Hello all!
I need some help with an intermittent issue.
03 996 C4S
Coming down and into a turn, occasionally I hear and feel a quick clicking/vibration and almost feel like I loose control for a second.
I feel like it’s a PSM or ABS issue. And it can happen at normal speeds
like a downhill circular on-ramp.
Going up hill no issues. Did notice a light come on during the brief events. It was on the left side. Perhaps the warning light.
No codes come up.

 

Fairly vauge on info here but a guess would be a bad wheel speed sensor. U need to figure out what warning light is turning on. Also a good scanner can log the speed sensor values and u will see an intermitant issue in the gragh.

Since u have a c4 it can also be any of the mechanical items in the front like diff, axle shaft or even a wheel bearing

 

Thank you for the response!
A friend of mine called and said that he also felt the same “ABS like” sensation going around a downhill turn after he replaced only the rear tires. When he replaced all 4 tires with new, the issue went away! I’m guessing that the sensors, PSM?, are sensing different speeds from the rear and fronts and making micro adjustments. Fronts and rears are the same make and size, but the rears are 2 years newer.

 

All very posible. C4s r very sensitive to tire size. What r your current tire sizes?

 

I just replaced only the rear tires on my 03 4s (295/30ZR-18 MICHELIN PILOT SPORT 4S XL) and had a similar floaty front feeling when taking a curve at high speed. Plan on just ordering new fronts even though they have plenty of tread left.

 

If the steering angle sensor is not correctly calibrated it can cause this too. Need someone with a PIWIS to check/calibrate the steering angle sensor; durametric claims to do it but does not actually work.

 

New Rears are 295/30 zr
2 yr old Fronts are 225/40 zr

 

Those appear to be correct for a c4 so maybe its just something with the traction control

 

I’ll return to this thread after I’ve changed out all 4 tires and see if that makes a difference. If that doesn’t help, then I’ll start digging deeper and looking at the traction control, etc. Thanks for your help!
Jens Mueller

 

Does this vibration happen while braking?