticking spool valves inside the fuel injector’s high-pressure oil circuitry The spool valve allows oil pressure in and out of the fuel injector It is controlled by two 48v coils inside the injector and moves side to side back and forth. When ON, it allows oil pressure to push the fuel into the cylinders. When OFF, it bypasses the oil back to the crankcase.

Questions What causes these spool valves to stick? Worn spool valves and or engine oil contaminates within the spool valve bore or orifice and varnish build up Spool valve only moves 0.43mm in a 6.0L PowerStroke Less than a half a millimeter for high-pressurized motor oil to flow

Answer What can be done about the spool valves sticking? Add Archoil AR9100 into your motor oil -This will liquefy all deposits in the fluid system free up contaminated injector spool valves -Injector stiction symptoms completely disappear, even at -20F -Normally happens shortly after application -If spool valves are severely worn or injectors have worn fuel delivery pintles or nozzles, it usually indicates injector needs replacing AR9100 has a high 90%+ success rate, but it also does much more.

For more information go to Archoil.com Contributing Technician Harry Johnson Mercedes Benz USA master certified diagnostic technician ASE master and L1 certified advanced engine performance specialist WA State certified diesel emission specialist For more information go to Archoil.com