The joys of engine monitor diagnosis

[Bartman]

Back at n the spring we swapped a couple of injectors and had basically a GAMI spread of 0.0 to 0.2 for about 100 hours. It was great !!!

Over the past 3 flights I noticed that #3 now peaks before the rest. Last week's flight to work I noticed popping after I pulled the throttle to idle on short final. Today on return now #3 peaks waaaay before the rest and more popping on final. It was nice to be able to tell my A+P-IA what the problem was and which cylinder before we pulled the cowl. 

[bradp]

Injector?

[Bartman]

Nope. The intake tube was loose. I am no expert but if my logic is correct, this caused an intake leak and that cylinder was running leaner and peaking first. I'm not sure why that makes it pop and crack with the throttle at idle, but with the prop driving the engine on short final it is sucking thru the worn gasket making that cylinder even more lean percentage wise than it would be in cruise. Hopefully those with more knowledge will expound on this and deliver the whole story on the popping.

And this is not the first time this particular intake tube has been fond loose either. Same cylinder and tube about 4-5 years ago.  Bolts are tight, but you can shake and wiggle the tube with ease. 

He will remove this week and maybe we can get by one more time with a new gasket. My gut feeling is this tube has a bad flange either on the tube itself, the mounting flange or whatever it's called, or most likely both parts worn from all of the movement and I'll need some new parts this time. 

[gsxrpilot]

I can't imagine investing the kind of money we do in engines, and running them without an engine monitor. I'm not nearly experienced enough, nor wealthy enough to think about running without one. It was the first money I spent on my M20C which didn't have one. And upgrading from an EDM700 to EDM900 was the first money I spent on my 252.

@Bartman example here is just another reason for having one.

After the C I decided any Mooney I was thinking of purchasing would be marked down if the previous owner flew it without an engine monitor.

#dontflywithoutit

[1964-M20E]

Must be something about #3 I had the same issue earlier this year flying to Orlando.  Mine had come off completely but I guess the vacuum of the engine kept it in place until I pulled the power for landing.  With the engine monitor I knew exactly what cylinder was causing the problem didn't know what it was and when you are flying an approach with the engine making weird sounds lot's of things star flying though you head besides flying the plane.  It was a conscious effort to fly the plane and try not to think about the engine coming completely apart because you don't really know what is happening up there.

[carusoam]

Nice detective work, Bartman!

Best regards,

-a-

[mike_elliott]

38 minutes ago, bluehighwayflyer said:

I noticed that one of my intake tubes was loose during a routine hands on visual inspection during the course of an oil change earlier this year.  No engine monitor and no big deal.  

I had #2 come loose on my IO360 when I first purchased my F in cruise. At first, I noticed a vibration that got my attention. When I reduced the MP for decent, It really showed up as a horrible vibration. I thought the engine would shake off the mount, since #2 was still running at full MP and the rest reduced.

the intake runners are always checked at each oil change now..

[Bob_Belville]

Lynn tells me that 95% of the plane owners whose planes he maintains could not take off the cowl. or begin to diagnose a smell, noise, gauge reading etc. the subject came up when a long time owner of several planes was waiting to get a mechanic to pull the transponder out of the tray so that he could ship it off. I restrained myself until he was gone, it was not my place to tell the guy it was a one minute job. I better add that it was not a matter of the shop going to make an easy .5 hours, I suspect Lynn did not charge him and he would have gladly loaned him an allen wrench and coached him if the owner had asked. 

[1964-M20E]

I like to bring a solution to the mechanic when needed not a problem.

This is what is wrong.  This is what we need to do to fix it.  I already have the part and the cowling is already off.

 

 

 

 

[N201MKTurbo]

I once had an intake tube come completely off the cylinder. The engine continued to run well. I noticed it because the mixture knob was in an unusual position to get the mixture correct.

The cylinder can suck air in from an open port just as well as through the intake tube. The difference is that the air isn't going through the servo so the airflow isn't sensed by the servo. It also allows the other cylinders to suck some of its air through the open tube instead of the servo further reducing the airflow through the servo. So the mixture setting had to be a lot richer to get the proper fuel flow for the reduced airflow.

[RobertGary1]

Have you thought about uploading your EDM data here? I've done that in the past and its been helpful.

 

-Robert

[RobertGary1]

2 hours ago, 1964-M20E said:

I like to bring a solution to the mechanic when needed not a problem.

