Hispania threatened to protest next weekend's showcase Monaco Grand Prix after writing to Formula One's governing body on Sunday to demand an immediate ban on controversial engine mapping and exhaust systems.
Principal Colin Kolles had warned before the Spanish Grand Prix that his team could protest that race but in the end decided to hold fire.
"We wrote a letter to the president of the FIA (International Automobile Federation) to ban the exhausts immediately because they are against the regulations," he told Reuters.
"The letter went already, it's signed."
Asked whether they could protest in Monaco, he replied: "If there is no change, we have no other choice I think. I'm obviously expecting a response before next weekend's race."
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FIA race director Charlie Whiting told reporters on Friday that the governing body was concerned about engine maps that give an aerodynamic advantage by ensuring a constant flow of exhaust gases through the rear of the car even when a driver lifts off the throttle.
The FIA had planned an immediate ban before Barcelona but then delayed action until a meeting of the technical working group after Monaco.
All of the 12 teams, with the exception of Virgin Racing and Hispania, are using the systems.
Kolles was seen talking intently to Whiting on Sunday morning in the Barcelona paddock.
"When you have a blown exhaust, and you are on full throttle, it blows into the diffuser and you have more downforce," explained the Germany-based team boss.
"But now the blown exhaust went to a different stage where you use gases, hot gases, off-throttle.
"So you are influencing by your foot, the aerodynamics. And not only by the use of your foot, the valves and pistons inside the engine. They are moving, and you are not allowed to use anything that moves to influence the aero. It has to be all fixed."
Spanish-based Hispania made their Formula One debut last year and have yet to come close to scoring a point. Their drivers this year are Indian Narain Karthikeyan and Italian Vitantonio Liuzzi.
Liuzzi failed to finish in Barcelona while Karthikeyan was 21st and last, five laps behind Red Bull's winner Sebastian Vettel.
