What does an intake leak look like in a turbo?

[Ragsf15e]

I have a funny #6.  On the ground (leaned out), EGT and CHT are lower than the others and it will actually stumble and 6 goes cold at 1000 rpm leaned out.  Mag check looks fine.  Climb looks normal.  Runs fine, however, I noticed in LOP cruise lower egt and higher cht than the others (and I think from the past).  I’m pulling engine data today.

What am I looking for in the engine data?  How would I flight test it?

I’m also pulling the top cowl to look around.  Is there anything/anywhere specific to look for at each junction?

Thanks!

[exM20K]

Pressurize the intake with the push side of a *clean* shop vac and hit everything with soapy water.

I've had leaks in:

• the pressure line to the MAP sender
• spark plug pressurization O-rings
• over-enthusiastic tightening of hose clamps on intake tubes
• the MAG pressurization line

Engine anomalies for the spark plug pressurization were like yours.

Engine data for the Mag line  showed unstable MAP (feedback loop w/ controller)

Engine data for MAP line showed lapsing MAP with altitude.

-dan

[Rick Junkin]

With an induction leak on a turbo, the leaking cylinder will run richer than the other cylinders in cruise at altitude. You identified  lower EGT and higher CHT running LOP, which I’d correlate with #6 possibly running ROP, potentially due to an intake leak.
EDIT: What you’re seeing on the ground at 1000RPM also correlates with a #6 induction leak, where #6 would now be running leaner than the the other cylinders.

A GAMI sweep could show you what’s happening, but there is a comparative check you can do specifically driven by setting two discrete manifold pressures and comparing the EGT changes across the cylinders. They should all be about the same. The complete details for performing this check are on the Savvy site.

ANOTHER EDIT: I couldn’t find the check on the Savvy site, so here’s what I use.

As for looking at general engine data and trying to identify it, that’s more difficult without comparing a recent flight to an historical flight before you noticed a change. It can be done but you have to look for very minute EGT deviations in the data when moving from one power setting to another.

You can also check for intake leaks on the ground with a spray bottle of soapy water and a buddy to move the prop for you.

Edited October 13, 2025 by Rick Junkin
Added details

[Fly Boomer]

1 hour ago, Rick Junkin said:

I couldn’t find the check on the Savvy site, so here’s what I use.

What ap are you using for that?

[Rick Junkin]

3 minutes ago, Fly Boomer said:

What ap are you using for that?

The Foreflight checklist function. 

[Ragsf15e]

On 10/13/2025 at 11:59 AM, Rick Junkin said:

The Foreflight checklist function. 

Rick,

I went out today and did the induction leak check and then the normal Savvy test profile including sweeps and mag check.  Here's a like to the flight if you want to have a look.

https://apps.savvyaviation.com/flights/shared/flight/10135421/f4cb8108-85d3-4a47-adf0-32b33235bc85

It still seems to me that #6 EGT /CHT is reacting different than the others, but its smooth and hard to say for sure.

Here's where each thing happened in the flight:

[Rick Junkin]

@Ragsf15e You'll need to share the link from the Savvy page, not the copied link address you have in your browser. You'll find it on the right side of the Savvy page when you have the flight data displayed. The link will look like this https://apps.savvyaviation.com/flights/shared/flight/8944398/75270480-f077-4e40-9c9d-5b70f51d9a31

[Ragsf15e]

22 minutes ago, Rick Junkin said:

@Ragsf15e You'll need to share the link from the Savvy page, not the copied link address you have in your browser. You'll find it on the right side of the Savvy page when you have the flight data displayed. The link will look like this https://apps.savvyaviation.com/flights/shared/flight/8944398/75270480-f077-4e40-9c9d-5b70f51d9a31

Sorry, try this…

https://apps.savvyaviation.com/flights/shared/flight/10135421/f4cb8108-85d3-4a47-adf0-32b33235bc85

[Rick Junkin]

3 minutes ago, Ragsf15e said:

Sorry, try this…

https://apps.savvyaviation.com/flights/shared/flight/10135421/f4cb8108-85d3-4a47-adf0-32b33235bc85

Perfect, I'll take a look and get back to you in a bit. Hopefully other folks will be looking as well 

[Ragsf15e]

31 minutes ago, Rick Junkin said:

Perfect, I'll take a look and get back to you in a bit. Hopefully other folks will be looking as well 

Yes, I also submitted it to savvy, so maybe they’ll see something.

[Rick Junkin]

15 hours ago, Ragsf15e said:

Rick,

I went out today and did the induction leak check and then the normal Savvy test profile including sweeps and mag check.  Here's a like to the flight if you want to have a look.

https://apps.savvyaviation.com/flights/10135421

It still seems to me that #6 EGT /CHT is reacting different than the others, but its smooth and hard to say for sure.

Here's where each thing happened in the flight:

Ok, looking at the data here https://apps.savvyaviation.com/flights/shared/flight/10135421/f4cb8108-85d3-4a47-adf0-32b33235bc85

Caveat emptor - I'm not a mechanic, so this analysis is based on my own self-education and limited experience assessing engine data. You will definitely want to run anything I come up with by an expert for validation. That's what I do with my analysis of my own data.

Bottom line up front: What I see in the data shows issues with the ignition system and indications of an intake leak on the even side of your engine, most likely at the #6 intake port. EDIT: However, all of these things can affect each other. So it's often best to make one change, reassess performance, and then proceed to the next change if things haven't resolved. The easiest check is the soapy water check for an intake leak, so I'd start there.

Here are my observations.