This is what is wrong.  This is what we need to do to fix it.  I already have the part and the cowling is already off.

Then just fix it and ask him to review your work.

-Robert

[Marauder]

3 hours ago, Bob_Belville said:

Lynn tells me that 95% of the plane owners whose planes he maintains could not take off the cowl. or begin to diagnose a smell, noise, gauge reading etc. the subject came up when a long time owner of several planes was waiting to get a mechanic to pull the transponder out of the tray so that he could ship it off. I restrained myself until he was gone, it was not my place to tell the guy it was a one minute job. I better add that it was not a matter of the shop going to make an easy .5 hours, I suspect Lynn did not charge him and he would have gladly loaned him an allen wrench and coached him if the owner had asked. 

What’s a wrench? 

I know a number of owners who are basically helpless when it comes to doing even the slightest bit of work on their plane. I think of this in terms of the zombie apocalypse — they will be the first eaten. For the first 7 years of ownership I did owner assisted annuals. It really helped me to understand the systems and to know when to ask for help.

 

[Hank]

3 hours ago, Marauder said:

For the first 7 years of ownership I did owner assisted annuals. It really helped me to understand the systems and to know when to ask for help.

What happened??? My 12th owner-assisted annual is just a few short months away.

Guess I'm just lucky that wrenches still fit my hand, although with my Mooney, there is much more screwdriver work . . . .

[RobertGary1]

20 hours ago, Hank said:

What happened??? My 12th owner-assisted annual is just a few short months away.

Guess I'm just lucky that wrenches still fit my hand, although with my Mooney, there is much more screwdriver work . . . .

I'm at almost 20. Initially I was going to various Mooney Service Centers but I found items missed that frightened me (cotter pin left off main gear, missing nut after replacing the aileron bellcrank, etc, etc).

 

-Robert

Edited September 27, 2017 by RobertGary1

[Guitarmaster]

What happened??? My 12th owner-assisted annual is just a few short months away.
Guess I'm just lucky that wrenches still fit my hand, although with my Mooney, there is much more screwdriver work . . . .

Especially on the belly! Uggg.

Sent from my XT1585 using Tapatalk

[Bartman]

Delayed longer than expected, but back in the air today.  I'm back to where I was before with #2 peaking first, and GAMI spread of 0.1 and purrs like a kitten.

[carusoam]

Nice Pirep, Bartman. And, nice Gami spread too.

Best regards,

-a-

[Bob_Belville]

14 hours ago, Bartman said:

Delayed longer than expected, but back in the air today.  I'm back to where I was before with #2 peaking first, and GAMI spread of 0.1 and purrs like a kitten.

Ditto, coming home from Summit Wednesday

Peak order: 2-1-4-3

FF 0.1 GPH

But I wonder about whether it is as good as the summary suggests - 2 and 1 peaked 40 seconds before 4 and 3. In the interval indicated FF continued to decrease but went back up to the value that 2/1 peaked at. (I continued to pull the mixture slowly using the vernier until the EDM indicated richest cyl had peaked.

Thoughts? (I'll ask Savvy to look at it - Paul @kortopates will probably reply.)

[kortopates]

1 hour ago, Bob_Belville said:

Ditto, coming home from Summit Wednesday

Peak order: 2-1-4-3

FF 0.1 GPH

But I wonder about whether it is as good as the summary suggests - 2 and 1 peaked 40 seconds before 4 and 3. In the interval indicated FF continued to decrease but went back up to the value that 2/1 peaked at. (I continued to pull the mixture slowly using the vernier until the EDM indicated richest cyl had peaked.

Thoughts? (I'll ask Savvy to look at it - Paul @kortopates will probably reply.)

This is what I measured

Time: 01:01:18-01:01:53

EGT2 peaked at 9.2

EGT1 peaked at 9.1

EGT3 peaked at 9.1

EGT4 peaked at 9.1

GAMI spread is 0.1

 

Although fairly quickly done, FF was monotonically decreasing as they were peaking and MAP and RPM were constant. So nicely done. But would really want to see an average of a few sweeps to ensure consistency. But it looks like good data too me!

[carusoam]

Leaning to define where peak is requires going s.l.o.w.l.y.....

But leaning slowly from full rich, you might miss your first waypoint, or top of descent, or other important things...

1) it helps to have a vernier mixture knob...

2) it helps to know the FF in the neighborhood where peak will occur.  

3) Lean roughly, using FF to get into the neighborhood.

