Paul,    I had problems like that at one point and traced it down to shorts (to ground)  in the harness that has all the probes in it.
I ended up disassembling the whole harness and replacing a lot of the connectors.   ...and then being super careful that everything was well isolated.

On Aug 22, 2011, at 7:18 PM, paul miller wrote:

> Follow-up.  EGTs bouncing all over.   Before I do the lean test on the IO-550N I have another long term problem to solve.  All EGTs dance around sometimes 50 degrees or more.   The CHTs are solid.    I suppose I have to go back to the airport and turn everything on in order to see if it is electrical.  On my other airplane we physically separated the EGT wiring from the other wires with spacers (Insight monitor) and that made a difference.  I am sure the plug wires are running parallel to the EGT harness on the Legacy.   Sounds like some work but would like to hear more before I start the job.  Thanks Ron and Walter.
> On 2011-08-22, at 2:38 PM, Walter Atkinson wrote:
>
>> Ron has it right.  Since 100LL is a pretty good solvent, it's unusual to need to clean injectors unless there is a physical blockage.  The most common source of injector clogging is from shop rag lint from cleaning them!  A Gami Lean Test will tell you whether or not there is a problem with the injectors.
>>
>> Walter
>
>
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