whiskytango

TCM TSIO360-LB Throttle sensitivity

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I just had the engine overhauled in my 231.  I have the Merlyn UDC, GAMIs and it is intercooled.  I have noticed that it is difficult to set a desired MP compared to pre-overhaul performance.  I don't have a vernier throttle, but feel that it is almost essential now to be able to set a desired MP without significant overshoot and undershoot.  What could the engine overhaul shop and/or installer have changed to cause such a change in throttle response?

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Was the Merlyn overhauled as well? Not much else it could be outside of throttle rigging. But make sure from your downloaded data that the MAP is fluctuating and not unstable FF leading to MAP fluctuations if that makes sense.(I.e. not being caused by unstable FF)


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I experience a similar behavior. After a Merlyn overhaul last year if I do a full throttle takeoff I get a significant increase in MP shortly after takeoff. It is now really difficult to control the throttle.
That has not been the case before...

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If there are leaks in the tubing to or from the Merlyn, it becomes more unstable than before the Merlyn was installed.   Or time for an overhaul of the Merlyn?  I have a spare one on the shelf if you want to minimize downtime?

Aerodon

 

 

 

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20 minutes ago, Emmet said:

Interestingly the problem occured after the Merly overhaul ...

Agreed, which suggest  possible re-installation issue such as a leaky pneumatic hose that feeds the UDP to the wastegate or other rigging issue. But behaviour is like a sticking wastegate which can also come from a leaking UDP connection as @Aerodon mentions above.

50 minutes ago, jetdriven said:

The problem is called bootstrapping.  

Its like bootstrapping, but technically speaking, bootstrapping occurs when the compressor is at maximum output with the wastegate fully closed and and the automatic control system is no longer able to maintain constant UDP. Because the system becomes unregulated we'll see large MP variations. Proof that  bootstrapping is occurring is shown by seeing it clear with another 50+ rpm.

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