Rangers had to come from a goal behind when Grant McCann scored in the 8th minute for struggling Scunthorpe.
The equaliser came just before half time from a Martin Rowlands penalty. Rowan Vine was brought down in the box and Rowlands slotted home the spot kick.
Patrick Agyemang and Rowan Vine then won the game for Q.P.R. in the final 11 mins.
Rangers are looking up for an unlikely play off place. Scunthorpe are looking more likely to be joining Colchester on their way out of the Championship at the wrong end.