Engine rough, high EGT on take off

[Jbarab]

Hello all. This is my first post.

Last summer, I bought my Bravo (1996, 1600 hours on engine, 3,700 TTAF) and love it. This is the first Mooney I have owned. It is fast and was so reliable. Last month I flew from NY to Miami and back, everything working flawlessly. But now I have a problem and hope the community can steer me in the right direction.

Twice recently I took off just 50 pounds under gross weight. Both times, the air temperature was cool, run-up was normal, the mixture was full rich, the ground roll seemed slow which I attributed to weight. Both times, when I rotated, I experienced anemic climb, engine roughness, shaking, EGT spikes (various cylinders but I can't say which) and, the second time, TIT climbed to 1680. Both times, I lowered the nose to improve airspeed. In a few seconds, everything returned to normal: normal engine sound, EGTs all even (and low because mixture full rich), no more shaking, no roughness, normal power.

During both take offs the fuel flow meter showed 29.9 gph. When the EGTs and TIT spiked the fuel flow was showing a constant flow of 29.9. I'm sure there was no water contamination in the fuel and as far as I can see there wasn't other contamination such as sealant, although the last time I took off I was headed for my appointment at Wet Wingologists in Ft. Lauderdale for a tank reseal meaning that the sealant is deteriorated. But I have never seen particles in the fuel in the tester.

Shortly prior to these flights, I had the injectors and plugs cleaned, engine fuel servo screen cleaned, mixture control checked.

Unless it is pure coincidence, it seems that nose up pitch triggers the problem and level attitude resolves it. I consulted four mechanics and none has an answer that explains these symptoms, that is, apparent severe leaning of fuel to the cylinders despite the fuel flow meter showing normal fuel flow with problem occurring only at take off and resolving with level attitude.

Has anyone had this problem? Any ideas? 

 

[LANCECASPER]

1 hour ago, Jbarab said:

Hello all. This is my first post.

Last summer, I bought my Bravo (1996, 1600 hours on engine, 3,700 TTAF) and love it. This is the first Mooney I have owned. It is fast and was so reliable. Last month I flew from NY to Miami and back, everything working flawlessly. But now I have a problem and hope the community can steer me in the right direction.

Twice recently I took off just 50 pounds under gross weight. Both times, the air temperature was cool, run-up was normal, the mixture was full rich, the ground roll seemed slow which I attributed to weight. Both times, when I rotated, I experienced anemic climb, engine roughness, shaking, EGT spikes (various cylinders but I can't say which) and, the second time, TIT climbed to 1680. Both times, I lowered the nose to improve airspeed. In a few seconds, everything returned to normal: normal engine sound, EGTs all even (and low because mixture full rich), no more shaking, no roughness, normal power.

During both take offs the fuel flow meter showed 29.9 gph. When the EGTs and TIT spiked the fuel flow was showing a constant flow of 29.9. I'm sure there was no water contamination in the fuel and as far as I can see there wasn't other contamination such as sealant, although the last time I took off I was headed for my appointment at Wet Wingologists in Ft. Lauderdale for a tank reseal meaning that the sealant is deteriorated. But I have never seen particles in the fuel in the tester.

Shortly prior to these flights, I had the injectors and plugs cleaned, engine fuel servo screen cleaned, mixture control checked.

Unless it is pure coincidence, it seems that nose up pitch triggers the problem and level attitude resolves it. I consulted four mechanics and none has an answer that explains these symptoms, that is, apparent severe leaning of fuel to the cylinders despite the fuel flow meter showing normal fuel flow with problem occurring only at take off and resolving with level attitude.

Has anyone had this problem? Any ideas? 

 

Still sounds like clogged injector(s), or maybe your fuel system needs to be rebuilt. I used to own a ‘96 M20M (N9153Z).

[carusoam]

Welcome aboard Jb!

1) Long T/O

2) shaking

3) EGT spikes

4) Slow climb

5) Engine monitor

 

First thing we do… share the data. 

6) Download the data from the monitor… upload it to Savvy… click the share button… copy link here….  We can all see what is going on this way…

7) High EGTs indicate fuel burning in the exhaust… where you want fuel to be burning in your cylinders….

