Rebecca R Gopalan, the woman, died on the spot.
The incident took place on Sunday.
The woman's 29-year-old son Rohan R Gopalan fell unconscious during the suicide attempt and was being treated at a hospital at present, police said.
"Heavily in debts, the mother-son duo decided to end their lives. Rohan attached a pipe from silencer of his scooter to the bedroom and released the fumes by starting the vehicle. As the room got filled with fumes, the old woman died of suffocation," said Rajesh Wagh, an officer of Palghar police station.
Rohan told the police that he got the idea of ending the life this way from a Hollywood film.
Further probe is on.