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Not enough power on rotax 914

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Posted (edited)

hi. I have a problem. because Cavalon has not enough power. when i check during the take off time. that time Engine RPM 5500 and Manifold pressure was 30 . it must  RPM 5800

Manifold pressure 35. my mind is manifold is so dirtied or turbocharger is working half.
i cleaned turbocharger and carburetor . pls help me how am i fix it

Edited by Bilguun

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Posted (edited)

Bilguun, do you have access to the Heavy Maintenance Manual for the Rotax 914? Here is the link to the HMM.




Your 914 turbocharger and wastegate is controlled by an electronic regulator (sometimes called a CPU - Central Processing Unit, other times called an ECU - Electronic Control Unit).


Rotax call the 914 electronic regulator, a TCU (Turbocharger Control Unit). The TCU takes information from several sensors located around the engine, and processes this information to control the turbocharger and the wastegate.


The initial requirement is to ensure the throttle is positioned correctly, and the wastegate control mechanism is similarly correctly positioned. Section 76-00-00 of the HMM gives all the information you require.

If the Throttle Position Sensor is feeding incorrect information to the TCU, there will possibly be a lack of power.


Note that because the TCU is an electronic controller, it logs faults, as well as many other engine parameters.

This information can be extracted from the TCU by the use of a computer and the necessary TCU interface, which is proprietary Rotax software (that is, you cannot use any other software or program).

This interface is called the "communication program" by Rotax. It comprises software, and also a dongle for some models of the TCU. Section 76-00-00 outlines what is required (pages 13 and 14).


I'd suggest you check the TCU log via the Rotax interface, on a computer, and see if the TCU has logged any engine faults associated with the turbocharger and wastegate, and any other engine controls or sensors.

Edited by onetrack
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I had a problem with what I thought was a turbo wastegate control on my 4WD.

It went into a garage for work on the brakes and I asked the mechanic to have a quick look at the waste gate operation. He couldn't see anything wrong but didn't remove anything to get a real good look. I then looked and found a plastic bag, partially blocking the inlet. So have a look at the air cleaner and inlet. 

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