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base698

IO-360-A3B6 JPI EGT Reading Low

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Recently had a top overhaul.  During the incident that led up to the overhaul, #4 stopped reading entirely on the JPI-700.  Now after overhaul the #4 reads ~400 lower than all other cylinders for the EGT.   Occasionally it will warn of 500 degree difference.  CHTs for all cylinders are normal (310, 314, 330, 333) when in cruise enrichened higher than normal cruise with cowl flaps closed.  Have 10 hours since top overhaul.  Been very good about keeping CHT temps < 340.

One theory is that the probe went bad during the low oil pressure issue.  Anyone else have any other ideas?

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CHTs normal, one EGT out of sync indicates probe.  Probes go bad.  Cheap. Replace.

I have had several instances of poorly crimped connections causing either no EGT temp, erratic temps, or low temp.  Check the connections of the #4 EGT probe.  Might get lucky.

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I just had the same issue. Replaced the M111 probe from JPI with the Tempest one from Spruce. The Tempest probe is cheaper and appears much more robust.


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Typical method for knowing if the EGT sensor is to blame...

0) 400° F low, the sensor may be falling out... or not in the exhaust stream...

1) swap one for the next to see if the problem goes with the swap...

2) while you are doing this inspect the surface of the TC’s sheath(?)... If it is seriously corroded or missing bits, that is a good reason for a change...

3) test the sensor in boiling water and ice water.... 32°F And 212°F should be enough to know that the system is wired correctly and measuring properly...

4) See if they are all reading the same temp prior to start up...  gives a hint to grounding and other transient micro-voltage sources...

5) The exhaust stream is the most horrible environment for metals.  No surprise to have them fail...

6) How many hours are on your sensors? thousands and thousands?

Best regards,

-a-

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