Fabi would return to Indy car racing in 1988 with Porsche Motorsports in their #8 Quaker State March 88P-Porsche Indy V8. Despite the setbacks Fabi would get a best finish of 4th at the Bosch Spark Plug Grand Prix at Pennsylvania International Raceway. Fabi's return to the Indianapolis 500 was also disappointing as Fabi qualified 17th and finished 30th after losing a wheel after 30 laps. Fabi would finish the season ranked 10th in points with 44 points.
In 1989 Fabi would return with Porsche Motorsports in the #8 Quaker State March 89P-Porsche Indy V8. At the Indianapolis 500 Fabi qualified in 13th place and again finished in 30th place after retiring due to ignition problems after 23 laps. At the final two races of the season, the Firestone Indy 225 at Pennsylvania International Raceway and the Champion Spark Plug 300K at Laguna Seca Raceway, Fabi would retire due to handling issues at Nazareth and a crash at Laguna Seca. At the end of the season Fabi finished 4th in points with 141 points.
Fabi would return with Porsche Motorsports in 1990 to drive their #4 Foster's/Quaker State March 90P-Porsche Indy V8. In January Porsche's competitors voted against the use of the car and as a result Porsche had to use year-old March 89P chassis. Fabi would manage to qualify 7th at the Toyota Grand Prix of Long Beach on the Streets of Long Beach and would finish 10th. A new March 90P would start being used at the Indianapolis 500 and Fabi would start in 23rd place and retire in 18th place due to transmission problems after 162 laps. In the race Fabi crashed after 7 laps and finished in 27th place and also led for one lap.