What's new
Van's Air Force

The definitive Van's Aircraft support community! Buying, building or flying an RV? Join our exclusive family of mentors and enthusiasts!

Migrating high EGT, flow divider?

B

BruceW

Well Known Member
Sponsor
Diagnosis help requested . . . .
In the process of breaking in the #3 cylinder. Going fine, everything indicates good on the #3.
During one break in flight, the #1 cylinder started indicating high EGT.
Headed to base and inspected intake system suspecting an intake leak.
Replaced the intake boot and intake/cylinder gasket.
Tested, and EGT was still high.
Check compression, looked thru on borescope, fine and fine.
Cleaned #1 FI injector, tightened everything down.
#1 looked good on run up. Time for a flight test.

On shallow climb out, #1 was looking good.
But now #2 was showing high EGT. WTF?
And started running rough at either full rich or lean. Kinda smooth in the middle. Weird.
On decent, pulled power resulted in some exhaust popping. That usually says intake leak.
Landed, checked all intake bolts and boots on #2. Fine.

It appears to be a migrating high EGT, lean mixture. First #1 now #2.
I am sure intake is sound. Have torqued all items multiple times.

Now thinking fuel flow blockage, another kind of lean mixture.
Servo must be working OK since other cylinders are running fine.
Now wondering about the flow divider.
Dunno what's inside it, or what could go wrong.
Running an Aerosport IO-360-B1B with about 700 hours.
Precision Aeromotive FI system.

Thoughts/ideas appreciated.
 
BruceW said:
Diagnosis help requested . . . .
In the process of breaking in the #3 cylinder. Going fine, everything indicates good on the #3.
During one break in flight, the #1 cylinder started indicating high EGT.
Headed to base and inspected intake system suspecting an intake leak.
Replaced the intake boot and intake/cylinder gasket.
Tested, and EGT was still high.
Check compression, looked thru on borescope, fine and fine.
Cleaned #1 FI injector, tightened everything down.
#1 looked good on run up. Time for a flight test.

On shallow climb out, #1 was looking good.
But now #2 was showing high EGT. WTF?
And started running rough at either full rich or lean. Kinda smooth in the middle. Weird.
On decent, pulled power resulted in some exhaust popping. That usually says intake leak.
Landed, checked all intake bolts and boots on #2. Fine.

It appears to be a migrating high EGT, lean mixture. First #1 now #2.
I am sure intake is sound. Have torqued all items multiple times.

Now thinking fuel flow blockage, another kind of lean mixture.
Servo must be working OK since other cylinders are running fine.
Now wondering about the flow divider.
Dunno what's inside it, or what could go wrong.
Running an Aerosport IO-360-B1B with about 700 hours.
Precision Aeromotive FI system.

Thoughts/ideas appreciated.
Click to expand...
If one spark plug in a cylinder does not fire, unburnt fuel may burn in the exhaust and this will present itself as high EGT.

Good luck
 
Yes. A piece of junk in the flow divider can move around and block various ports. Seen it happen.
 
Thanks for the replies. Is the flow divider a builder serviceable item? Or a send in to Precision airmotive?
If the former, where to find instructions for service?
 
BruceW said:
Thanks for the replies. Is the flow divider a builder serviceable item? Or a send in to Precision airmotive?
If the former, where to find instructions for service?
Click to expand...
Call Don Rivera at AirFlow Performance. He will tell you what to do.

Carl
 
BruceW said:
Thanks for the replies. Is the flow divider a builder serviceable item? Or a send in to Precision airmotive?
If the former, where to find instructions for service?
Click to expand...
Very easy to disassemble and clean. Just watch out for the spring under the cap. With the cap off, pull out the large diaphragm with the long rod and metering piston. Carefully check for debris in the four v slots and thoroughly clean the whole assembly.
 
You must log in or register to reply here.
Back
Top