What size tyres are on the 20's? Have you changed the rolling radius over stock?

 

PTV is part of Porsche's response to criticism of the 997.1 cars being too biased towards understeer. Porsche "torque vectoring" controls where power gets laid down and gives the car more of a rear-wheel drive tail happy attitude. Anything I suggested is a longshot, but you have a very weird problem.

You really need to own the diagnosis yourself and figure out what's wrong with it, I've been through a relatively painful sequence myself with my 997.1 and at the end of the day the only person who really cares is you.

I highly recommend that you do some heavy braking tests - at least you can figure out if it is power application, or braking (chassis) that is the problem. My guess from your description is that there are some shenanigans going in the diffs or electronic control thereof.

 

I will say this. Porsches are VERY sensitive to tires. Also PNCA and their Reps are in My Experience VERY good and awesome people. Go back to stock and see what happens.

I would ask them about wheel speed. You might have one wheel going faster than another which will cause this. If its an 11 or newer they can see that.

 

I agree with 90sundevil thinking it is the tires. When I had my M6 I out different tires on the rear and the mismatch made it handle the same way. When I put 4 new tires on using the same brand and model it was fine.

 

My car wants to turn with throttle input. I tried to researched the yaw and steering wheel sensors yesterday. There isn't any detailed information I could find.

I agree with your analysis that is related to electronic sensors giving wrong data and causing the diff to do the wrong thing.

I had the location of all the sensors I could check if they are at least connected correctly or if the wires were damaged.

 

After reading the 991 lemon thread I'm gonna call say hell NO to that one as a rule.