Engine rough and dies at idle.

[Guitarmaster]

It never fails to amaze me how you can put the plane away working perfectly fine and come out a couple weeks later to find a problem.

I pulled Riley out of the hanger got her all set up and ready to go to work. I tried to start her up and.... it was a little harder to start than normal. After she was running, she was idling like a Chevy big block with a Monster cam. Eventually it just died at idle.

She seemed to run fine once I got the power up and the mag check looks good. Although I have not pulled the trace from the EDM, nothing displayed showed anything out of the ordinary.

Needless to say, I didn't fly to work tonight.

She seems to be running really really rich. When I pull the mixture control all the way back, she still wants to run a little bit. This is very unusual behavior to say the least.

Although I'm a little pissed that I have this problem, I'm very thankful that it happened on the ground; whatever it happens to be!

Ideas?

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[Marauder]

It never fails to amaze me how you can put the plane away working perfectly fine and come out a couple weeks later to find a problem.
I pulled Riley out of the hanger got her all set up and ready to go to work. I tried to start her up and.... it was a little harder to start than normal. After she was running, she was idling like a Chevy big block with a Monster cam. Eventually it just died at idle.
She seemed to run fine once I got the power up and the mag check looks good. Although I have not pulled the trace from the EDM, nothing displayed showed anything out of the ordinary.
Needless to say, I didn't fly to work tonight.
She seems to be running really really rich. When I pull the mixture control all the way back, she still wants to run a little bit. This is very unusual behavior to say the least.
Although I'm a little pissed that I have this problem, I'm very thankful that it happened on the ground; whatever it happens to be!
Ideas?
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Must be a conspiracy with 1975 F models. You described almost perfectly my experiences with Vic over the past few weeks. She was getting harder to start, failed a mag check and even did the "dieseling" you described.

My first diagnosis was done by SavvyAnalyis and Paul found an issue with both plugs on the #2 cylinder. I replaced both plugs with a set of known good ones. The problem got better. I did a Gami and mag check and sent the results in. Paul saw an issue with a mag timing which later showed one mag was timed a bit early.

Earlier this week I had one run on experience like you described but the mag checks were fine.

Not sure what is your issue but these sisters must have found out how to communicate.

One thing you do want to make sure you aren't experiencing is "morning sickness" -- aka a stuck exhaust valve. Let us know what the findings are. BTW -- not promoting Savvy Analysis but since I know mostly what the buttons do on the inside and less about the moving stuff upfront, it is nice having someone look over the data who has a better understanding.


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[Mooneymite]

Morning sickness was the first thing I thought of, too.

Have you ever had the valve wobble check done?  How many hours on your engine?

(Obviously couldn't  be morning sickness since it happened in the afternoon!  )

 

Edited November 13, 2016 by Mooneymite

[Guitarmaster]

26 minutes ago, Mooneymite said:

Morning sickness was the first thing I thought of, too.

Have you ever had the valve wobble check done?  How many hours on your engine?

(Obviously couldn't  be morning sickness since it happened in the afternoon!  )

 

I thought about a stuck exhaust valve, but all the EGT and CHT were very close to each other.  I would think a stuck valve would give an odd indication on the offending cylinder.

I have not had the wobble check done.  The engine has ~170 hours on it.  

Years ago, I flew an Aztec that had this issue.  The spider was the issue there.  

The problem "feels" like a fueling problem.  The fact that I had to lean it almost to the stop to get to run smooth-ish seems to point to too much fuel.

Chris,

I am signed up with Savvy and am going to send the information to them as soon as I get home from this trip. 
Agreed. I am beginning to think our "sisters" share a common brain (and demon).  Do you have a chant and dance for this problem??

[Guitarmaster]

28 minutes ago, rogerl said:

First thing I'd check regarding the dieseling issue is the fuel flow divider.  There is a little spring and ball in there that can weaken and allow flow when it shouldn't.  This was my problem with an io360 I used to run.  Discovered after, of course, I had sprung for a 1 amu servo rebuild that didn't fix the problem.

Thanks!  This will be the starting point after discussing it with my IA.  

[Danb]

From the location accountant ..what's dieseling..

im the mechanical illiterate 

[takair]

Does the situation get better as the engine warms up or is it constant with temperature?

[Guitarmaster]

6 minutes ago, Danb said:

From the location accountant ..what's dieseling..

im the mechanical illiterate 

This is where the fuel "compression ignites."  You see it with high compression engines or sometimes, bad fuel.  You don't see it in the new cars because fuel is cut off electronically, but the older cars would continue to pump fuel into the cylinders and a hot spot combined with high compression would ignite the fuel.  Since a diesel is a compression ignition engine, the phenomenon got the term, "dieseling."

[Guitarmaster]

10 minutes ago, takair said:

Does the situation get better as the engine warms up or is it constant with temperature?

No.  The cylinders warmed up to about 200F with no difference in the symptoms.

[takair]

As others mentioned, flow decider comes to mind.  I had my fuel servo (throttle body) have an issue years ago.  Hard starts and rough idle until it warmed up.  Had an internal issue.  That said, I wonder if it could be as simple as a plugged injector.  One cylinder getting almost no fuel while the others would be rich. Analyzer would show this. Hate when these gremlins show up unannounced.  

