Jennings finished with 21 points, and the Pistons beat San Antonio 109-100 on Monday night in Loyer's first game at the helm.
Detroit abruptly fired Maurice Cheeks on Sunday after only 50 games as coach, but although they've been unimpressive for the most part this season, the Pistons have played better lately. The comfortable win over the Spurs was Detroit's fifth in seven games.
"I told them it was going to be an emotional day," Loyer said. "I told them I thought we can play, collectively, for longer periods of time better than we have."
Rodney Stuckey scored 20 points for the Pistons, and Greg Monroe added 15 points and 10 rebounds.
Marco Belinelli led the Spurs with 20 points.
Detroit pulled even with Charlotte for the final playoff spot in the Eastern Conference, and the Pistons have shown flashes recently of the potential they thought they'd have this season. After signing Josh Smith and trading for Jennings in the offseason, Detroit is barely ahead of last season's pace in terms of wins and losses.
Jennings has been terrific lately, though. After scoring 35 points with 12 assists Saturday against Denver, he orchestrated another strong offensive effort Monday.
San Antonio, meanwhile, turned the ball over eight times in the third quarter, when Detroit pushed its lead from 11 to 20. The Spurs finished with 19 turnovers, giving the Pistons all the help they would need.
"We lost the game because we probably played the worst defense we've played all season, especially in the first half," San Antonio coach Gregg Popovich said. "We didn't bring it mentally or physically, and the Pistons did."
Loyer's sideline demeanor was quite a change from Cheeks' more calm approach. At one point, Loyer came all the way across midcourt to give instructions as the Pistons were trying to hold on.
"They're both two different coaches," Jennings said. "One is loud, the other one is kind of laid back. They're both great guys—especially Cheeks. He's like a father figure to me, so he's definitely going to be missed. But this is the NBA, so I know how that goes."
The Pistons went on a 12-2 run in the third to take a 73-52 lead, then added a few more highlights later in that quarter. Smith threw down a one-handed dunk after a turnover by San Antonio, and Jennings made a layup after Detroit's Andre Drummond blocked Aron Baynes' shot emphatically off the glass.
Jennings missed from the perimeter, then stole the ball near midcourt and went in for a three-point play to make it 84-62.
"I told the guys today, just when we were in the locker room, I'm so proud of them," Loyer said. "I only thought there was about a three-minute period where they showed more energy, more determination than us. You show determination, hustle for 45 of the 48 minutes, you're going to be pretty successful most nights."
San Antonio is in the midst of a nine-game road swing. Belinelli was back after dealing with back spasms, but the Spurs were without Manu Ginobili (left hamstring) and Kawhi Leonard (right hand).
The Pistons went on a 15-4 run in the second quarter, capped by a 3-pointer by Jennings that put them ahead 57-45.
"They played hard," San Antonio's Danny Green said. "They wanted to play with some passion and they got loose balls."
NOTES: The Pistons have won five straight at home after starting 7-15 at The Palace. ... After Cheeks' firing, Popovich was asked about the key to his longevity with the Spurs. "I have information on everybody," he joked. "And I've threatened everybody I'll let it out unless they keep me as long as I want to stay." ... Ginobili has joined the Spurs on this road trip, but he's not expected to play until after the All-Star break.