Their cars were found to have radiator pans which were unapproved and heavier than normal, during the post-qualifying technical inspection last Friday.
As a consequence, both drivers have been docked 50 points in the championship, plus their car owners have also been deducted the same amount in the owners' ranking. Ambrose drops from 26th to 28th place in the standings, while Papis falls one spot from 37th to 38th.
Their crew chiefs Frank Kerr and Robert "Bootie" Barker have been fined $75,000 and placed on probation until the end of the year.
"While the penalty feels excessive for an apparent misunderstanding on submitting a part, we also understand NASCAR has to police the sport and rule strictly to keep a level playing field among the teams," said Tad Geschickter, owner of Ambrose's car.
"We will work diligently to ensure that there are no misunderstandings in the future. We are focusing our energy on turning our season around and winning races."
NASCAR has also announced penalties for both Michael Waltrip Racing teams, the #00 of David Reutimann and the #56 of Martin Truex Jr, for using unapproved parts.
Cal Wells, the team's executive vice president said their infringements are a consequence of a misunderstanding on whether the parts in question needed to be submitted to NASCAR for approval.
"NASCAR indicated we were running a part which had not been officially submitted for approval," Wells said. "We accept NASCAR's ruling and will not appeal because we cannot debate whether the part was submitted, only whether or not the part needed submission.
"This gives us a clear line of sight on how parts need to be submitted for approval. We will work diligently with NASCAR in the future on all new parts to ensure this does not happen to MWR again."
Rodney Childers, crew chief of the #00 team, and Pat Tryson, crew chief of the #56 team, have each been fined $25,000 and placed on probation until the end of the year.
Although Papis and Ambrose drive for Germain Racing and JTG Daugherty Racing respectively, their teams are technically affiliated to Michael Waltrip Racing.
Real play down Barca visitBurton leads second spoiler test
