Ford's Mostert behind 8-ball in Townsville

After a Friday to forget, Supercars star Chaz Mostert says he's heading into this weekend's Townsville 400 behind his rivals.

The Tickford Racing driver only ran five laps in a wet morning practice session before a mystery engine drama undermined his run in the day's second session.

It meant Mostert could only complete 10 laps in the half-hour session in the afternoon and finished 14th on the timesheets.

The Ford ace heads into the Townsville round 546 points off championship leader Scott McLaughlin and fourth on the standings.

He's also dealing with speculation over his future, with a deal beyond this year's championship at either Tickford or another team yet to be announced.

While he's confident his team has got on top of the issues that plagued his Mustang on Friday, he admits he's got ground to make up.

"Whatever we changed seemed to fix it, just the engine wasn't quite running right. Bit of a pain in the bum for our Friday running," Mostert told AAP.

"No doubt we're behind the eight-ball now for the weekend.

"Lot of work to do."

The Townsville 400 resumes on Saturday with a third and final practice session before a 20-minute qualifying session to determine the grid for a 200km race starting at 3.10pm.