The sound on my FSX program is very poor, especially engine sound. All other sound from other sources comes in loud and clear.
Is it possible, or recommended, to run the installation disk over the top of the existing installation?
When I am flying online with others in our group, the Teamspeak voice sound is fine, but the engine sound is almost non-existant or very poor.
Most likely a screwed up sound file. Maybe try taking another sound file from another aircraft and see if it works then. Or try getting a sound addon from TSS, or freeware.
You can also run the main installation disc and just do a repair of your previous installation.