High EGT's and low RPM

Jon Tensfeldt wrote:

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

It has 240 hours with the filter being changed in the 120 hr. range.

Update - changed the fine filter this afternoon and took the plane up in the pattern.  So far all is good.  If anything bad happens I will let you know.  Otherwise assume that changing the filter solved the problem.  

Thanks for everyone who provided feedback.  This really helped to guide my efforts.

Well, so much for that.  I took it up again today and it started out fine but soon went back to the same symptoms.  EGT's were all creeping up and the RPM's started to fall.  I landed and checked the course filter and found a little amount of materials but not nearly enough to cause an issue.  I added fuel, so it should have eliminated that being an issue.  Took it up again with no change.

So I am back to square one again.  All temps and the fuel pressure were normal.  It definitely helped to have both pumps on as I usually fly with only one.  But the RPM's were lower than normal.  Even with the throttle full in the engine struggled to get to 5000 RPM.  But it would surge and go up then come back down.

Not sure where to go next.  I can check the fuel lines from the header tank, but while the course filter was off I let fuel run to possibly clean things out a bit.  It seemed to have plenty of fuel flow.  But it is hard to tell.  

The Kitfox has two tanks that feed to a header tank.  The header tank feeds to the course filter then to the pumps.  The fuel pressure gage is next then the fine filter.  After that it heads to the spider and the injectors.

Any other things to check?  

Would a clogged air cleaner cause this? What about a failing manifold pressure sensor?  What about the ambient temperature and pressure sensor?Is it thus possible that the engine “thinks” the air density is less than actual and thus delivers less fuel than optimum? Does this condition happen with one ECU switched off? If it runs normally on one ECU but not the other, would that point to a sensor failure?

geoffrey klestadt wrote:

Would a clogged air cleaner cause this? What about a failing manifold pressure sensor?  What about the ambient temperature and pressure sensor?Is it thus possible that the engine “thinks” the air density is less than actual and thus delivers less fuel than optimum? Does this condition happen with one ECU switched off? If it runs normally on one ECU but not the other, would that point to a sensor failure?

 

Thought about the clogged air cleaner, that should cause the mixture to richen up I think.  That is opposite of what I have.  As for failing sensors that might be possible, but all 4 cylinder EGT's are rising and RPMs are falling.  That is real and I can feel it. So there sure seems to be something wrong. 

I have not tried turning Lane A or B off. Worth a shot.  

My thoughts now are to completely drain the fuel and check all the lines in the collection tank upstream of the filters and pumps.  I can imagine something worked its way in to the main fuel line causing the fuel to be moving slow through that area.