Clogged injector?

[Godfather]

Trying to diagnose a high egt value I noticed in a run up today. One cylinder #5 is reading much higher and does not look like a mag or spark plug problem. The first peak is full rich. The second peak where the orange (#5) dives is where I was leaning it out. 

I had my mechanic pull the injector but and check for blockage but nothing was noted. Could the obstruction be upstream in the fuel distribution spider?

Thanks

[carusoam]

Looks like a classic dirty, slow flowing FI...

Is this JPI graph the before or after cleaning?

Might want to invite Paul @kortopates for his input...  Paul has the expertise on getting the most out of engine monitors...

Best regards,

-a-

 

[Shadrach]

Why do you think it’s a mixture problem and not ignition related?

[carusoam]

Ross,

Only because, the GF would have mentioned a problem during the run-up if a plug has gone cold...

 

Note to the GF...  got a full flight of data you can share?  Including start and the run up could be helpful... having the full CHT data to go with that is corroborating evidence...

Any knowledge of the spark plugs you have in the engine?

What is the time frame of this graph?

 

Going on my first guess probably won't be very helpful...  

 

The Elevated EGT in the first part of the graph turns into a cold EGT in the second part of the graph.

Is there a Leaning event that causes that flame to get extinguished?

 

I think I have two ideas that point to a fuel blockage... higher EGT during leaning, lower EGT when leaned too far...

one idea that points to a plug not working... higher EGT caused by a single plug failure.  But can't explain the second drop in EGT.... unless the second plug decided to quit... (parts bouncing around inside the cylinder?)

 

Ross, what are your thoughts?

 

PP thoughts only, not a mechanic...

Best regards,

-a-

 

[Godfather]

16 minutes ago, Shadrach said:

Why do you think it’s a mixture problem and not ignition related?

It very well could be but during the mag test it behaved normally and when I leaned the engine that cylinder appeared to go excessively lean?

 

25 minutes ago, carusoam said:

Looks like a classic dirty, slow flowing FI...

Is this JPI graph the before or after cleaning?

Might want to invite Paul @kortopates for his input...  Paul has the expertise on getting the most out of engine monitors...

Best regards,

-a-

 

This was after the mechanic checked it. He might have used compressed air but he was on his way home from work and will not have time to work on it until the weekend. 

[Jim F]

It could be upstream but not likely. To be clear you checked both mags?

its a little work but you could swap #5 and #3 injectors and see if the problem moves. That is what I would do if I was away from home. Also verify you don’t have a big intake leak #5

jim

[carusoam]

Nice point, Jim.

There are a couple of rubber hose connectors on the R's intake runners... that would be worth looking at to find if something may be coming loose allowing extra air into that cylinder...

A leak should be more noticeable during high vacuum/low MP operations....

PP only, not nearly as skilled as these other gentlemen...

Best regards,

-a-

[Shadrach]

22 hours ago, carusoam said:

Ross, what are your thoughts?

I’m still forming them. It’d be helpful to see things like RPM, FF, MP.

I always try to ruleout ignition issues first when trouble shooting a single cylinder issue because my anecdotal evidence suggests that that is the more common problem. 

If what I’m looking at is a constant RPM and manifold pressure setting with the mixture being leaned all the way to rough, then I agree with you that this is likely a air/fuel issue.  The second slight EGT rise before the precipitous drop also point to a lean condition. The flame front gets so slow (also happens with a bad mag or plug) that greater portion of the event Is occurring in the exhaust stroke and exhaust pipe which causes EGT to climb again just before the mixture becomes too lean to support combustion.

Edited January 20, 2018 by Shadrach

[kortopates]

Sorry, but insufficient data to tell if its ignition or mixture. EGTs need to be corroborated with CHT and FF. I don't see any of that, otherwise its too easy to draw the wrong conclusion.

Without the dialog, I can say that I was led to think the graph looks like a mag test isolating one mag at a time suggest a bad plug and thus my first impression was an ignition issue like Ross @Shadrach questioned.  But the dialog says that it wasn't that at all but leaning the engine from ROP to LOP,  but I can't tell if FF is shown. Without the FF I am left more confused to understand the 2 peaks.   

Anyway, in the interest of helping, we can usually separate mixture from ignition by looking at CHT. If they both move together then we can assume its mixture as Anthony @carusoam speculated. But clogged injector won't cause it to peak much higher than the others EGT wise  at the same time but it will peak much sooner time wise  than the others (on less fuel) and because of that will be much lower on the LOP side since its running more LOP. But judging by the other EGTs they look to be peaking pretty close to one another (but again changes in FF is are unknown so there is too much speculation). On the other hand, if EGT and CHT are moving opposite from one another that a sign of being ignition induced. There is nothing there to suspect or eliminate induction leaks at this point - at this stage we need to think of induction as merely a mixture anomaly - and we're not there yet with this little to go on. Hope that makes sense.  Personally, I would want to do more data analysis before turning any wrenches. Flying the Savvy Test profile would for example provide the diagnostic data to point in the right direction; if the plane isn't grounded at this point.

