Michael Egan has been waiting with rising impatience for the Pontiac J2000 subcompact he ordered in May from a Maryland dealer. He is one of thousands of frustrated car buyers who want versions of the new General Motors Corp. J cars but have yet to see them.

GM hasn't volunteered an explanation for that specific delay -- Egan received conflicting explanations from various Pontiac and GM officials -- and it took a series of telephone calls up the company's chain of command to find the answer.

But the significance of Egan's problem may be that at the top levels of the company, GM doesn't sound embarrassed about the delay. In a way, it's proud.

In June, GM abruptly halted production of the J2000 model Egan ordered after only 1,407 cars had been turned out. GM officials felt the cars weren't operating well enough because of a problem with a small but critical engine component. Production didn't start again until yesterday, when GM was satisfied the problem had been solved, a company spokesman said.

Today, with quality a sink-or-swim issue for GM and the rest of the U.S. auto industry in its battle with the Japanese auto manufacturers, GM would rather fall far behind normal production schedules and risk the anger of consumers and its own dealers, if necessary, rather than produce a car it has to apologize for later, spokesman Bruce McDonald said.

"We are behind where we should be" in J car production, GM Vice Chairman Howard H. Kehrl said in June. "But we have made the point that we want good parts. We have deliberately set very high standards."

The problem with Egan's J2000 illustrates the challenge Detroit is facing as it tries to get back on its feet after more than a year of disastrous losses.

Egan, a Bell System employe from Maryland who uses his car for business, had ordered a special version of the J2000, featuring a four-speed manual transmission and air conditioning. Simply put, the "brain" that controls engine operation on that J2000 model wasn't working adequately.

Like most GM cars, the Pontiac J2000 is equipped with a Computer Command Control system designed to produce the best gasoline mileage while meeting the Environmental Protection Agency's pollution-control standards.

The system depends on a small digital computer that works this way, according to GM: "Information on engine coolant temperature, engine speed, carburetor throttle blade position, intake manifold pressure and the amount of oxygen in exhaust gases goes to the computer. This information is analyzed in milliseconds and the computer sends out messages in the form of electrical impulses" to the engine and other parts of the auto's power system."

The carburetor operation, for instance, may be fine-tuned 10 times a second by electrical impulses from the computer to assure that the mixture of air and gasoline is precisely controlled to produce top mileage and minimal polution.

Each J-car model has a computer chip programmed according to the specific engine and options on the car.

For some reason, the chip in the J2000s with four-speed manual transmissions and air conditioning produced unsatisfactory performance -- probably an unacceptable loss of power when shifting gears with the air conditioner on, McDonald said.

Problems with the computer systems in new cars are common. It took GM from June until last week to correct the difficulty with the J2000 and produce enough new chips to get that model back into production, McDonald said. Production began yesterday in GM's Lordstown, Ohio plant.

Other problems hav made for a "horrendous" start up for the J car, according to Ward's Auto Week, an auto industry journal.

For months, most GM dealers have had only had a handul of J cars show. As of last week, GM had produced an estimated 89,539 J cars -- 45,562 Chevrolet Cavaliers, 34,982 J2000s and 8,995 Cadillac Cimarrons, a very slow beginning by normal standards.

It will take another two months before J car stocks are sufficient to test its true appeal. But spokesman McDonald says there is no second-guessing at G.M. In the past, the J2000 problem would probably have been dealt with by trying to alter the tuning after the car was built, McDonald said. "This definitely reflects a different attitude. If it isn't right, we're prepared to say, 'Time out. This isn't what we want.'"