The Actron CP9190 scan tool is a valuable tool for diagnosing engine problems, especially when performing a Key On Engine Off (KOEO) test. This test allows you to retrieve diagnostic trouble codes (DTCs) and sensor data without running the engine, providing insights into potential issues. This article will explore the use of an Actron CP9190 scan tool in diagnosing a Ford engine that exhibits specific symptoms during a KOEO test.
Understanding the Problem: Symptoms and Initial Diagnosis
The subject vehicle, a Ford truck, starts and runs but the timing remains fixed at 10 degrees Before Top Center (BTC) and doesn’t advance. The Powertrain Control Module (PCM), also known as the Engine Control Module (ECM), cannot control engine RPM. Initial attempts to read codes using Innova 3145 Ford code readers resulted in the fuel pumps activating briefly, followed by a blank display. However, the Innova readers successfully retrieved codes when the PCM was bench tested.
Connecting the Actron CP9190 scan tool reveals several DTCs in high-speed data mode, but attempting the Engine On/Engine Running (EOER) test, specifically the RPM control portion, causes the engine to stall. The following codes were retrieved during the KOEO test:
- 111: System Pass (No faults detected during KOEO)
- 512: PCM/ECA (Keep Alive Memory) Error
- 412: Cannot Control RPM During Self-Test (High RPM Check)
- 116: Engine Coolant Temperature Out Of Range During Self-Test
- 172: HO2S (Heated Oxygen Sensor) System Lean (Bank 1)
- 411: Cannot Control RPM During Self-Test (Low RPM Check)
Analyzing Sensor Data at Idle and Under Light Throttle
The Actron CP9190 also provides sensor data snapshots. At idle, the following readings were observed:
Key observations at idle include a low Engine Coolant Temperature (ECT) reading of 106°F, closed loop status indicating an open loop fuel control strategy, and a lean oxygen sensor reading (O2SEN 1) of 0.00V.
Revving the engine slightly resulted in these readings:
While the Engine Speed (ENGINE SPD) increased to 1772 RPM and the Engine Vacuum (EVP) rose slightly, the oxygen sensor remained lean and the loop status remained open. The Electronic Vacuum Regulator (EVR) shows a significant increase in duty cycle, indicating an attempt to adjust engine vacuum.
Interpreting the Results and Potential Causes
The retrieved DTCs and sensor data point to several potential issues. The inability to control RPM during the self-test (codes 411 and 412) suggests a problem with the PCM’s ability to command changes in engine speed, potentially due to faulty wiring, a malfunctioning idle air control valve (IAC), or a problem within the PCM itself. The KAM error (code 512) indicates a potential issue with the PCM’s memory, which could be related to a power supply problem or a faulty PCM. The lean condition (code 172) could be caused by a vacuum leak, a faulty fuel pump, a clogged fuel filter, or a malfunctioning oxygen sensor. The out-of-range coolant temperature (code 116) during the self-test could indicate a faulty coolant temperature sensor or a problem with the wiring.
Conclusion: Next Steps in Diagnosis
The Actron CP9190 scan tool’s KOEO test and sensor data provide valuable information for diagnosing the Ford engine’s issues. Further diagnostic steps should include:
- Verifying the integrity of the wiring and connectors related to the PCM, IAC valve, and coolant temperature sensor.
- Testing the functionality of the IAC valve and coolant temperature sensor.
- Inspecting for vacuum leaks.
- Checking fuel pressure and fuel filter condition.
- Considering the possibility of a faulty PCM. Further testing with a dedicated PCM diagnostic tool may be necessary.