Another oddity that needs to be considered and understood is that we're seeing significant fluctuations in all EGTs, but I am assuming "significant" without knowing sampling rate and scale. If this was during an isolated mag (i.e. mag check) this would be likely ok or normal, but if its truly during just a leaning period then this is not right and should be resolved. It could simply be excessive background noise by improper installation of routing the EGT leads along ignition wires too. But too hard to say with only a snippet of data.

[carusoam]

Next steps for the GF...

Get familiar with flying the Savvy test profiles and collect a full set of data for analysis...

There is a lot that can be gained before any money needs to be spent...  Great for CBs...  and those who just aren't sure yet... 

Paul has a relationship with the Savvy company.  I am just a PP with a mission of knowing as much as I can about my plane...

https://savvyanalysis.com/home

 

 

[Godfather]

I apologize for letting this post go cold. Very busy over the last week with no time to look at the plane. 

Over the weekend my mechanic took out the fuel distribution spider and the injector and said everything was very clean. He put it back together and ran the engine on the ground reporting that everything was working normally. This engine is about 100 hrs SMOH and everything was reman’d to factory new specs. A few injectors have been sent back to gami to even the spread (including this #5 injector). 

The JPI sensors all read exactly the same with a cold engine.  

When I started the plane today it seemed a little rough but it has been ground run 4 times now and I’m not sure if the spark plugs are a little fouled. 

The #5 egt acted similar to previous run showing ~150 deg warmer until I leaned hard on the 1600-1700 runup which brought the others up to the same level. 

Attached is the takeoff that started my concern. I did not notice the higher egt during runup. On liftoff I noticed the egt was noticeably high. I continued to watch for a few seconds as the cht on that cylinder started to rise abnormally so I reduced power and landed. 

I need to reduce the sample rate to 1 seconds vs the 6 seconds it’s set on. I’d also like to do a proper lean test but I’m not sure it’s a good idea to take off with the data I’m looking at (I really have NO idea what I’m looking at). Probably need to join savvy to tap into the knowledge base but at this point I just want some opinions. 

 

I did move the slider from pic to pic to show the peak cht on #5. Note the first pic had #5 egt peak at 1560. 

[MB65E]

A Failed/failing Spark during a low power run up won't show up. But on take off you'll notice it. I'd go after the plugs on that cylinder.

Next,  if it gets better or there is a problem that you've found, inflight mag checks really show you if you have a good ignition system or not. 

-Matt

[carusoam]

It would make sense to share what you are seeing with the good people that balanced your fuel injectors... (gami)

Sounds like something could be amiss with that.

Is your mechanic familiar with the fuel injector numbers and what cylinder they belong in?  Looking for a possible mix-up...

 

as before...

If you have the full set of data showing EGTs and CHTs,  From run-up to landing...  that is more helpful than just the close up of the EGTs...

The one set of data is helpful, but a full graph is like a million sets of points.  Kind of like a picture.

Best regards,

-a-

 

[Shadrach]

Godfather,

Are you in the midst of a GAMI set up?  What was the approximate OAT at the time of the pictured EGT/CHTs occured?   I do not think this is a ignition issue given that both EGT and CHT are what I consider to be on the high side (at least for what I'm used to seeing).  A bad lead or plug would cause an increase in EGT due to  the slower combustion event but a decrease in CHT.  It appears that #5 is indeed a bit leaner than the rest.  The question is why.

Do all of the M20R drivers at this party see CHTs above 350° during the take off run? 

One other thing, before all of the usual squawking about raw EGT number meaning nothing.  They indeed do mean something.  They mean that the thermocouple giving the read out is either seeing that temp or it is malfunctioning.  So unless the cylinder in question  (#5) can be leaned to at least 1760°, this engine is likely running too lean on take off. 

I wish you had leaned for peak in the air. It would have been pretty telling if the #5 EGT peaked way before the others, it would confirm the cylinder's lean condition. 

Edited January 26, 2018 by Shadrach

[Godfather]

@Shadrach the OAT was probably in the 25-35 deg F. The last gami injector fine tuning was done a couple months ago.  I’m going to closely look at previous flights to get more of a baseline. 

[Shadrach]

23 minutes ago, Godfather said:

@Shadrach the OAT was probably in the 25-35 deg F. The last gami injector fine tuning was done a couple months ago.  I’m going to closely look at previous flights to get more of a baseline. 

If the numbers I am looking at are full rich,  I would say most if not all of your cylinders would benefit from a bit more fuel on take-off.  The good news is that your CHTs look relatively well balanced aside from #5 which is quite warm for a take off run in freezing temps.  If the OAT were in the mid 90s, I am sure it'd be north of 400°.   #2, 3, 5 and 6 would likely be on the warm side as well.

 

 

Edited January 26, 2018 by Shadrach

[Shadrach]

11 hours ago, Godfather said:

I did move the slider from pic to pic to show the peak cht on #5. Note the first pic had #5 egt peak at 1560. 

This is only telling if you slowly through the mixture range.  If 1560° is the true peak EGT for #5 and 1510° is full rich, I would perform only the shortest ground run tests.  Taking off with #5 running 50° ROP is really hard on the cylinder.

