The best oil additive to cure your diesel’s stiction The pressure that the HEUI system operates on the oil side can be greater than 3000 psi, which is just terrible for the longevity of your oil, it breaks down the molecules much faster and creates foam.Īnother good reason to stay on top of your oil changes. Oil residue and foamy oil in the spool valve is the main issue with the HEUI system, and the best way to keep your injectors flowing well is to use an additive to clean them preventatively.įrequent oil changes are very important for your Powerstroke, remember that the injectors need oil pressure in order to operate and changing and checking your oil is the best way to ensure that the injector system stays operational and in good working condition. The bad part about this system is that it is affected by low quality fuel and oil, which is all too common and hard to avoid nowadays. The problem happens when the spool valve either has oil residue on it and becomes stuck, or when the engine oil becomes foamy to the point where the foam is creating a false injector pressure. This piston then converts the oil pressure into fuel pressure, and from there the fuel is injected into the cylinder at up to 4000psi. Instead of using a high pressure injection pump to pressurize the fuel in the injector body (like you’ll find in newer diesels) the HEUI system uses oil that has been pressurized very highly, sent directly into the injectors, to create the required fuel pressure.īasically, the oil pump pressurizes some of the engine oil, sends it to the HEUI system, which opens or closes a spool valve inside the injector, allowing the oil to push on the intensifier piston. Contrary to most modern common rail systems, the HEUI is now an outdated system that was introduced by Caterpillar way back in the 90’s.

The 6.0 and 7.3 Powerstrokes use hydraulically actuated electronically controlled unit injector (or HEUI) injectors. Stiction is unfortunately a very common problem with the fuel delivery system that these powerstrokes use, and can lead to serious issues with hard starts, rough idling, misfires and terrible overall driveability. In this guide, I wanted to cover an issue that many 6.0 and 7.3 powerstroke owners have run into, Injector stiction.

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