Diesel, 46, explained on Facebook earlier this week that he and Walker used to go over scenes together and make sure they were quality.
"There wasn’t a scene in the saga he didn’t want to discuss, improve... even with just a changing of a line or adding a specific nuance to enrich a moment," Diesel wrote. "He did it with the pride of knowing, that over a decade of portraying Brian, through four directors, multiple writers and new producers he was able to maintain the inner core of the character he created. Those work ethics and drive to be both truthful, and in his own way, evolve the decade spanning character is what made his character as iconic as it has become."
Diesel said Walker always knew he "would fight for him."
"Whether it was to protect his deal or to protect his integrity… and he knew that if it made for a better film, I was going to do whatever it took… it is why together, we won best duo... twice, 12 years apart," he added. "With our new ambitious vfx team, the whole cast and crew has had to adjust to this awkward and uncomfortable process of pixels over people."
He closed by saying the challenege "is not to allow it to compromise what makes the character so special."
Diesel followed up with another post yesterday that ended with "Making Pablo proud..."
In addition to visual affects, Paul Walker's brothers Caleb and Cody were tapped to help finish "Fast & Furious 7."
An announcement a few months ago read, ""Paul had already shot his dramatic scenes and most of his action for FAST & FURIOUS 7, and it’s among the strongest work of his career ... We have resumed shooting and now welcome Paul’s brothers, Caleb and Cody, into our FAST family. Caleb and Cody are helping us complete some remaining action for their brother and fill in small gaps left in production. Having them on set has made us all feel that Paul is with us too."
Walker died on Nov. 30 last year after the Porsche he was a passenger in lost control and crash near a charity event for his organization Reach Out Worldwide.