Paul Tracy rued his car's lack of balance around the Portland track, after qualifying 10th for the second consecutive race.
The Canadian said: "Me and Eric [Zeto, his race engineer] just aren't on the same page in terms of set-up at the moment.
"We've been struggling all year with understeer and even here, where the reds [soft compound tyres] seem to be working better than they have at previous races, we've still got a major issue wiith understeer whether we're on the reds or blacks [hard compound]."
Despite not expecting to seek similar handling traits as his new teammate AJ Allmendinger, Tracy is currently using the same set-up as the youngster.
"Yeah, other than weight distribution - because he's a fair bit lighter than me - our set-ups are pretty close, and yet he's having much fewer understeer problems than us.
"Looking at the data, he can roll into the corner quicker than I can, and pick up the throttle earlier.
"For me, the problem is, I'm having to over-slow the car into the braking area, I'm still getting understeer mid-corner, and then I can't get back on the throttle soon enough. Turns 4, 7 and 12, we're just getting killed."
Tracy is going to work with his team now on alternate fuel strategies, which Cristiano da Matta proved last year can work at Portland.
Driving for PKV Racing, the Brazilian dropped to 13th at Turn 1 on the first lap, but pitted early and with a yellow flag period, fought through to beat Sebastien Bourdais and Tracy.
A deeply frustrated PT said: "Yeah, we're going to go out of sequence, and try and salvage what we can. To be honest, that's all we can do.
"This is absolutely what we didn't need after how our year's been so far."