Rich,
I'm sure you've made sure your gas and filters are clean and fresh.
Look at the fuel pressure to check the regulator is correct.
I just took a 914 down to Lockwood. The engine would only come to 34
inches of MP but ran perfectly smooth. Trouble shot the sensors,
electrics and computer, all was fine. Dean had me check for the rubber
seals from the airbox to the carbs as that screws up the works. No air
leaks or cracks. On final inspection, it seems the carb diaphram and
piston were hanging up on one carb. I always believed that would result
in a rough running engine. Go figure. Kerry rebuilt both and all was
well. In the last 5 years I'm sure you put in the gasket kit in your
carbs. Please check them. The dual manometers work well in
troubleshooting the carbs, but this malfunction hardly showed up. Three
weeks of on and off shop time out of my life and 200 miles of trucking
this thing.
As for the Turbo. If the waste gate sticks closed you would see it in
low MP. If stuck open you will see an overboost (not good). If the
waste gate does not work smoothly, that can cause a surge in the engine
as you go to full turbo. Picture the servo pulling the cable to adjust
the targeted boost pressure commanded by the computer and throttle
position. In the process the computer command goes to the preset servo
movement and on a hot day, overshoots a little and it begins releasing
pressure, then the arm sticks, the servo tries to loosen the cable more
and then vibration loosens the arm causing a drop in pressure, the servo
corrects again and results in a surge. Then the servo really starts
hunting. Hitting the reset switch works to stabilize it if it is a
minor sticking problem above the 100% throttle position normally.
Surging at 60% indicates the tubo arm may be sticking as it starts out
commanding 100% (cable extended) then slowly reduces the servo position
to about 40% (1/4 throttle or so) then up to 88% at full turbo with the
engine off. look to see that the cable moves smoothly and the waste gate
is not hanging up.
Otherwise, I am out of ideas.
Bud
Custom Flight Creations
----- Original Message -----
From: TheSchultzFamily<mailto:Theschultzfamily@comcast.net>
To: europa-list@matronics.com<mailto:europa-list@matronics.com>
Sent: Tuesday, June 16, 2009 8:42 PM
Subject: Europa-List: Turbo problems???
<Theschultzfamily@comcast.net<mailto:Theschultzfamily@comcast.net>>
Time for some group input. I was bad and did not fly for about 6
weeks. I
went out to the airport with good intentions to rectify that problem
only to
find that above 60% power the engine would surge. I traced the problem
to a
stuck waste gate. I have since freed it up with a little mouse milk on
the
arm and the TCU servo and response to throttle seem to be good. The
problem
I am now having is at about 60% power the engine starts to surge and
trying
to go to full power just kills the engine. I "assume" it was turbo
related
and pulled the air filter to check the turbo. The blades seem to turn
fine.
A restart of the engine and all was good for about 2 days and then on
run up
the problem returned. I can't seem to shake the feeling that I still
have an
airflow problem but not sure how best to trouble shoot this one. Any
suggestions? I will be going back out tomorrow night to do a full
power run
up with the plane tied down. I have monitored and logged the engine
data but
it really just shows what you would expect with a surging engine.
Change in
RMP change in Airbox pressure.... The engine has 180 hours on it and
runs
great when it runs. Has anyone shot the inside of the turbo with a oil
to
break up any carbon build up? I am trying to get a camera scope to
have a
peek inside from the exhaust side.
Regards,
Rich Schultz
N262AE
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