2005 Focus PCM shutdown near 8000 RPM?

T

tb1999

New member
I've got a problem with my 2005 2.3L Duratec powered Focus.

When the revs get near 8000-8200 RPM, the PCM shuts down completely, (not just injectors) PATS light flashes and engine cannot be restarted until the igntion is cycled and PATS light proves out.

If I set rev limimter to 5500, it hits the rev limiter, kills the injectors, RPMS peak at around 7300 due to inretia, but the PCM remains operational.

When I set the rev limiter to 8000, the PCM shuts down. I've even tried pushing rev limiter up as high as 9100 RPM, but no change, it still cuts off completely near 8000.

I'm doing calibration changes with SCT Pro Racer software. There are no DTC stored. Since the PCM is powering off, I lose the datalogging buffer just before the shutdown event occurs, so I don't have any details about exact RPM or any other parameters.

I'm stumped and my racecar is almost useless unless this can be resolved. I don't want to convert to aftermarket ECU. Does anyone have a clue what might be going wrong?

BTW - I have already disconnected the alternator to rule out potential issues with odd voltage spikes, backfeed etc. No change.

You can see what I'm experiencing at the start of the race in this video. (@ ~0:45 mark)

The other power loss issue in this video was due to a bad O2 sensor. This has since been diagnosed and corrected, the shutdown problem still needs to be sorted out! :(
YouTube Video
ERROR: If you can see this, then YouTube is down or you don't have Flash installed.
 
Watch the tach readout closely on the video. It may just be me, but I am seeing rpm readings starting with 9 and 10, but just for a moment. If this is true and I am not seeing things, you may be getting rpm signal spikes that the ecu shuts down to try to prevent further damage. I had this exact issue with the rpm signal wire from my CAS to the ecu. We replaced the wires with static insulated wires and made sure they were routed away from any other electrical signals and the problem went away. We also were seeing spikes in the rpm data logging that confirmed what we were seeing on the tach and in the ecu behavior. We also used a newer version of the base software and everything is now smooth.

A buddy of mine had this exact issue with an Electromotive setup about 10 years ago and it was traced back to sender wire interference as well.

Just an idea.

Eric
 
23racer said:
Watch the tach readout closely on the video. It may just be me, but I am seeing rpm readings starting with 9 and 10, but just for a moment. If this is true and I am not seeing things, you may be getting rpm signal spikes that the ecu shuts down to try to prevent further damage. I had this exact issue with the rpm signal wire from my CAS to the ecu. We replaced the wires with static insulated wires and made sure they were routed away from any other electrical signals and the problem went away. We also were seeing spikes in the rpm data logging that confirmed what we were seeing on the tach and in the ecu behavior. We also used a newer version of the base software and everything is now smooth.

A buddy of mine had this exact issue with an Electromotive setup about 10 years ago and it was traced back to sender wire interference as well.

Just an idea.

Eric
Click to expand...


I can see it as well. The tach signal pegged more than once before the shutdown.
 
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