[Marauder]

I thought about a stuck exhaust valve, but all the EGT and CHT were very close to each other.  I would think a stuck valve would give an odd indication on the offending cylinder.

I have not had the wobble check done.  The engine has ~170 hours on it.  

Years ago, I flew an Aztec that had this issue.  The spider was the issue there.  

The problem "feels" like a fueling problem.  The fact that I had to lean it almost to the stop to get to run smooth-ish seems to point to too much fuel.

Chris,

I am signed up with Savvy and am going to send the information to them as soon as I get home from this trip. 
Agreed. I am beginning to think our "sisters" share a common brain (and demon).  Do you have a chant and dance for this problem??

The chant I used on this one was easy. I chanted "1.2, 1.2, 1.2 AMU" as I danced around the ATM.


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[Danb]

42 minutes ago, Marauder said:

 

The chant I used on this one was easy. I chanted "1.2, 1.2, 1.2 AMU" as I danced around the ATM.


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Im sure with tears in your little eyes

[Brian Scranton]

I had the same happen to me. Did you do the ol' "clean those fouling plugs" by bringing her up to high rpm 2000ish, lean until roughness, let it sit there for a minute, watch the temps get nice and hot, enrichen, pull power back, repeat? You could just have some carbon scoring or gunk on the plugs. Also, simple enough to pull, gap and clean the plugs up too if you have an A&P who can guide you though it. Took me about an hour. 

[Dham]

Interesting. My 67F had all 4 cylinders replaced and fuel servo in aug. still running mineral oil was running hot on climb out but cool down in level light thought it was normal so I was looking forward to oil change. Last week took off and noticed what I call a little stutter and was going to land at nearby airport but seem to get better so I continued 30 minute flight (to get new transponder). When I picked plane up had same issue at 3000 temps seemed fine. As I was getting ready for a 2 mile final the engine quit. 2 mile final in a mooney not hard but not fun. Give my running hot on climb out thought it was mineral oil and hot day but not sure it may just be running lean. Hope to know something soon. I do have JPI 830 I hope will help take some guessing out. 

[Yetti]

Hmm My F too.  cleaned the plugs. Found a lead ball in the gap of one of them.  Problem persists.  Will be seeking professional help next week.

[N601RX]

What the original poster posted sounds like the sniffle valve may be gummed up. 

[Marauder]

Hmm My F too.  cleaned the plugs. Found a lead ball in the gap of one of them.  Problem persists.  Will be seeking professional help next week.

Definitely a 75 F conspiracy going on.


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[macosxuser]

Sounds like a fueling issue to me. I would second the Flow Divider check to start.

[Guitarmaster]

Definitely a 75 F conspiracy going on.


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I think the Russians hacked the F models.

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[Guitarmaster]

***SOLVED!!***

After consulting with my IA, I took a piece of .032 wire and routed around in the vent hole on the flow divider.  I also did a cleansing dance and chant prior to the aforementioned procedure.  Voilà!  Engine runs nice and smooth.  Appears that the vent hole was plugged... or the demon was exorcised.  Either way....

The plan is to see if it comes back and if so, replace the fuel divider.

Total cost so far... Zero AMU!  Here's hoping it stays that way!

[1964-M20E]

On 11/13/2016 at 9:18 AM, Danb said:

From the location accountant ..what's dieseling..

im the mechanical illiterate 

Dieseling is when a gasoline engine (which require spark to ignite the fuel i.e ignition system either a magneto or electronic or other) continues to run after the ignition source has been terminated.  This used to be real prevalent in car engines before fuel injection.  Dieseling is not typically in aircraft engines since we remove the fuel source (pull the red knob to full lean) to shut the engine down before turning off the magnetos.

A diesel engine is a compression ignited engine.  It uses the heat of compression to ignite the fuel air mixture therefore it does not need a spark so that is why the term dieseling is used.

 

 

[Marauder]

***SOLVED!!***

After consulting with my IA, I took a piece of .032 wire and routed around in the vent hole on the flow divider.  I also did a cleansing dance and chant prior to the aforementioned procedure.  Voilà!  Engine runs nice and smooth.  Appears that the vent hole was plugged... or the demon was exorcised.  Either way....
The plan is to see if it comes back and if so, replace the fuel divider.

Total cost so far... Zero AMU!  Here's hoping it stays that way!

How about a picture?


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[N201MKTurbo]

On 11/13/2016 at 10:10 AM, Dham said:

Interesting. My 67F had all 4 cylinders replaced and fuel servo in aug. still running mineral oil was running hot on climb out but cool down in level light thought it was normal so I was looking forward to oil change. Last week took off and noticed what I call a little stutter and was going to land at nearby airport but seem to get better so I continued 30 minute flight (to get new transponder). When I picked plane up had same issue at 3000 temps seemed fine. As I was getting ready for a 2 mile final the engine quit. 2 mile final in a mooney not hard but not fun. Give my running hot on climb out thought it was mineral oil and hot day but not sure it may just be running lean. Hope to know something soon. I do have JPI 830 I hope will help take some guessing out. 

Glad to see you are taking care of my old friend! Hope you get the engine straightened out soon.

[Guitarmaster]

How about a picture?


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Like this?




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[Yetti]

Is that routed around or rooted around?