He repaid every penny with a last-minute header which levelled the scores to show the Posh are coming to terms with life in the Championship.
They might have won just one of their first dozen games after two promotions, but there was an easy confidence to their game.
It might have been very different after Bristol had gone ahead with a fine solo goal from Cole Skuse on the half hour.
City looked poised then to sweep ahead with a revised 4-3-3 line up looking as if it would end their record as one of the lowest scoring sides in their league.
But they overdid the high crosses into the box where they found themselves out jumped by central defenders Craig Morgan and Gaby Zakuani.
Still, City looked like controlling the final quarter of an hour but were undone by a goal which carried a big slice of luck Posh had earned.
From way out on the right, Danny Rose lifted a high ball on to Boyd who skimmed it off the back of his head towards the six-yard box.
There was more power on it than he though and as he wheeled round his saw it flying high into the top left-hand corner.
Earlier he had twice been close to setting up a goal for Craig Mackail-Smith, whose speed on the counter attack was always a worry to the Bristol backline.
In the first half before City's goal he had lured central defender Louis Carey forward before slipping a pass through to Mackail-Smith.
In the home goal, Dean Gerken won the one to one with a late response but that was nothing compared with the stunning save he made in the second half to the same combination.
Posh were pressing hard for an equaliser and a goal had looked odds on with Mackail-Smith surging clear off City's backline but somehow the keeper got a leg to the shot.
That had looked the hot spot of Posh's determined battle to avoid a seventh defeat.
Instead with Boyd's goal they left with their fifth draw while City can only look for consolation to Skuse's solo run which carried him past three defenders before he delivered the ball to the bottom left hand corner.