Rough running immediately after annual ... Coincidence?

[VetRepp]

I just  got my plane back from Annual, It ran perfectly beforehand and no squawks going in.

(A little history ...  Converted the engine to Ovation 3 (310hp) at last annual – Only engine change required is increasing prop governor speed and increasing fuel flow.  Anyway as I said it ran perfectly for a whole year.)

Nothing was found to be an issue during annual except the Spark plugs were apparently out of tolerance and replaced. They ran engine afterwards and everything was OK.

Went down today to fly it for the first time since signed off a couple days ago. Engine running rough. #1 cylinder not making power. They checked it out and thought fuel injector nozzle to cylinder #1 was getting plugged (as part of the annual they ultrasonically cleaned all injectors). Recleaned the injector put back together. The issue then changed to Cylinder #2, Repeated the process, Recleaned put back together. The issue change to Cylinder #3, Repeated the process, Recleaned put back together. The issue changed back to Cylinder #1, - They tried with the old plugs back in; They rechecked magneto timing  - no change. (BTW The Magneto is hundreds of hours away from it’s 500hr overhaul)

They disconnected and checked the fuel going to each cylinder using the fuel pump and reported has debris?? They think a gasket or something might be disintegrating in the Fuel manifold that sits atop the engine. That’s as far as they got today. (BTW The spark plugs were changed from Champion fine wire to Tempest, but they’re convinced it’s the fuel side of combustion that’s causing the problem.)

 

Questions:

1)      Is this just incredibly bad and coincidental timing – (first time check out after annual – running fine beforehand) or could it be related to annual. To my knowledge the only part of the annual that involves the fuel system is cleaning the fuel screens and Injectors.

2)      Does it make sense to jump from Cylinder to cylinder?

3)      Any other thoughts as to cause, or what’s gone on would be appreciated

 

Thanks in advance

Roger

 

 

[carusoam]

Well...

Surely,  something changed...

Got any JPI data to share?

The section of data that is most interesting is the run-up...  if you are familiar with data collection... run-ups take a while to get good data...  engine monitors can be set up better than when they get purchased (sometimes)...

Debris on a fuel screen... that can’t be good...  we would want to find out where that is coming from...

There are often small pieces of rubber hoses used in fuel lines near the engine.... it could be an inner lining of the hose sluffing off...

Anything unknown getting cleaned out of my engine... gets saved, ID’d and catalogued... until I know what it is and where it comes from... and if he has any brothers I need to know about... 

PP thoughts only, not a mechanic...

Best regards,

-a-

[VetRepp]

I don't unfortunately,

It's a 2006 w/ G1000, The engine monitor was how we could tell where to start since #1 cylinder did not rise.

I had just started it and it ran rough from the beginning (it wasn't just a first start roughness that smoothes out in 30 sec) - So I taxiied it nervously over to the A&P cause I wanted him to witness it , I didn't dare increase RPM over 1000.

I don't know how to harvest data from the my G1000 or if it's even possible with that year software setup? But prior to annual - No problem.

Thanks Roger

[carusoam]

Harvesting data from a G1000 adds to the challenges... Some didn’t save any data... back in the day...

Got any screen shots?

See if anyone has answers, then go Directly to the big guns... Paul K. and Clarence...

Best regards,

-a-

[Shadrach]

6 minutes ago, VetRepp said:

I don't unfortunately,

It's a 2006 w/ G1000, The engine monitor was how we could tell where to start since #1 cylinder did not rise.

I had just started it and it ran rough from the beginning (it wasn't just a first start roughness that smoothes out in 30 sec) - So I taxiied it nervously over to the A&P cause I wanted him to witness it , I didn't dare increase RPM over 1000.

I don't know how to harvest data from the my G1000 or if it's even possible with that year software setup? But prior to annual - No problem.

Thanks Roger

Probably need more than just data from idle. Did you do a Mag check?  What do you mean cyl 1 did not rise? Are you saying it was cold? Are you saying EGT did not rise during mag check. Fuel, air or spark issues can cause a cylinder(s) to run rough. Record what is happened during ground run and mag check. An engine monitor can tell you more than Just which cylinder is rough.

Edited June 20, 2020 by Shadrach

[StevenL757]

I tend to agree.  Ran into this to a very small degree on my first ground run after annual last month.  Cyl. 2 EGT was around 400-450, whereas the other five were normal.  Noticeable amount of vibration and toughness.  Removed and cleaned a tiny piece of crap from the #2 injector, reinstalled, ran again and all was normal.

[ArtVandelay]

If you drain fuel from the gasolator do you see any debris?
You didn’t ever used auto (ethanol based) gas I hope.
They had problems with electric boost pump causing this and added screen after the pump, but I thought this was only for older models.

[Danb]

Roger if you did the waas upgrade you should be able to download the engine data, good luck with your issues.

[Guest]

I’ve never heard of spark plug issues moving from one cylinder to another.  More likely an issue with contaminated tools used during fuel nozzle work.  The socket used to install the tools should be swabbed clean or be thrown in the ultrasonic cleaner before use.  Other wise why pull the nozzles?

Clarence

[HRM]

9 hours ago, VetRepp said:

...or what’s gone on would be appreciated

[GeeBee]

4 hours ago, HRM said:

Yes, the Waddinton effect writ large

 

[Shadrach]

4 hours ago, M20Doc said:

I’ve never heard of spark plug issues moving from one cylinder to another.  More likely an issue with contaminated tools used during fuel nozzle work.  The socket used to install the tools should be swabbed clean or be thrown in the ultrasonic cleaner before use.  Other wise why pull the nozzles?

Clarence

The bigger question is why pull the nozzles at all unless it’s been confirmed that the symptoms indicate an injector problem.

[Bravoman]

If I am not having any with issue with fuel flow, or anything injector related I always tell them not to touch the injectors during the annual. I had a similar experience after my injectors were cleaned some years back. My experience has been that you’re asking for trouble when the injectors are prophylactically serviced at annual.

[ArtVandelay]

If I am not having any with issue with fuel flow, or anything injector related I always tell them not to touch the injectors during the annual. I had a similar experience after my injectors were cleaned some years back. My experience has been that you’re asking for trouble when the injectors are prophylactically serviced at annual.

I thought that’s a requirement? At least it’s a line item in the Mooney inspection form.

[HRM]

1 hour ago, ArtVandelay said:

I thought that’s a requirement? At least it’s a line item in the Mooney inspection form.

I think it's up to the IA, but I always agree with an "if it ain't broke, don't fix it" maintenance strategy.

[bradp]

Seems like your cylinder problem might be tracking with the random order in which your nozzles are being placed back on?

Another thing to consider is if a nozzle was damaged during removal.  Ie the screen is pinched or someone used a wire or pick in there is a no no. Inspect nozzles carefully and baby bottle test.