Case IH F-1128-18 - ECU – Engine Control Unit (ECU): Turbocharger boost pressure is lower than expected

The ECU detects that the actual boost pressure is significantly lower than the expected target threshold, or the turbocharger speed signal period exceeds a defined limit, indicating an under-boost condition.

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1. 1

   Visually inspect the Electronic Variable Geometry Turbocharger (EVGT) actuation mechanism and linkage to verify it is correctly connected, not restricted, and not binding or blocked in any way.

2. 2

   Perform a charge air system leak check by inspecting turbocharger discharge piping, intercooler (charge air cooler) hoses, and intake manifold connections for sudden breaches, loose clamps, or split hoses that would allow boost pressure to escape.

3. 3

   Check the intake manifold pressure sensor (boost pressure sensor) and its wiring harness for damage, short circuits to the battery, or open loads.

4. 4

   Inspect the engine air filter to ensure it is not severely clogged, collapsed, or incorrectly remounted, which can restrict intake flow and prevent the turbo from building pressure.

1. 1

   Resolve Leaks

   If any leaks are found in the charge air cooler piping or hoses during the diagnostic phase, replace the damaged hoses and tighten all T-bolt clamps to spec.

2. 2

   Free or Replace EVGT Actuator

   If the EVGT linkage is sticking, attempt to free the mechanism. If the electronic actuator itself has failed internally, it must be replaced and recalibrated using the Case IH Electronic Service Tool (EST).

3. 3

   Test/Replace the Pressure Control Valve

   Check the wiring to the valve. If the wiring is intact but the valve's adaptation correction has drifted below the lower limit, replace the Pressure Control Valve.

4. 4

   Clear Codes and Test

   After repairs are made, use the Case IH EST to clear the ECU fault codes. Run the machine under a heavy load to verify that actual boost pressure now matches the ECU's expected target pressure.