PIS setting 360?

PIS does not change with clutch wear - it is a fixed* distance (in mm) from the Auto Calibrated Closed Clutch Position (which does change with wear).

What was the clutch degradation index? That'll give you an insight into the condition of the clutch.

*When I say fixed, it can be changed using a diagnostic tool.

 

My '04 has a PIS of 4.8mm two months ago at 19K miles. Estimated wear was 36%. The car shifts perfectly in my opinion. Perhaps a bit stately in "normal" but perfection in "sport". I wouldn't change a thing at this point.

Cheers, Andy

 

Just because a PIS value in one car shifts well it doesn't mean the same value in a different car will work the same. Each car should have their system set up according to the condition of the clutch/flywheel. Also, the parameters should be checked and adjusted (if needed) regularly.

 

Aldous
Which parameters should be checked and adjusted regularly? If the PIS doesn't change what does?
Thanks
Alan

 

When I purchased my car, the engagement was terrible when starting in first gear. Had the PIS adjusted as the computer stated I had 90% clutch life. After several trips and having the PIS adjusted to try to fix the problem, the mechanic used the computer to do some measurements. When he was done, he told me that the measurements did not add up and based on his calculations and the measurements for the clutch to actually engage, there was only 30% clutch left remaining. When he reset all the parameters the car's take off from first gear was much better.

Of course the car was back in the shop in four months to have a new clutch put in.

 

Your understanding is incorrect. Point of initial slippage is how far the pressure plate needs to be compressed before the clutch slips. The computer compensates as the clutch wears but not perfectly. It is not unusual for small adjustments to keep best operation over the life of the clutch. The computer just does not do a great job compensating for the changing geometry and that is why failures start happening in the 70% wear area when a stick shift car can continue to work well with the same wear.

 

PIS should be checked and adjusted if needed (as Brian re-iterates above). The Clutch Degradation Index should also be monitored - it give you an idea of how well the clutch is operating.

Other useful parameters keeping an eye on include opposite gear engagement errors (possible actuator failure), Solenoid Valve Leakage values, Clutch Over PIS errors (possible sticky release bearing), etc, etc.

Having a nose around the ECU's before a service can give valuable information to a technician and, in my opinion, is an essential part of the service.

Re: your second question....

The PIS doesn't change as it is a reference point from the Self Calibrated Closed Clutch Position (CCP). This is a parameter which tells the TCU the position of the release bearing when the clutch is fully closed. As the name suggests, it is calibrated after each gearshift.

As the friction material wears down, the CCP changes. However, the PIS parameter doesn't as it is a point referenced from the CCP.

 

A really good mechanic that knows how to use the computer and understands the parameters can do some calculations (these are different from the PIS - sorry as I cannot remember what they were called). Based on the calculations, they can reset some parameters THEN the PIS to help the shifting. This will also give you a more accurate reading on the remaining clutch life (at least it did with me).