8) Often, valves not behaving properly… allow for spiky EGTs and lack of power…

9) EGT challenges will be clear in your JPI graphs when you share them…

10) If the data shows to check the valves… the dental camera is the next step…

11) pics of nice valves… look like pizzas…

12) If you are not sure if the T/O distance is really longer… that can be accurately measured as well… a WAAS source and CloudAhoy works really well…

13) you didn’t mention what the CHTs were doing… they are often the corroborating helpful factor…

14) +1 for fuel flow issues… blocked fuel injectors can be a common easy to fix challenge…. Get the data going!

15) If there is something stuck in a fuel injector… you want to catch it, to find out where it came from…

16) Was that one EGT or six? Downloading the data will point directly at a single cylinder challenge…

17) Ignition challenges, as pointed out by Ross, below… A nice really elaborated run up, allowing the EGTs to rise and fall completely… makes nice graphs for problem solving too… if the peaks are different, a mag timing challenge may be occurring… a misbehaving plug may be obvious…

 

Let’s say…. This isn’t normal behavior for a Bravo… might be really easy to get fixed…

PP thoughts only, not a mechanic…

Best regards,

-a-

[Shadrach]

Hard to say without seeing data. But my initial take is that the ignition system is tired. EGT spikes are typically related to a plug or mag dropping out. Engine will run rougher because the combustion event in the affected cylinder[s] is propagating slower due to the single point of ignition. This creates an imbalance of power pulses from cylinder to cylinder as well as decreased performance.
 

I would do a high power inflight mag check with the engine leaned as far as will allow smooth operation. That should provide a clear picture as to the condition of your ignition system.

[Jbarab]

Thank you all so much for your responses and for your warm welcome.

I will follow your advice and will start by extracting the JPI data, sending it to Savvy and sharing it here, after I learn how to do so. 

I will also send out the Slick mags for overhaul. They are well overdue. And I will have the fuel injectors examined and cleaned (again). If the tank sealant is breaking down the bits must be going somewhere. The logs do not show a reseal in the plane's 26 years.

By the way, Lancecasper, my M20M is N755TT. 

I really appreciate all your help. Many thanks. 

Regards,

Jesse

 

[LANCECASPER]

6 minutes ago, Jbarab said:

Thank you all so much for your responses and for your warm welcome.

I will follow your advice and will start by extracting the JPI data, sending it to Savvy and sharing it here, after I learn how to do so. 

I will also send out the Slick mags for overhaul. They are well overdue. And I will have the fuel injectors examined and cleaned (again). If the tank sealant is breaking down the bits must be going somewhere. The logs do not show a reseal in the plane's 26 years.

By the way, Lancecasper, my M20M is N755TT. 

I really appreciate all your help. Many thanks. 

Regards,

Jesse

 

Ok, yours is serial number 215, my '96 was 209.

Aero Accessories in Van Nuys did a great job on overhauling my mags. Quick turn around and excellent work at a fair price.

[201Steve]

Go to savvy website and download the instructions for lean of peak in flight mag check if you intend on analyzing the data and you still feel comfortable flying it. 

[Shadrach]

17 hours ago, Jbarab said:

Thank you all so much for your responses and for your warm welcome.

I will follow your advice and will start by extracting the JPI data, sending it to Savvy and sharing it here, after I learn how to do so. 

I will also send out the Slick mags for overhaul. They are well overdue. And I will have the fuel injectors examined and cleaned (again). If the tank sealant is breaking down the bits must be going somewhere. The logs do not show a reseal in the plane's 26 years.

By the way, Lancecasper, my M20M is N755TT. 

I really appreciate all your help. Many thanks. 

Regards,

Jesse

 

I wouldn’t shotgun this. Tackle one system at a time. If you have slick mags that are way past TBO, it’s entirely possible that the problem is there. No reason to dig into the fuel system until you’ve ruled out the ignition. Opening it up it’s just another opportunity to introduce a problem.

 

it’s not entirely unusual to have an ignition problem that doesn’t show up during run up. If you fly long enough you will encounter an ignition problem that only manifests under the most demanding conditions. A 1700 RPM run up is not very demanding on the ignition.

Edited April 17, 2022 by Shadrach

[Jbarab]

Okay. I will start with the mags.

Meanwhile, I'm learning how to download and send the JPI data. First thing, I have to buy a JPI USB download box.

Thanks.

[triple8s]

Two symptoms makes me lean towards a fuel issue, lower the nose and conditions improve, the higher the nose the more is required to pump the fuel to the engine. I know this from experience.  The other thing is the fuel system was touched recently (worked on). When things are working and you disturb them sometimes they cause other issues. The airlines have a thing called “maintenance induced failure” which addresses this phenomenon.  
 Now that I think about it those symptoms remind me of an unpleasantly exciting flight in a Bravo and it was a fuel issue and after maintenance as well. As I recall it was pumping plenty of fuel it just wasn’t all making it to the engine.

