High EGT's and low RPM

Mr. RTX wrote:

I agree with Bill

IF you start to see a rise in fuel pressure, it is an indication the fuel filters are starting to become blocked. This is why the Fuel pressure sensor must be installed before the fine filter. 

Also, do you have a gascolator installed? This should trap most water before it gets to the fine filter which you can then drain out before each flight. 

Change your fuel filter and report back!

 

There was no obvious rise in fuel pressure. I have had that before if water hits the fuel filter. Since then I don't use Mogas in the plane without mixing it with Avgas.  The only change was the EGT's. But with that said, is still likely the fuel system.

You stated you had fuel contamination issues in the past.

The Fine mesh fuel filter has a bypass that will allow unfiltered fuel to go around the filter if it becomes too restrictive (blocked). IF too much-unfiltered fuel goes around the filter, it could cause issues with the injectors. 

The next step if your filter change doesn't fix the issue, is to swap the affected cylinder injectors from one cylinder to the other and see if the EGT issues follow that injector. IF it does then you need to clean the injector. 

Mr. RTX wrote:

You stated you had fuel contamination issues in the past.

The Fine mesh fuel filter has a bypass that will allow unfiltered fuel to go around the filter if it becomes too restrictive (blocked). IF too much-unfiltered fuel goes around the filter, it could cause issues with the injectors. 

The next step if your filter change doesn't fix the issue, is to swap the affected cylinder injectors from one cylinder to the other and see if the EGT issues follow that injector. IF it does then you need to clean the injector. 

 

That would be the right thing if only one EGT was affected.  In this case it was all of them, so changing the injector may not tell much. 

Hopefully it did not go through the bypass.  It does not seem like the pressure was high enough.  Hopefully it was just some slight blockage of the fine filter.  That is easily fixed.  

The bypass pressure on the fine filter check valve is .8 to 1.2 bar (11 psi to 17.4 PSI), so it needs quite a bit of pressure build-up before it goes into bypass.

Keep us posted on your results 

Hi Paul.  I was former Cirrus too. 

Just curious - how many hours do you have on this 912iS and have you ever changed the fine filter before?  Jon