Use this procedure in order to troubleshoot an engine overspeed that happens immediately after engine starting. Also refer to Troubleshooting, "Engine Overspeeds" in order to troubleshoot an engine overspeed that does not happen at engine starting.
- Throttle signal
- Turbocharger oil seal
- Starting aid (if applicable)
Refer to the diagnostic procedure Troubleshooting, "Engine Misfires, Runs Rough or Is Unstable".
Connect AVSpare Electronic Technician (ET) to the service tool connector. Check for active diagnostic codes and event codes. Look for active diagnostic codes that are related to the throttle signal. Resolve any problems that are related to active diagnostic codes before continuing with this procedure.
Ensure that the application's throttle is set to the low idle position before cranking the engine. Monitor the status of the "Throttle Position" parameter on Cat ET while you crank the engine. The low idle setting for the "Throttle Position" parameter will be 0 percent. Correct any problems that are discovered. Refer to Troubleshooting, "Speed Control - Test" for information that is related to troubleshooting the throttle signal.
A turbocharger oil seal that is leaking can provide fuel to an engine that would otherwise not be fueled. The oil is passed into the inlet air supply and to the engine. The engine oil provides the engine with combustible fuel.
Remove the inlet air piping from each of the turbocharger compressor housings. Visually inspect the internal portion of each of the compressor housings for engine oil.
Check for proper operation of the starting aid(s).
Check for hydrocarbons in the surrounding atmosphere. Do not operate the engine in an environment with hydrocarbons in the surrounding atmosphere.