No cars had set a flying lap by the time the first incident occurred, as FP1 pacesetter Kyle Kirkwood was struggling with the brakes on his AJ Foyt car.
After he let David Malukas by on his outside at Turn 7, he couldn’t slow down sufficiently and went back down the inside of the bemused Malukas, but his former Indy Lights rival hadn’t spotted him and the pair made wheel-to-wheel contact, to see Kirkwood slide head on into the tyre barrier and Malukas went down the escape road.
At the restart Romain Grosjean of Andretti Autosport was the first driver to set a representative lap time of a 1m16.7467s, followed by a 1m16.3981s with 30 minutes to go.
At that point, it put him 0.666s ahead of the next fastest driver Simon Pagenaud for Meyer Shank Racing, as Josef Newgarden sprung his Team Penske into third just before the red flag fell for Jimmie Johnson spinning as he left the pits.
Once he’d been bump-started, Pagenaud trimmed his deficit to Grosjean down to 0.31s, and Pato O’Ward inserted his Arrow McLaren SP into third.
Then Dalton Kellett’s Foyt car struck the Turn 14 wall hard, bringing out the third red flag of the session. As everyone switched to alternates, Will Power spun his car exiting Turn 11, kept it off the wall but stalled, so out came another red flag.
Simon Pagenaud, Meyer Shank Racing Honda
Photo by: Phillip Abbott / Motorsport Images
When the session restarted, Pagenaud and Castroneves created an MSR 1-2, with Pagenaud being first driver into the 1m15s, until their semi team-mate Alexander Rossi went top with a 1min15.8101s.
But then Pagenaud suddenly stopped on track late into the session, which effectively ended FP2 early with no further improvements, to see Rossi take top spot from Pagenaud and Newgarden.
With Castroneves in fourth, Malukas landed in fifth ahead of Scott McLaughlin and Felix Rosenqvist as he bounced back from a crash in Friday’s opening practice session.
IndyCar Detroit GP qualifying will start at 12.35pm local time (5.35pm BST).
IndyCar Detroit GP – FP2 results