New York- Threatened with perjury charges, a Bronx firefighter changed his story yesterday – and described how he and two co-workers had sex with a troubled woman at their firehouse, sources said.

Tony DeLuca, 34, recanted denials and said the firefighters took turns having sex with the woman at the so-called Animal House in Morris Heights last week, the sources said.

He said Christian Waugh, 30, and Anthony Loscuito, 27, had sex with the Staten Island woman “separately in that small room,” DeLuca told investigators, said an FDNY official.

Loscuito is expected to admit to the disgraceful encounter when he talks to investigators again today, sources said.

The development came as Fire Commissioner Nicholas Scoppetta read the riot act to fire commanders and ordered a citywide, by-the-book crackdown on firehouses that will include surprise inspections.

The Fire Department plans to fire everyone involved in the sexcapades, one of worst scandals to tarnish the Bravest in years.

DeLuca, who is married and lives on Long Island, and Loscuito were facing possible criminal charges because they allegedly lied when city Department of Investigation officials first questioned them. They agreed to recant after DOI threatened to turn the case over to prosecutors, officials said.

Waugh invoked the Fifth Amendment when asked about the night of debauchery at the Engine 75/Ladder 33 firehouse, sources said.

The 34-year-old woman first claimed she was gang-raped, then admitted she willingly had sex with the men after meeting DeLuca through an Internet chat room. The woman, who recently committed herself to a psychiatric ward, later returned to the rape account.

The Daily News revealed this week a steamy trail of E-mails sent to and from the home computer of the woman, who has a history of mental problems and had bragged about having sex with hundreds of firefighters and cops since 9/11.

Meanwhile, Scoppetta and Chief of Department Pete Hayden summoned 30 top chiefs and borough commanders to FDNY headquarters in Brooklyn.

They ordered a wide-ranging crackdown on violations big and small – from girlie pictures taped on lockers to drinking in firehouses.

“We’ve kind of been lax,” said one FDNY official.

Scoppetta ordered chiefs to mount an extensive program of inspections at the city’s 220 firehouses, including surprise dead-of-night visits from borough commanders.

Firefighters also will be ordered to strictly abide by all rules and regulations, including tight curbs on visitors and bans on unapproved shift swapping.