[Piloto]

A clogged injector will always peak first before the others. Try swapping the probe.

José

[Shiny moose]

First Check your number 5 plugs, Ohm check them, or if you don’t have a meter just swap Both #5 plugs to a different cylinder and see if the high EGT at TO power follows the plugs, if it does not follow the plugs, swap EGT probs(please label them) then look for a #5 intake leak, gaskets, rings, clamps rubber tubes(cont), cracks, I’m betting a failed plug

[Shadrach]

6 hours ago, Shiny moose said:

First Check your number 5 plugs, Ohm check them, or if you don’t have a meter just swap Both #5 plugs to a different cylinder and see if the high EGT at TO power follows the plugs, if it does not follow the plugs, swap EGT probs(please label them) then look for a #5 intake leak, gaskets, rings, clamps rubber tubes(cont), cracks, I’m betting a failed plug

I to initially thought it was likely an ignition problem. However there are now many pieces of evidence to contradict that theory. How would you explain that number five has the highest CHT (by a significant margin) of all cylinders? I’ve never seen a dead plug cause an elevated CHT, quite the opposite.  As to the possibility of an intake leak, that really wouldn’t create much in the way of symptoms at wide open throttle. I am dubious that it would provide enough additional air to lean the #5 EGT by 200°. 

Edited January 27, 2018 by Shadrach

[carusoam]

Adding to Ross' thoughts... and Some background ideas to keep in mind...

IO550 LBs have a high CHT on #5 where the cowling molds around the alternator(?) a small hole has been added on a few cowlings to help make a difference there.

You might See a 50°F High CHT without the pixie hole, a +25°F CHT with the pixie hole...  

FF of a 310hp IO550 is set to 27.2 gph by STC...  considered by some, not enough to keep CHTs low enough.  If able they may add a gallon or three to improve cooling...

what FF are you seeing at WOT on the ground? What altitude is your airport at?  does you cowling have a pixie hole in it?

Do you have a blue box for leaning your EGT, or a white box on your G1000?  How far below the blue box are you on departure?

PP things I have read around here.  Check with your mechanic for appropriateness for your plane....

Best regards,

-a-

[Shadrach]

4 hours ago, carusoam said:

Adding to Ross' thoughts... and Some background ideas to keep in mind...

IO550 LBs have a high CHT on #5 where the cowling molds around the alternator(?) a small hole has been added on a few cowlings to help make a difference there.

You might See a 50°F High CHT without the pixie hole, a +25°F CHT with the pixie hole...  

FF of a 310hp IO550 is set to 27.2 gph by STC...  considered by some, not enough to keep CHTs low enough.  If able they may add a gallon or three to improve cooling...

what FF are you seeing at WOT on the ground? What altitude is your airport at?  does you cowling have a pixie hole in it?

Do you have a blue box for leaning your EGT, or a white box on your G1000?  How far below the blue box are you on departure?

PP things I have read around here.  Check with your mechanic for appropriateness for your plane....

Best regards,

-a-

So the STC specifies exact full rich FF, not a minimum? 27.2gph max for a 310hp engine is absolutely sub-optimal at full power. If I had that upgrade, my hangar fairy would figure out a way to bump FF.  I’ve heard of the pixie hole and the tendency for #5 to run hot. However, the fact that it’s 380° on the take off run  with OAT of 25 - 35° Suggests this is a F/A issue, not a cooling issue.   It is likely magnified by the cold weather given that a 310hp engine on a standard day can make considerably more than 310hp on a 25° high-pressure day and limited to 27.2gph.    No wonder it looks lean across the board. Who owns the STC?  

So we have an engine set up on the lean side for a standard day, running in cold dense air, with a possible F/A issue on the one cylinder that is known to lack adequate cooling airflow?

Edited January 28, 2018 by Shadrach

[Godfather]

Thank you everyone for all the help so far.  To answer some background questions...

The engine does have the baffling mod done about 12 years ago per the specs from a Mooney employee at OSH. 

The fuel flow is just over 29 gph and has been keeping the cylinders cool on climb out. 

Using the JPI 900 which I find just ok and does not have a white box like the factory gauge. 

[Godfather]

Plugs were removed and ohms checked were in great condition but replaced with two new ones because I want to narrow down the problem areas. 

Egt probe swapped and the problem stays with the cylinder. Calling Paul at Gami on Monday for a new injector or two. I’m almost 100 percent sure this is a fuel related issue and that cylinder had a bravo injector vs a echo / foxtrot flow classification. 

Thanks again for the help and I’ll report back when my mechanic has time to work on it again. 

[Godfather]

23 minutes ago, Shadrach said:

So the STC specifies exact full rich FF, not a minimum? 27.2gph max for a 310hp engine is absolutely sub-optimal at full power. If I had that upgrade, my hangar fairy would figure out a way to bump FF.  

Who owns the STC?  

So we have an engine set up on the lean side for a standard day running in cold dense air with a possible F/A issue on the one cylinder that is known to lack adequate cooling airflow?

Mooney owns the STC now. My JPI flashes at me on every single takeoff. They are unwilling to bump the “unsafe” limit. 

Edited January 28, 2018 by Godfather