The Federal Trade Commission is expected to announce a "major consumer protection action" against Ford Motor Co., today.

The commission announced a press briefing would be held on such an action without naming Ford. But it is understood the subject will be Ford's problems with an engine flaw affecting some 2.7 million Maverick, Comet, Granada and Monarch compact cars and Pinto, Bobcat and Mustang subcompacts.

FTC sources indicated the commissions has issued a complaint against Ford based on its failure to notify individual owners of the affected cars of possible trouble with their engine and on Ford's program of paying for repairs if breakdowns occur.

Ford Motor Co. said it was holding negotiations with the FTC, but it isn't known whether such negotiations have produced a settlement between the agency and the company or whether the negotiations have broken down and the FTC merely will announce a complaint against Ford.

The engine problem occurs in very cold weather, preventing oil from reaching cylinder walls while the cars are still warming up. The result can be excessive engine wear that, according to Ford's estimates, can require $190 to $250 per car to repair. Althought a much larger number of cars could have the problem, Ford expects only about 2 per cent, or 55,000 cars, to develop serious engine trouble.

The cars are 1974 to 1977 Ford and Mercury models.