CM850 Electronic Control System – FAULT CODE 1718

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Overview

Circuit SMALL | MEDIUM | LARGE

Circuit Description

An algorithm in the ECM calibration monitors engine speed as each injector fires while the engine is at idle. If a cylinder has high or low contribution to engine speed, this fault will become active. The intention of this fault is to assist in troubleshooting performance complaints such as engine misfire and low power.

Component Location

The ECM is located on the intake side of the engine. 100-002 (Engine Diagrams) in section E for a detailed component location view.

Shop Talk

If Fault Code 1718 is inactive in the ECM memory and there is no complaint such as “low power” or “engine misfire”, it is possible that an intermittent event such as air entering the fuel system following a filter change caused the fault. Inactive counts of Fault Code 1718 should be disregarded unless other performance symptoms are present. The engine coolant temperature must be greater than 160°F before this diagnostic will run.

Causes of cylinder misfire can include:

• Valve lash out of specification (compare actual valve lash to reset limits)
• Cylinder failure (check for high blowby when the engine is loaded)
• Valve failure or valve held open (listen for intake valve “chirping”
  noise in the intake)
• Cylinder head or gasket failure (look for signs of oil, coolant, or casting flash in the intake or exhaust passages)
• Extreme camshaft wear (inspect the camshaft lobes for wear)
• Extra, missing, or damaged sealing washer under an injector
• Injector failures (“swap” injectors to see if the problem “follows”
  the indicated injector).

On-Board Diagnostic (OBD) Information:

• The ECM illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails
• The ECM turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. The MIL lamp and fault code can also be cleared using the INSITE™ service tool
• The fault code will be cleared from the memory after 40 consecutive drive cycles when the diagnostic runs and passes.

Refer to Troubleshooting Fault Code t05-1718