Edgy01

I wondered how many of you have your steering angle sensor calibrated after having your suspension alignment changed. I was reading recently through my workshop manual and feel that step may be getting bypassed by some shops not familiar with these cars. It's all critical to the proper functioning of the PSM.


The steering angle sensor of the 911 Carrera must be initialised or calibrated after the work below has been carried out.
Initialising - following each interruption of the Terminal 30 power supply
Calibrating - following any work on the vehicle (e.g. suspension alignment, change of parts)

The steering angle sensor (arrow) consists of an optical segment sender and a code disk, which are integrated in the steering column switch. The light emitted by the segment sender is interrupted by the inner ring in a specific sequence resulting in 5 segments with 72° per revolution. The outer ring is set up to cause interruptions of varying length from which the system can calculate the exact steering angle. The data measured in the integrated micro processor is sent to the PSM control unit via the CAN bus.
The PSM control unit thus receives the information on the lock angle of the front wheels (driver intention with regard to direction of travel). This signal is used inside the PSM control device to determine the optimum vehicle behaviour with regard to its longitudinal dynamics through offsetting the speed of travel.

mdrums

Edgy, excellent point! I even forget to mention this in my posts when I try to help with track alignment advise.

I just got my 2nd alignment for the year 3 weeks ago and my steering angle was off. We dialed in thhe alignment which gets off due to track use and the steering sensore was off too.

Excellent reminder here!

ADias

How's that re-calibration done?

cbzzoom

I wonder if this could be intentionally adjusted wrong to make PSM kick in a little less.

cello

Edgy - Thanks and interesting. Did not know of the affirmative re-calibration..

Mike - Your race shop re-calibrates as part of its alignment? Anything more to it?

Will be doing GT3 CA/susp upgrades and a track alignment via our race shop on my new car so have a vested interest .. TIA!

mdrums

PWISI tool. I watched my shop do it and it take sometime...after the alignment they hook up the car to the computer and call up the Steering Angle screen and you get the wheel as straight as possible...it is very sensative....1 micro touch sends the reading off. Once you get it just right it basically shows zero degrees and you save it.

Edgy01

The complexity of these cars continue to amaze me. I try to learn more about these things weekly and still I know so little. It's good to know that some techs know that this stuff is important.

ADias

And we need to be on top of things to monitor what service depts do. Thanks Dan!

mdrums

Exactly....I have lost a lot of faith in Porsche dealer mechanics. They just do not seem to be into the details like some of the independant shops are. Lucky for me my indy shop in Tampa is good, they have certified Porsche mechanics and a PWISI tool.

cello

Thank you!

You are not kidding .... Thx for the info!

rijowysock

interesting, ill have to ask Vortex to check this next time i get alignment... due for one soon i think.

mdrums

Riley get Carlos at Vortex to do your alignment and check the steering angle. They normally also do this anyway...at least on my car for my track alignments.

REBor8

Great info, Dan. Thanks.