I have an older M4 setup on a Porsche 968 racecar, and I've started seeing multiple sensor errors in the logs. Mostly ref and sync errors, but also air temp sensor errors. There isn't much storage in my M4, so I get less than 10 mins of logs at 5x / sec. In my most recent log, I'm seeing almost 3 minutes of errors on sync and ref in ~9 minutes of logs. Surprisingly the car seemed to run OK most of the session, but it was misfiring at times. Some observations after spending some time looking over the logs and also examining the car:
- The errors seem to come in clusters of 2-5 seconds, with sync and ref errors almost always at the same time.
- The errors seem to happen in all RPM ranges, but may be more frequent at higher RPM/load
- The air temp sensor, which is located in the airbox, is mostly giving readings all over the place, ranging from 0 deg C to 25 degrees (the actual air temp). Or giving an error in the logs (about 1 minute worth). The errors for this sensor are sometimes at the same time as the sync and ref, but not always.
- System voltage in the logs is consistently over 12V. I didn't see any evidence of low voltage or fluctuation like gauges going haywire, or low voltage on the voltmeter in the dash.
- I just looked at the car, and didn't see any obvious signs of wiring damage, loose grounds, etc.
It seems like a telltale sign that multiple sensors are giving issues at the same time. I assume these sensors need a voltage source (5 volts?), and perhaps that is flaky? Or a bad ground?
Thanks in advance for sharing any thoughts.
Scott
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