[MDMooney]

Were you ever able to get your issue resolved/ what did it end up being? Trying to help a friend with a similar issue.

Edited March 19, 2023 by MDMooney

[LANCECASPER]

22 hours ago, MDMooney said:

Were you ever able to get your issue resolved/ what did it end up being? Trying to help a friend with a similar issue.

It's good to quote the post or ping the person  @Jbarab

[Jbarab]

The issue stopped.

I think it was a clogged injector but I'll never know.

After a couple more of the events I described, my mechanic found a clogged injector. But the injectors had been inspected and cleaned twice before in the less than one year I had owned the plane. So I asked him to send out the fuel servo and spider for overhaul. The engine ran smoother with the overhauled parts and I haven't had the problem since.

I keep expecting the problem to recur. I can't imagine where the material came from that got into the injector. If it passed through the various filters to get there, why won't that continue to happen?

By the way, Carusoam suggested  that I send the engine monitor data for analysis. After buying a cable and USB box from JPI it turned out that my monitor has no memory capability. 

 

 

 

 

 

[Fly Boomer]

3 hours ago, Jbarab said:

By the way, Carusoam suggested  that I send the engine monitor data for analysis. After buying a cable and USB box from JPI it turned out that my monitor has no memory capability. 

Is your monitor an EDM-700?  I haven't verified this yet, but I learned that it is a possibility (no memory) by talking to JPI.

[Jbarab]

Yes, it is am EDM- 700.

You look through the menu on the unit in your plane to find out whether or not memory was installed.

JPI told me memory can be added but that requires removing, sending, reinstalling. I haven't done it yet. 

[Fly Boomer]

11 minutes ago, Jbarab said:

Yes, it is am EDM- 700.

You look through the menu on the unit in your plane to find out whether or not memory was installed.

JPI told me memory can be added but that requires removing, sending, reinstalling. I haven't done it yet. 

I'll check out the documentation, but is the menu that contains that info accessed by holding both buttons simultaneously?  Do you know what to expect in the programming menu if there is no memory?  The documentation, as I recall, just gives the option to turn recording on or off.

They told me the same regarding adding memory. 

[LANCECASPER]

14 hours ago, Jbarab said:

The issue stopped.

I think it was a clogged injector but I'll never know.

After a couple more of the events I described, my mechanic found a clogged injector. But the injectors had been inspected and cleaned twice before in the less than one year I had owned the plane. So I asked him to send out the fuel servo and spider for overhaul. The engine ran smoother with the overhauled parts and I haven't had the problem since.

I keep expecting the problem to recur. I can't imagine where the material came from that got into the injector. If it passed through the various filters to get there, why won't that continue to happen?

By the way, Carusoam suggested  that I send the engine monitor data for analysis. After buying a cable and USB box from JPI it turned out that my monitor has no memory capability. 

After doing this many times on Bravos I've owned I'm suspicious that taking them apart and inspecting and cleaning them as often as is called for is what introduces clogs in some cases. 

[Pinecone]

Mike Busch and George Braly agree.

[Jbarab]

To respond to Fly Boomer's question, I don't remember well but I think when I scrolled, holding however many buttons down,  the option to turn memory on and off did not exist and that was how one knows that there is no memory function installed.

I have minimal confidence in this response. It was a year ago.

[Fly Boomer]

14 hours ago, LANCECASPER said:

After doing this many times on Bravos I've owned I'm suspicious that taking them apart and inspecting and cleaning them as often as is called for is what introduces clogs in some cases. 

According to one of the GAMI/APS guys, the most common debris they find is microscopic red strands from shop rags.

[LANCECASPER]

1 hour ago, Fly Boomer said:

According to one of the GAMI/APS guys, the most common debris they find is microscopic red strands from shop rags.

Plus they keep re-using the Hoppes #9 fluid and the possibility exists of very small particles ending up in the injector

After a clog happened once in my Bravo I now insist that we use my new Hoppes #9

[carusoam]

The scary part of repeated fuel injector clogs….

There can be an upstream rubber lined fuel hose disintegrating…. Sending small black pieces of rubber towards the injectors…

Try to catch what comes out of the fuel injector for identification purposes…. 

PP memories only, not a mechanic…

Best regards,

-a-