Renault's Fernando Alonso will struggle to make the top 10 on the grid for the Hungarian Grand Prix after picking up a two-second qualifying penalty.
Alonso was punished for a deliberate brake test and for overtaking under a flag in Friday's second practice.
It is another blow for Renault who are not enjoying the best of weeks.
The French team, so dominant earlier in the season, had already scrapped their plan to use a "mass damper" considered crucial to their cars' performance.
The new design was banned by the FIA before last week's race in Germany only for the race stewards to pass it as legal.
Renault had intended to use the "mass damper" - a counterweight mounted on springs within the nose of the car - in Hungary but were forced to change their minds when it became clear that the FIA still considers the stability-aid to be illegal.
World champion Alonso, who has seen his championship lead shrink from 25 points to 11 in just three races, struggled last Sunday without the system.
By contrast, rival Michael Schumacher won his third straight grand prix and with six races to go is back in contention for an eighth world title.
The Ferraris have shown well in practice in Hungary and Schumacher could slash the lead still further if Alonso is stuck down the grid on a track where it is hard to overtake.
Alonso was docked one second for overtaking when yellow flags were waved to indicate a hazard towards the end of Friday's practice.
And he was penalised a further second after an incident with Red Bull test driver Robert Doornbos.
Alonso gesticulated angrily at the Dutchman after being held up on the start-finish straight. He weaved ahead and then slowed dramatically at the apex of the corner, forcing Doornbos to take avoiding action, a move the stewards interpreted as a brake test.
Alonso claimed he was just reminding Doornbos to use his mirrors but the stewards said his actions were "unnecessary, unacceptable and dangerous".
Earlier, a Renault spokesman said the team had "reconsidered" its decision to use the "mass damper" following a communication from the FIA explaining why it thought it was illegal.
The spokesman added that the team hoped they would not be as far off the pace in Hungary as they were in Germany.
"That was more down to tyre wear at Hockenheim," the spokesman said.
Renault learned before the German race that they would not be allowed to use the system, which they pioneered last season and which has subsequently been adopted by six other teams.
The FIA said it considered the system to be illegal because it helped the cars' aerodynamics.
But the FIA's race stewards in Germany then passed the system as legal - only for FIA bosses to say they intended to lodge an appeal against that decision.
As that appeal will not take place until after this weekend's race, Renault felt they could not risk running the system in Germany as they could have subsequently lost any points they scored if the FIA won its appeal.
But the FIA indicated after the German race that it would not seek to retrospectively punish any team using a "mass damper" if its appeal was successful.
That initially seemed to convince Renault to use the system in Hungary but a subsequent letter from FIA race director Charlie Whiting changed their minds.
Renault were hurt by the ban more than other teams because their entire car was designed around the system, whereas others had simply added it on at a later date.
nd the blow is even worse because F1 is in the middle of a ban on testing, which means the team cannot try out ways of improving the car other than at races, where track time is limited.
Engineering boss Pat Symonds admitted the team's performance was harmed by not running the "mass damper".
He said after the German race that "it goes without saying that removing it degraded our performance, otherwise the component would not have been on the car throughout the season.
"After using the device for the first time in the final races of 2005, the design and development of this year's car was optimised with it in place.
"The ride and the behaviour over kerbs of the R26 at the last race was certainly not as good as we have been accustomed to this year. But there were other factors at work as well."
Renault also struggled with tyre blistering, which was almost certainly worsened by not using the "mass damper", but they are hopeful that a new tyre for Hungary will solve that problem.
The team will also continue with a new aerodynamic package that was introduced in Germany, where its effectiveness was limited by the team's other problems.
Renault are facing a tough task holding on to their lead as Ferrari's tyre supplier Bridgestone has appeared to have an advantage over Michelin in the last three races.
