Richard Pacquette struck in the 92nd minute to earn Rangers a point they looked unlikely to get at one stage.
The super sub was set up by a mis-hit ball which he cracked home left-footed from 18 yards.
Plymouth could only kick themselves after going two ahead, but in truth their attacks were few and far between.
Rangers had all the first-half possession before Argyle grabbed the all important goal.
Up until David Friio's strike, the Plymouth final third had been under seige, but dispite all their pressure Rangers failed to find a killer ball.
The home club's best chances came within a minute of each other. Kevin Gallen made space for himself on the edge of the box and his right-foot curler needed a full stretch drive from the keeper to turn the ball away.
From the resulting corner Tommy Williams got the ball back and fired low to bring a second fine save out of Romain Larrieu.
After 33 minutes, a high bouncing ball in the Rangers box was left to bounce before Friio brought it under control, stepped inside one player and shot low and in off the far post.
It was much the same pattern for the first ten minutes of the second half with QPR pressing forward and Plymouth attempting to launch counter attacks.
On 58 minutes, an unmarked Micky Evans shot low from 11 yards but found Simon Royce saving well and scrambling the ball to safety as Friio rushed in.
Royce's respite lasted all of a minute.
From the corner the ball fell kindly to Lee Hodges whose left-foot shot was good enough to dribble through the legs of Tom Williams on the line It looked all over but Jerome Thomas set up a rousing finish with a fine left-foot strike form inside the box just as Rangers fans were about to leave early.
Gallen then had a goal bound shot locked but there was no-one to get in the way of Pacquette's thunderbolt to bring the fans to thei seats.
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