1. Induction check - The even cylinder EGTs dropped less than the odd cylinders, with #6 dropping the least. The even side drops were 160/160/135 for #2/#4/#6, and the odd side were 190/210/190 for #1/#3/#5. Less of a drop indicates a leaner mixture which means more air, hence an intake leak on on the even side. A single leak on one cylinder could be bad enough to affect the whole bank. From the data #6 looks to be the worst, so that's where I'd start with a physical inspection using soapy water and intake pressurization. But I'd look at the whole even side. If you look at the tail end of the data trace for #6 you'll notice a "bounce" in the EGT that isn't present on the other cylinders, further nominating #6 as the source of the problem.

2. GAMI sweeps - These indicate your cylinders are not well balanced for LOP ops. There are 3 available data sets here. The first, moving from rich to lean, yields a spread of 0.8gph; the second, moving from lean to rich, is 1.1gph; and the third, moving from rich to lean, is 1.2gph. Here's the sampling of the best case, but you can see the other two sets of peaks as well.

There's some work to be done here, but not before you take a look at your ignition. Which leads us to...

3. LOP Mag check - The first mag you checked looks to be a little weak, especially on the even side of the engine. #4 and #6 in particular. And then #3 on the second mag is a bit erratic, which may be a weak plug or wire, and #4 & #6 are again weaker than #2. You'll want to get this figured out first and then look at your GAMI spread again.

EDIT: Disregard the comparison of #4 & #6 to #2. Minor differences between EGTs are expected and dependent more on probe placement and other flow factors that vary between cylinders. Comparing EGT behavior across multiple cylinders at different conditions is valid. Comparing absolute EGT values in most cases is not. My bad.

Once again, I'm not a mechanic and this is an analysis of your data based on my own learning and limited experience. Get an expert's assessment before spending any money.

[Ragsf15e]

13 minutes ago, Rick Junkin said:

Ok, looking at the data here https://apps.savvyaviation.com/flights/shared/flight/10135421/f4cb8108-85d3-4a47-adf0-32b33235bc85

Caveat emptor - I'm not a mechanic, so this analysis is based on my own self-education and limited experience assessing engine data. You will definitely want to run anything I come up with by an expert for validation. That's what I do with my analysis of my own data.

Bottom line up front: What I see in the data shows issues with the ignition system and indications of an intake leak on the even side of your engine, most likely at the #6 intake port.

Here are my observations.

1. Induction check - The even cylinder EGTs dropped less than the odd cylinders, with #6 dropping the least. The even side drops were 155/160/140 for #2/#4/#6, and the odd side were 180/200/180 for #1/#3/#5. Less of a drop indicates a leaner mixture which means more air, hence an intake leak on on the even side. A single leak on one cylinder could be bad enough to affect the whole bank. From the data #6 looks to be the worst, so that's where I'd start with a physical inspection using soapy water and intake pressurization. But I'd look at the whole even side. If you look at the tail end of the data trace for #6 you'll notice a "bounce" in the EGT that isn't present on the other cylinders, further nominating #6 as the source of the problem.

2. GAMI sweeps - These indicate your cylinders are not well balanced for LOP ops. There are 3 available data sets here. The first, moving from rich to lean, yields a spread of 0.8gph; the second, moving from lean to rich, is 1.1gph; and the third, moving from rich to lean, is 1.2gph. Here's the sampling of the best case, but you can see the other two sets of peaks as well.

There's some work to be done here, but not before you take a look at your ignition. Which leads us to...

3. LOP Mag check - The first mag you checked looks to be a little weak, especially on the even side of the engine. #4 and #6 in particular. And then #3 on the second mag is a bit erratic, which may be a weak plug or wire, and #4 & #6 are again weaker than #2. You'll want to get this figured out first and then look at your GAMI spread again.

Once again, I'm not a mechanic and this is an analysis of your data based on my own learning and limited experience. Get an expert's assessment before spending any money.

Excellent, thanks!  When savvy gets back to me ill let you know what they said as well.

I hadn’t realized the whole even side egt dropped differently, so I’ll check that out.  I did realize the roughness during the mag check but it was really LOP, maybe 75 degrees or so, so I think that’s just as stressed as you can make the ignition.  That being said, I did notice the roughness on the right side mag.

Finally, I agree about the gami spread numbers you saw but that’s weird.  It has gami injectors and was previously around 0.5gph spread.  It runs great lop.

[Rick Junkin]

2 minutes ago, Ragsf15e said:

Finally, I agree about the gami spread numbers you saw but that’s weird.  It has gami injectors and was previously around 0.5gph spread.  It runs great lop.

I think there is a good chance you'll see the spread narrow back to 0.5gph once you get the other issues sorted. Good luck!

And yes, please do share the feedback you get from Savvy. Another opportunity for me to learn something.

[Ragsf15e]

On 10/20/2025 at 5:00 PM, Rick Junkin said:

I think there is a good chance you'll see the spread narrow back to 0.5gph once you get the other issues sorted. Good luck!

And yes, please do share the feedback you get from Savvy. Another opportunity for me to learn something.

Savvy got back to me. Basically they said there could be a slight induction leak near #6, but probably not too big.  They did show that #3 is hitting peak much before the other cylinders and recommend cleaning that injector.  This is likely the cause of the larger gami spread.

[Rick Junkin]

Excellent. I'm looking forward to hearing if this resolves your issues.

[Will.iam]

On 10/21/2025 at 11:28 PM, Ragsf15e said:

Savvy got back to me. Basically they said there could be a slight induction leak near #6, but probably not too big.  They did show that #3 is hitting peak much before the other cylinders and recommend cleaning that injector.  This is likely the cause of the larger gami spread.

Interesting my #3 cyl is also the richest of the pack. I have a smaller gami injector in that cyl but once i was at .2 spread gami would not give me a smaller injector stating the next size smaller would put #3 more than .2 to lean on the other side of the pack.