mekanik
Senior Member
I had an International Work-Star with a Maxxfarce 10 in the shop yesterday. The complaint was after driving for a few minutes the check engine light would come on. I scanned it and it had two faults for injection pressure above desired and below desired pressure. My best guess is either the injection pressure sensor or the injection pressure regulator was failing. Since they are both prone to failure and can kill the engine on the road my advice was to replace both.
The pressure sensor is located under the valve cover. To remove the valve cover first remove the intake pipe from the cooler to disconnect the two connectors from the valve cover gasket, remove the wiper arms then the plastic trough below the windshield then the wiper transmission. Then get a box and put all the crap in the cab in the box. Then remove the plastic trim that holds the floor mat on both sides, remove both seats the storage box between the seats the fire extinguisher the throttle pedal the cup holder and the Allison Transmission shifter then roll the floor mat back and remove the plastic cover from the firewall, . You can now see the rear of the engine. Remove the two connectors at the left rear of the valve cover gasket and remove the cover bolts. Now lift the valve cover and tilt it just right and it will come out from the rear into the cab, this usually requires a bit of cursing. There it is the pressure sensor screwed into the side of the high pressure rail at the rear. Replace the sensor. If it had an engine brake I would replace the brake pressure sensor and control valve more $$$ replace the expensive valve cover with the wiring harness built into it $$$ again. six hours later its back together.
The Injection pressure regulator threads into the back of the high pressure pump between the intake manifold and air compressor. Get the special 1 3/8" socket with a slot machined in it to clear the connector and slip it under the copper main air line onto the IPR. Keep a magnet handy for when you drop it. once you get it in place with a 3/8" universal and extension thread it out. Carefully thread the new IPR in without dropping it, its a hydraulic valve and if you drop it it will land valve end first in the dirt. once the new one is in with a universal and extension there is no way to accurately torque it so I gave it my best guess. Next try to get both my Sasquatch size hands in there to plug the new IPR into the engine harness.
Once its all back together when you start it will run rough and miss and clatter for about ten minutes until the air is out of the high pressure system.
7.5 hours to replace a sensor and an actuator test drive the truck. I have always wondered do engineers really hate mechanics.
The pressure sensor is located under the valve cover. To remove the valve cover first remove the intake pipe from the cooler to disconnect the two connectors from the valve cover gasket, remove the wiper arms then the plastic trough below the windshield then the wiper transmission. Then get a box and put all the crap in the cab in the box. Then remove the plastic trim that holds the floor mat on both sides, remove both seats the storage box between the seats the fire extinguisher the throttle pedal the cup holder and the Allison Transmission shifter then roll the floor mat back and remove the plastic cover from the firewall, . You can now see the rear of the engine. Remove the two connectors at the left rear of the valve cover gasket and remove the cover bolts. Now lift the valve cover and tilt it just right and it will come out from the rear into the cab, this usually requires a bit of cursing. There it is the pressure sensor screwed into the side of the high pressure rail at the rear. Replace the sensor. If it had an engine brake I would replace the brake pressure sensor and control valve more $$$ replace the expensive valve cover with the wiring harness built into it $$$ again. six hours later its back together.
The Injection pressure regulator threads into the back of the high pressure pump between the intake manifold and air compressor. Get the special 1 3/8" socket with a slot machined in it to clear the connector and slip it under the copper main air line onto the IPR. Keep a magnet handy for when you drop it. once you get it in place with a 3/8" universal and extension thread it out. Carefully thread the new IPR in without dropping it, its a hydraulic valve and if you drop it it will land valve end first in the dirt. once the new one is in with a universal and extension there is no way to accurately torque it so I gave it my best guess. Next try to get both my Sasquatch size hands in there to plug the new IPR into the engine harness.
Once its all back together when you start it will run rough and miss and clatter for about ten minutes until the air is out of the high pressure system.
7.5 hours to replace a sensor and an actuator test drive the truck. I have always wondered do engineers really hate mechanics.