Walkinshaw Andretti United, Grove Racing, and Tickford Racing (Cars #5, #56 only) make for a total of six Mustangs at the rural Victorian circuit in what is the final test day before the season starts in Newcastle on March 10.
All three of those teams were beset by throttle problems at the official pre-season test which took place exactly a week ago at Sydney Motorsport Park after a last-minute change to the Coyote-derived engine's calibration, as revealed by Speedcafe.com.
Click here to have your say on the state of Australian motorsport and go into the draw to win a Kincrome Tool Armour Workshop valued at $11,999.
As at approximately three hours into today's test at Winton, the Mustangs have run without any obvious sign of trouble.
“We've made a few small changes to the map we know that works very, very well and, so far today, we have not got any complaints whatsoever,” Rob Herrod, of Ford engine supplier Herrod Performance Engines, told Speedcafe.com at Winton.
“The report back from every driver is how good the car is feeling, so today so far has been a very positive day for us.”
The map is a revised version of one which was used prior to the Sydney test, and is said to have improved driveability for the Mustangs.
Herrod outlined the changes as, “A little bit of throttle feel, a little bit of idle hanging on, forward feed to the idle control and so forth; that's sort of it.
“It's more the driveability side of things that we've worked on a lot.”
The process entails Herrod Performance Engines developing the map, which is verified by Ford and then approved by Supercars, the latter of which is responsible for loading the map into each car (consistent with the random engine allocation which ensures fairness within each make).
Herrod, who is joined at Winton by his chief technician, Bobby Ervin, expects that today's map is that which will be ticked off by Supercars for use this season.
“We believe it's right now; we're 99.99 percent sure,” he declared.
“Bobby's worked on and finessed that calibration over the last week and then we've come here to make sure that everything's right. We're here to verify.
“We know everything on our dyno behind the scenes has worked very, very well, but you've got to get here, make sure, and as you probably heard, the cars are just running faultlessly.”