The Wanderers boss is desperately seeking new additions after seeing a steady stream of players depart the Reebok since the close of the season.
Matt Taylor's £2.2million move to West Ham has left Coyle with just 15 outfield players and the Scot has been tipped to raid former club Burnley for midfielder Eagles and defender Mears.
Some reports have claimed Bolton have seen a £3million bid accepted by the Clarets but Coyle would not be drawn on his targets, although he admits he wants at least three new faces before the transfer window closes.
He told the Bolton News: "We're still looking to add to our squad and to bring three or four players into the group we've got.
"I don't want to get drawn into it [who we're trying to sign] until I've got the nuts and bolts nailed down with players but there are some good players out there and we are trying to get them to the club.
"You always need to tick a number of boxes for that to come to fruition but we're doing everything in our power to try to bring in quality players to help the squad that we have."
Coyle was linked with Onuoha earlier in the summer as a possible makeweight in a deal involving Gary Cahill heading to Eastlands, but the deal failed to materialise.
However, the 24-year-old has been left out of City's tour of America and has been deemed surplus to requirements by boss Roberto Mancini.
Coyle is believed to be keen to make a move for the City man when the Wanderers return from their pre-season tour of the USA but he could face competition from Sunderland, where Onuoha enjoyed a successful loan stint last season.