According to this news article it is going to run 4 days a week

LOCO LINK ERODE WAP-4 FOR BOTH TIRUPATHI COIMBATORE EXPRESS AND YESWANTPUR TIRUPATHI EXPRESS.

ADDITIONAL STOPPAGES FOR COIMBATORE – TIRUPATI – COIMBATORE EXPRESSES AT ERODE AND TIRUPPURDue to persistent demands from rail users, T.No.12758/12757 Coimbatore – Tirupati – Coimbatore Tri-weekly Superfast Expresses will stop at Erode and Tiruppur on an experimental basis for a period of six months w.e.f. 13.2.2011 ex. Coimbatore and 14.2.2011 ex. Tirupati.T.No.12758 Coimbatore – Tirupati Tri-weekly Superfast ExpressTiruppur arr/dep. 06.40/06.42 hrs.Erode arr/dep. 07.25/07.30 hrs.T.No.12757 Tirupati – Coimbatore Tri-weekly Superfast ExpressErode arr/dep. 20.35/20.40 hrs.Tiruppur arr/dep. 21.23/21.25 hrs.