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Developed isolated high EGT on cylinder #3, reading 300 degrees higher than the other three EGT's ( 1650 compared to 1300-1400 on the others). Upon initial startup, #3 EGT immediately displays 600 degrees, before others register at all. Replacing with a new EGT probe has not altered the situation. Engine runs smoothly, with less than 100 hours on new cylinders. Normal CHT's. Is this an electronic issue? How to correct?
Thanks,
Kenneth Melvin
I have had same problem. Look for loose or separated connection. I use electric contact cleaner on the spades, then "pinch" them a bit and reconnect, cover with shrink tubing.
Regards,
Gary Brown
Definitely not the probe or its connections. Checked those before installing brand new probe from Advanced, with very tight spade connections. Same problem with new probe.
Thanks,
Kenneth
Somebody else recently indicated that the thermocouple wire harness was incorrectly labeled from the factory. Could it be that #3 is really displaying as number 1, 2, or 4? And that your problem is really with one of those cylinders? One way to test this theory is to take your heat gun to each exhaust stack and verify that the EGT increases for the cylinder you are heating up.
Gary Brown was absolutely correct. Although the spade connectors appeared bright, and were a tight fit on the new probe connectors, a thorough cleaning of the EFIS harness connectors with a scalpel blade has corrected the problem. Now with clean, tight spade connections, the EGT reading is normalized. If that had not worked, I think Noah's suggestion would be a good next step, along with switching #3 harness connectors to #1 EGT probe. However, reducing the resistance at the offending connectors has resolved the problem.
Thanks,
Kenneth
RV-9A, Hillsboro, Oregon
Another thing to watch out for is that the shrink wrap that covers the bodies of the terminals will "melt" if allowed to contact the shrink wrap of another terminal. This will lead to contact between the two terminals and wild indications even though the shrink wrap appears to be ok.
Try switching the probe wires between two cylinders, this will isolate the problem.