Troubleshooting: Cam Timing Nightmare

Jan. 1, 2020

2 min read

Dear Roy,

I have a 2000 Dodge Intrepid with a 2.7L engine that will run without the cam sensor signal, but if it should jump time a tooth, it will stop the injectors. When the water pump bearing fails, it does so silently. This extra limp-in mode for cam sensor failure is not in the service manual, nor is there anything about sensors being out of sync. There's also no information about this in Mitchell or on my Genisys scanner.

I couldn't find a TSB about it, and the local dealer's head mechanic had no knowledge of this either. I'm not the first to tackle this problem on this car. All this adds up to this problem being a real bastard to diagnose. Can you tell us more about this?

Thanks, Jake Payne Jr., Laurens, S.C.

Dear Mr. Payne,

This engine uses cam sensor input for ignition timing and sequential fuel injection. If the signal is missing, a code P1391 will typically set in memory. However, when cam timing is affected, the cam sensor is now sending a false signal to the PCM. This can result in a misfire or a no-start condition.

Many times, the act of just disconnecting the sensor will correct the misfire or allow the engine to start, typically with longer-than-normal cranking times. That is because the system has a limp-mode strategy that allows it to start after it finds the No. 1 cylinder, but it will operate as multi-port injection instead of sequential. Usually the engine's rpm is limited as well.

About the Author

Roy Ripple

Roy Ripple passed away in September 2021 at the age of 84. He was an automotive technician his entire life. He owned his own shop for years before his first and only venture into automotive journalism, with Motor Age magazine. In his youth, he was an avid drag racer and a good friend of Don Garlits. He raised four children, rode motorcycles, hunted deer, and loved to shoot trap. His son, Roy Dennis Ripple, now writes for Motor Age. You can see his work here.