ROLLING MEADOWS, Ill. (AP) _ A 14-year-old boy died in a closed garage after reading about six teen- agers who committed suicide by inhaling auto exhaust, but family members contend he was the victim of an experiment that ''got out of hand.''

However, the physician who performed the autopsy termed the death a suicide.

Newspaper clippings about two recent group suicides were discovered under Kevin Pyter's bed after his body was found in the family's closed garage Saturday night, said police in this northwest Chicago suburb.

''The family feels this was an accident, not deliberate. We are afraid of a ripple effect on other teens,'' said a woman who answered the telephone at the Pyter home Monday. She would identify herself only as a relative of the victim.

''His mother contends the boy didn't intend to take his life because she thought everything was going smoothly,'' said Robert Hoese, principal of Rolling Meadows High School, where the boy was a freshman.

''She feels it was an experiment that got out of hand. He read about the other suicides and thought he could beat things like that. But it got of hand,'' Hoese said.

Kevin's mother, Marilyn Pyter, found his body on the roof of her station wagon as she and a friend were on their way out to dinner, said Sgt. Douglas Larsson.

An autopsy determined the death was a suicide, said Dr. Edmund Donoghue Jr., who performed the examination.

''He died of carbon monoxide intoxication, due to the inhalation of auto exhaust fumes,'' Donoghue said Monday night. ''From the evidence, it was intentional. The engine had stopped running by the time the boy was found, but the ignition was still turned on.''

Donoghue said carbon monoxide from a running car engine in a closed garage would reach lethal levels in from 10 minutes to 20 minutes.

Last week, two groups of teen-agers committed suicide by closing themselves in idling cars. Four young people killed themselves in New Jersey and, a day later, two girls died in a south Chicago suburb.

''Some say the press overplays it (teen-age suicide), but I don't think so,'' Hoese said. ''Parents have to know about it. We don't know what goes on in their minds. It's really frightening.''

The boy left no suicide note, and Hoese and others interviewed by police said he appeared in good spirits.

''He was a very nice boy, very nice and never trouble,'' said neighbor Sophie Plantaz, who added that Kevin had a paper route.

''He was an average student, an average wrestler on the freshman wrestling team and an average instrumentalist in the concert band,'' Hoese said. ''I met this morning with his counselor and his teachers, the school's social worker and psychologist. They had no inkling.

''He seemed so happy-go-lucky,'' he said.

''It defies all logic. He wasn't depressed. He was doing all right,'' Hoese said.

He said Kevin's 16-year-old sister, Nadine, now in Australia on a student- exchange program, helped counsel troubled students at the high school.

''Some kids won't talk to grownups, so we have a peer counseling program,'' Hoese said.

Funeral services were held Monday in Alsip for Nancy Grannan, 19, and Karen Logan, 17, who committed suicide last Thursday by sitting inside a car with the engine running inside the Logans' garage.

On Wednesday, four teens in Bergenfield, N.J., died after locking themselves in an idling car in a garage

Reseachers say about 15,000 young Americans between the ages of 10 and 24 kill themselves each year.