4) Then use the vernier to sneak up on the peak.

5) Essentially, The heat capacity and thermal momentum can be a bit noisy and hide or delay what the instrument is seeing and displaying.

6) It helps to have quick responding EGT sensors, compared to the older last forever style..

7) if you lean too quickly and zip past peak... turn the mixture knob a couple of turns back to the right, then restart the LF... easy peasy.

8) The peak EGT is pretty static while the OAT and altitude are maintained.  

9) you should be able to reproduce the numbers going forward and backward if needed.

10) note the FF at the first and last to peak.  This is the Gami spread...

11) It is possible to have .1 Gami spreads.  They are really nice when going Deep LOP and shutting down....

PP thoughts on Gami spread. Not a CFI or engine guru...

Best regards,

-a-

[Bob_Belville]

1 hour ago, kortopates said:

This is what I measured

Time: 01:01:18-01:01:53

EGT2 peaked at 9.2

EGT1 peaked at 9.1

EGT3 peaked at 9.1

EGT4 peaked at 9.1

GAMI spread is 0.1

 

Although fairly quickly done, FF was monotonically decreasing as they were peaking and MAP and RPM were constant. So nicely done. But would really want to see an average of a few sweeps to ensure consistency. But it looks like good data too me!

Thanks Paul,

What I'm seeing on the EzTrends report is that

EGT2 peaks at 53:04 @ 9.2; EGT1                  53:05 @ 9.1; EGT4                  53:45 @ 9.3; EGT3                  53:46 @ 9.1

Between 53:05 and 53:45 the indicated FF dips as low as 8.1 but goes back up to 9.4. 

Your analytic software doesn't show that?  CSV attached.

Flt255_LF.csv

[Bob_Belville]

1 hour ago, Bob_Belville said:

Thanks Paul,

What I'm seeing on the EzTrends report is that

EGT2 peaks at 53:04 @ 9.2; EGT1                  53:05 @ 9.1; EGT4                  53:45 @ 9.3; EGT3                  53:46 @ 9.1

Between 53:05 and 53:45 the indicated FF dips as low as 8.1 but goes back up to 9.4. 

Your analytic software doesn't show that?  CSV attached.

Flt255_LF.csv

Paul @kortopates, I see what happened. All four EGTs peaked very close together. I continued to lean beyond peak to 50 LOP and then, while watching the inverted graphs, I must have screwed the mixture in a little for a better power setting. EGT3&4 hit a slightly higher peak which the EZT  software noted. 

All good. Happy, happy, happy.

[kortopates]

On 10/7/2017 at 9:37 AM, Bob_Belville said:

Thanks Paul,

What I'm seeing on the EzTrends report is that

EGT2 peaks at 53:04 @ 9.2; EGT1                  53:05 @ 9.1; EGT4                  53:45 @ 9.3; EGT3                  53:46 @ 9.1

Between 53:05 and 53:45 the indicated FF dips as low as 8.1 but goes back up to 9.4. 

Your analytic software doesn't show that?  CSV attached.

Flt255_LF.csv

I had to download your CSV data file, add an elapsed time column as =B15-TIMEVALUE("14:51:30") in order to get us on the same time line and then I could see what I believe you are referring too.

Notice that on Savvy's elapsed time line, my Gami spread data was between 1:01:24 to 1:01:53. The 1:01:53 elapsed time corresponds to to 15:53:23. 

After 1:01:53 window of the gami spread, indeed the FF does go back up to 9.4 for a few seconds, the last data point its at 9.4 is 1:02:14 elapsed or 1:53:44 actual time, the next 2 following seconds and data point is where Eztrends reported 3 & 4 peaking (again). But this is really invalid to go by that because. As you said, the leaning past peak the first time was done earlier as reflected by the gami spread reported above ending at 1:01:53  elapsed (or 15:53:23 actual). But only since the monitor is in Lean Find mode it continues to see it come back to peak in reverse with FF being enriched for a second peak. But if I simply expand the gami spread measuring window to include both peaks  it will report the same way EZTrends did (incorrectly).

Probably not saying anything differently than your last post but I was pretty confused till I dug into the details to resolve the time line differences and take a closer look.

I think a graphic does a much better job of illustrating it.

Edited October 8, 2017 by kortopates

[gsxrpilot]

I'm paying for the Savvy Analysis as well. How can I determine GAMI spread from the Savvy graph? Or should I just request analysis?