Mayor Michael Bilandic fired his commissioner of consumer sales yesterday and said he had taken a lie detector test which disproved her charges that he accepted a bribe or conspired to raise taxi fares.

Bilandic announced the firing of Jane Byrne, who last week accused him of helping "grease" the way for an 11.7 per cent cab fare hike approved in July.

Byrne had no immediate comment. She had taken a lie detector test at the request of the Chicago Daily News last week. The firm administering it said her responses to questions about the charges she raised in a memo registered as truthful.

Bilandic said he took the polygraph test Sunday at the offices of John E. Reid and Associates, the same firm that tested Byrne. He refused to answer questions, and left a news conference after reading a statement to reporters that announced Byrne's firing.

In her memo, Byrne said Bilandic designed a cover-up plan to pass the cab fare increase at an emergency City Council meeting. She quoted Bilandic as saying, "We won't make the rate increase the reason for the council meeming. We'll blow up some other matter to look important and quietly tack the increase on in unfinished business . . ."