Help troubleshooting engine issue during approach / landing

[FredG]

Hello to you all,

I have been having issues with my M20J the past few weeks whilst coming in to land. Following eventless flights, after setting the plane for landing on reduced power, I have a vibration appearing when adding power. It happened twice on the circuit pattern, and once on the runway after landing, adding power to taxi back.

I don't have a modern engine monitor, just the basic stuff and all seemed in the green.

I have not been able to replicate the issue on the ground from starting up the engine. It seems to happen after a flight out and back, engine hot somehow.

I recently got a G5+GFC500 setup installed during the annual. The issue appeared after that and not sure if there is a coincidence.

Prior to take off, all engine check are fine.

Any pointers?

Thanks for your help.

F.

[warren.huisman]

What are your power setting which have the vibration?


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[FredG]

I would say it starts at 1800rpm. within the yellow arc but doesn't stop going above.

[Red Leader]

Since this is a recent development, your question should focus on "what has changed recently". Did you notice the issue just after an annual? Did someone work on your engine recently? Get the oil changed? Update something in the engine bay? It is possible that nothing has changed recently and that this is just a new development, but I would start by answering the aforementioned questions.  Who knows, it could be something as simple as the temperatures in which you fly because of the changing seasons. Once all this is ruled-out, you could look at the fuel system, magneto timing or change in flying habits. 

[N204TA]

I had something similar happen to me.  Turned out to be a clogged fuel injector. 
 

 

Edited June 20, 2024 by N204TA

[FredG]

8 hours ago, N204TA said:

I had something similar happen to me.  Turned out to be a clogged fuel injector. 
 

 

Thank you for your reply. Was that also in the approach / landing phases with issu when you added power back?

[Fritz1]

maybe idle just a tad rich and temps getting hot, try leaving mixture at cruise setting for approach, also reduces plug fouling, on the ground lean mixture as much as possible so engine just does not die during taxi

[LANCECASPER]

11 hours ago, N204TA said:

I had something similar happen to me.  Turned out to be a clogged fuel injector. 
 

 

Which often is a maintenance induced failure during the annual. This happened to me a few years ago. I noticed that the mechanic took the injectors apart and was cleaning them in the Hoppes solvent that had been used over and over.   On run up we had a rough running engine. With the engine monitor we figured out which cylinder it was and pulled that injector and cleaned it with new Hoppes solvent that I had, That solved it. 

[Yetti]

Start with the plugs.   Think about leaning.   Mine is land, stable rolling, lean, pop the door.

[N204TA]

6 hours ago, FredG said:

Thank you for your reply. Was that also in the approach / landing phases with issu when you added power back?

It was on the approach at the end of a three-hour leg of a long trip.  It actually started running rough when I pushed the mixture rich with the throttle back.  I pulled the mixture back until the engine ran smoothly but it got rough again when I needed a little more power. 

[Yetti]

2 hours ago, N204TA said:

It was on the approach at the end of a three-hour leg of a long trip.  It actually started running rough when I pushed the mixture rich with the throttle back.  I pulled the mixture back until the engine ran smoothly but it got rough again when I needed a little more power. 

I don't touch the mixture from cruise to landing.  Just leave it set.    Looks like you have your answer you over riched it.   if you need more power then add throttle.

[N204TA]

1 hour ago, Yetti said:

I don't touch the mixture from cruise to landing.  Just leave it set.    Looks like you have your answer you over riched it.   if you need more power then add throttle.

I'm glad that works for you.  I like to follow the Before Landing Checklist in the POH and "Mixture Control - FULL RICH" has never been a problem in 29 years with this airplane except for that one flight.  I pulled the #1 fuel injector and it was completely plugged up with blue dye residue.  

[Shadrach]

1 hour ago, N204TA said:

I'm glad that works for you.  I like to follow the Before Landing Checklist in the POH and "Mixture Control - FULL RICH" has never been a problem in 29 years with this airplane except for that one flight.  I pulled the #1 fuel injector and it was completely plugged up with blue dye residue.  

Completely plugged up? If that was the case, that cylinder would miss. Was it the inlet screen that was clogged? Blue dye takes a while to accumulate. If the injector intake screen was completely blocked, then that injector will mot atomize furl optimally. Yetti was just trying to help. Firewalling the mixture on a hot, high DA day isn’t very considerate of conditions. 

[Shadrach]

On 6/16/2024 at 6:51 AM, FredG said:

I would say it starts at 1800rpm. within the yellow arc but doesn't stop going above.

I would have a maintenance professional carefully inspect the motor mount.

[FredG]

4 hours ago, Shadrach said:

I would have a maintenance professional carefully inspect the motor mount.

engine mount issue, wouldn't that be replicable on the ground during power up checks relatively easily?

[Shadrach]

7 hours ago, FredG said:

engine mount issue, wouldn't that be replicable on the ground during power up checks relatively easily?

I must have misread your first post. I thought it was reproducible on the ground and in the air, but dependent on advancing throttle from a very low power.

[N201MKTurbo]

I usually tell people that the fuel divider isn't their problem because it doesn't really do anything. Except at very low fuel flows, which is where your problem is. It wouldn't hurt to pull the piston out and inspect the diaphragm, piston and spring. Make sure the piston slides smoothly, the diaphragm doesn't have any holes and there is no crud in it.

[PT20J]

23 hours ago, LANCECASPER said:

Which often is a maintenance induced failure during the annual. This happened to me a few years ago. I noticed that the mechanic took the injectors apart and was cleaning them in the Hoppes solvent that had been used over and over.   On run up we had a rough running engine. With the engine monitor we figured out which cylinder it was and pulled that injector and cleaned it with new Hoppes solvent that I had, That solved it. 

Did he blow them out with an air hose afterwards? If there are deposits, the solvent can soften them but they may remain within the nozzle and clog it unless blown out. I found this out once when I forgot to blow them out. Also, some manuals (AvStar) recommend rinsing with hot water after soaking in solvent. This works with acetone or MEK, but Hoppes reacts with water and makes a white goo.

[Yetti]

18 hours ago, N204TA said:

I'm glad that works for you.  I like to follow the Before Landing Checklist in the POH and "Mixture Control - FULL RICH" has never been a problem in 29 years with this airplane except for that one flight.  I pulled the #1 fuel injector and it was completely plugged up with blue dye residue.  

Most people here miss the flaps as required in the Operators Manual.    That said I was taught this by my transition instructor.   Who is a Mooney Safety Instructor,  IA/AP, Mooney E Owner with same engine.      I also don't follow the Hot start procedure in the Operators Manual because it will flood the engine.  Shut down at 1000-1100 with mixture.   Just Crank to start and add mixture when pops. Is the way.

That's quite a feat.   Baby jar test should be your first step.