Ipswich keeper Kelvin Davis was called into action twice in the opening two minutes, first when Michael Doyle nodded the ball through for Stephen Warnock, whose 12-yard effort Davis could only tip over.
From the resulting corner Doyle tried his luck from distance and forced a good low save from the unsighted Davis.
Doyle was involved again on seven minutes when he met Bjarni Gudjonsson's cross but his header was well wide.
Ipswich survived the initial onslaught and came back into the match when Jim Magilton crossed from deep for Martijn Reuser, but the Dutchman's header did not trouble Gavin Ward.
The City keeper was called into action minutes later, though, when Magilton hit a firm volley from 25 yards, the save was easy as a slight deflection took the sting out of the shot.
Both sides laboured and neither looked like scoring, until Coventry broke the deadlock in first half injury time through Warnock.
The on-loan Liverpool man nipped in to sweep home the rebound when George Santos blocked Julian Joachim's shot.
Half time substitute Darren Bent missed a glorious chance to equalise on 55 minutes when he ran onto Reuser's mis-hit shot but skewed the ball high and wide from a tight angle.
But they found an equaliser three minutes later when Shefki Kuqi capitalised on a defensive mix-up to chest the ball to substitute Westlake who smacked the ball in off Calum Davenportâ€™s shin.
Kuqi should have claimed the victory for Ipswich when Mo Konjic missed Reuser's cross, but the Finnish international scooped the ball over from close range.