Failure to pre-lean. [ See “LeanFind Procedure – Step-by-Step” in your Pilot’s Guide. ]

• Try leaning more slowly or more quickly. Do not pause during mixture adjustment. [ See “LeanFind Procedure – General Explanation” in your Pilot’s Guide. ]

• Check that if a bayonet or threaded adapter probe is installed, that it is screwed in tightly and the threads are clean in order to ground the factory probe. If adapter is not grounded well to engine, voltage will be applied to the adapter thermocouple junction and disrupt the EDM instrument.

•  Check that the EDM is grounded at the engine case(not in the instrument panel). Do not use panel ground, battery ground, or airframe ground. Airframe ground can vary from engine ground by 1/4v. This could cause the EDM to show too ‘High’ or ‘Low’,  EGT, CHT temps. Or show ‘Unsteady’ readings. If grounded to the panel, to check if this ground is OK, use a digital voltmeter to measure the difference between the EDM ground and the engine block ground. If the difference is greater than 0.5 volts with the alternator charging, then remove the EDM ground (black wire) from instrument panel and connect it directly to the engine block ground.

• Check for a bent or recessed pin on the rear P2 connector.

• Check crimps between probe and harness.