Hi all. Has anyone heard of PSM starting to go off for almost
no reason?

Today and recently in a gradual left-hand corner at typical
fast traffic speeds, my PSM kicks in, seeming to put the brakes
to the right front wheel. It drops the outside front as if my
spring had collapsed! In fact, part of my recent concern to do
corner weights was because that happened a couple of times
last week.

I talked to a Porsche mechanic informally about it, and he
suggested that I was either running tires of different diameters,
or interestingly, that the MAF unit was failing!

I just ran tape around both my front tires, and verified they were
the same...
???

 

Oh, and to follow up, if I turn off PSM the car drives and
handles just fine...

 

How about the difference diameters front and back?

 

is it chipped by any chance Joe?

 

no, but I was planning on looking into that...

 

I was going to look into a custom chip program, but not if
it is going to cause wierd problems...

 

Joe,

Have them hook it up to the computer. The code will tell you what's wrong.

I was getting the PSM/ABS light and thought it was b/c of my chip when in reality it was just a bad MAF sensor.

He also mentioned low brake fluid levels as well as unbalanced tire pressures would trigger the lights.

 

thanks a lot. I'll do that.

 

joe, have you done any suspension changes? double check your drop links make sure they are all connected to the correct holes.

 

Yes, I just had my alignment done.

 

Not just alignment but the actual specs of toe in, total toe, camber and straight ahead steer, then tire rolling diameters/pressure (may have been fine initially, but with some wear--especially asym. wear), then bad sensors. If your specs are close or just outside of range, a little change in the tires can trick PSM and if you turn off PSM, the car is just fine. The dealer should be able to figure it out.

 

Are the tires on each axle worn at the same rate? If you have replaced a flat on one corner, you now have tires running at different revs per mile. Have you varied tire sizes from OE? That could do it.