Mat Coch writes:

Uncertainty over how to enforce a ban on elaborate engine modes has forced the FIA to abandon plans to introduce new rules from this weekends Spanish Grand Prix.

Announced during the week, the sport's governing body said it would put a stop to the way teams run their engines before backtracking and stating the rule wouldn't be introduced after all.

By changing the engine mapping teams are able to force exhaust gasses under the car, even when drivers aren't using the throttle, thereby increasing the amount of downforce the car produces. "I think all the major teams are up to the same tricks with regards to engine mapping. Certainly we exploit them," admitted McLaren Engineering Director Tim Goss in the latest Vodafone McLaren Mercedes phone in.

"Since the middle of last season it's become quite apparent to journalists, and hence the rest of the public, that teams have been changing their engine map to get more out of exhaust momentum," he continued.

McLaren race engineer Phil Prew has previously suggested that some of Red Bull's advantage can be traced to the use of elaborate engine modes. Goss however is not so sure, though he believes when the new regulation is introduced all the leading teams will be affected. "It would be a performance set-back to us, I know it would almost certainly be a performance set-back to our major competitors," he admitted.

"I know what we get out of it," he continued, "and we get quite a substantial benefit. I imagine it would be quite a step-back for our competitors as well."

The initial decision to ban the use of complicated engine modes came as a surprise to the teams, Goss admitting that the matter hadn't even been discussed within the Technical Working Group. "I don't know whether they've taken it on themselves to clamp down on this, or whether they've been prompted," Goss said.

However, until the revised regulation is enforced the team is carrying on as usual, confident that it will be able to react to whatever the FIA ultimately decides. "We can react to whatever they tell us reasonably promptly," he said.

"For the moment it would appear that the FIA have decided it's quite a complex matter, and they need more time to consider how they will try and police it."