EGT Rising Fast on Two Cylinders

[AaronDC8402]

I just returned from a 450 nm round trip with a slight engine issue. After exiting some rough IMC, I noticed the cowl vibrating. The only other time I notice this is when over-leaning the engine just prior to putting a little richness back in. After noticing the cowl vibration, I put some fuel back in and the vibration went away. I pretty quickly noticed that cylinders 1 and 2 were running the typical ~1450 deg F EGT, but 3 and 4 were running much cooler EGT (as if they were running too rich). Cyl temps were also a little cool on 3 and 4, but all were within typical ranges.

My theory is that the rough IMC loosened some debris, and it's now clogging fuel injectors 1 and 2. Any other suggestions to consider?

 

 

[FoxMike]

You might look around for some induction leaks.

[carusoam]

Aaron,

It is really cool when MSers post a graph from there engine monitor...

Quick and accurate feed back is the norm.

We also have a member that reviews engine Ops for a living.  Paul is currently in China I think... But the internet works there too. Sort of... 

It is best to give as much detail as you can, like MP, rpm, FF, CHTs and EGTs...  These are the fingerprint of the challenge you might be seeing.

Best regards,

-a-

[AaronDC8402]

I'm honestly not sure how to get a graph out of the engine monitor. It's a EDM700 that I haven't put much effort into learning other than watching the EGT and Cyl temp bars for reference. The numeric display is not working correctly, so exact numbers aren't available. We're planning to upgrade the EDM at some point sort of soon.

By my memory (and a few cell phone pictures), cruising at 10,000 MSL, 20" MP, 2500 rpm, 12.5 gph, 

cyl 1: 1450 deg F EGT; 350 deg F cyl temp

cyl 2: 1450 deg F EGT; 300 deg F cyl temp

cyl 3: 1050 deg F EGT; 300 deg F cyl temp

cyl 4: 1100 deg F EGT; 350 deg F cyl temp

 

From this scenario, leaning further decreases cyl 1 and 2 EGTs (already LOP) and increases cyl 3 and 4 EGT's (still way ROP). Further leaning also results in engine roughness.

 

Edited August 31, 2016 by AaronDC8402

[AaronDC8402]

Update:

Found debris in fuel injectors for cyl 4 and the slightest amount in cyl 3. Injectors for cyl 1 and 2 looked clean. The plan is to clean all the injectors and see what happens.

[mooniac15u]

Did you do a mag check?

[AaronDC8402]

2 hours ago, mooniac15u said:

Did you do a mag check?

Yes. On the ground and in the air. Mag seems normal.

 

[carusoam]

1) Data is downloadable from the JPI.  

2) There may be a 1/8" port on your panel somewhere...  It will look like a headphone jack.

3) JPI supplies an RS232 cable that plugs into the 1/8" Jack.

4) the rs232 connects to any PC/laptop.  An RS232 to USB converter will be required for modern machinery.

5) graphing Software is downloadable directly from JPI.

6) Easy enough a GenX guy can do it. 

7) Newer engine monitors use a memory card to improve the process.

8) A wireless connection to the JPI would be an improvement. I haven't seen this yet.

9) Taking a screen shot and uploading to MS take extra steps...

All 90s technology still in use today.

Best regards,

-a-

[carusoam]

Stuff blocking fuel injectors...?

Sounds important to find out what is doing that.

There are screens upstream to be checked.

There is one source of polymer bits downstream of the screens.  Some old fuel lines have been known to shed their liners.

PP ideas only, not a mechanic.  Just stuff I learned on MS...

Best regards,

-a-