03 C4S clutch pedal problems + other minor problem.
08-28-2013, 03:33 PM
#16
Burning Brakes
Thread Starter
Ok I found the post. Here it is from a use named Gator Bite
"It's not really a "Clutch Delay Switch". A "Clutch Delay" would slow the release of the clutch, and it's usually a mechanical device like a manifold with a fixed orifice to slow the flow of hyrdaulic fluid from the cluch slave cylinder. BMWs (expect M models) use a clutch delay to make the cars easier to drive / harder to stall.
The switch you're talking about does one thing for several reason, one of them overlaping the benefits of a clutch delay. It retards the timing when you press the clutch, and for a short time after the clutch has been released.
1. Retarding the timing reduces shift jerk which makes shifts smoother, but more importantly protects the Dual Mass Flywheel from damage.
2. During take offs, retarding the timing reduces the chances of knock/ping on clutch release. This makes it much easier to launch without stalling (the overlap I was taking about).
3. By knowing when the clutch is being depressed, the DME can widen the range of acceptability in it's misfire detection module.
Here's a quote directly from the Porsche Tech archives: "The program that evaluates misfire is complex. it has to be able to distinguish between deceleration caused by rough roads, potholes, shifting, and other non misfire causes, and deceleration caused by misfire."
4. By knowing then the car is shifted (watching the clutch), the Torque Control can reduce engine braking during high torque downshifts.
Here's another quote from the archives: "On deceleration with unacceptably high engine braking when downshifting, engine drag torque control (MSR) prevents the drive wheels from locking on a slippery road by slightly opening the throttle valve."
So by removing that switch, you may in fact feel some added sharpness to throttle response when shifting. Because now you have a sharper timing curve. But you will be castrating all 4 of the benefits mentioned above. To summarize:
1. You may experience premature failure of your DMF
2. You may find yourself stalling your car more frequently, and you may find that your car has less power than before, because when it preignites - the DME is going to pull the timing back and keep it back for a while.
3. You may experience a Check Engine Light, and investigation may reveal random misfire codes.
4. You may notice locking of the rear wheels after high RPM downshifts. This is most likely to be noticed on slippery surfaces like rain or snow, and it is likely to cause oversteer."
I bolded the main points. If this is true, this switch does affect other things. Thus, explaining why my car is driving differently.....
"It's not really a "Clutch Delay Switch". A "Clutch Delay" would slow the release of the clutch, and it's usually a mechanical device like a manifold with a fixed orifice to slow the flow of hyrdaulic fluid from the cluch slave cylinder. BMWs (expect M models) use a clutch delay to make the cars easier to drive / harder to stall.
The switch you're talking about does one thing for several reason, one of them overlaping the benefits of a clutch delay. It retards the timing when you press the clutch, and for a short time after the clutch has been released.
1. Retarding the timing reduces shift jerk which makes shifts smoother, but more importantly protects the Dual Mass Flywheel from damage.
2. During take offs, retarding the timing reduces the chances of knock/ping on clutch release. This makes it much easier to launch without stalling (the overlap I was taking about).
3. By knowing when the clutch is being depressed, the DME can widen the range of acceptability in it's misfire detection module.
Here's a quote directly from the Porsche Tech archives: "The program that evaluates misfire is complex. it has to be able to distinguish between deceleration caused by rough roads, potholes, shifting, and other non misfire causes, and deceleration caused by misfire."
4. By knowing then the car is shifted (watching the clutch), the Torque Control can reduce engine braking during high torque downshifts.
Here's another quote from the archives: "On deceleration with unacceptably high engine braking when downshifting, engine drag torque control (MSR) prevents the drive wheels from locking on a slippery road by slightly opening the throttle valve."
So by removing that switch, you may in fact feel some added sharpness to throttle response when shifting. Because now you have a sharper timing curve. But you will be castrating all 4 of the benefits mentioned above. To summarize:
1. You may experience premature failure of your DMF
2. You may find yourself stalling your car more frequently, and you may find that your car has less power than before, because when it preignites - the DME is going to pull the timing back and keep it back for a while.
3. You may experience a Check Engine Light, and investigation may reveal random misfire codes.
4. You may notice locking of the rear wheels after high RPM downshifts. This is most likely to be noticed on slippery surfaces like rain or snow, and it is likely to cause oversteer."
I bolded the main points. If this is true, this switch does affect other things. Thus, explaining why my car is driving differently.....
08-28-2013, 05:21 PM
#17
Very interesting. When mine was failing the only thing it affected was engaging the starter, once started there was no difference in the operability of the car. I even had a Porsche tech suggest that I could bypass the switch but the risk would be engaging the starter with the car in gear.
Keep hunting, will be great to know what the solution is.
Keep hunting, will be great to know what the solution is.
08-29-2013, 12:38 PM
#18
Burning Brakes
Thread Starter
I noticed my spring in fact is broken and it was always broken since I bought the car a few years ago. So I got used to the "heavy" clutch feel. I'll replace the spring and see if I like it or not.
The reason for the noise and weird crunch feeling was the spring itself, the broken pieces dislodged and started interfering.
I'm taking the car to the shop next week to change my rear tires and they'll try to figure it out. if they can't, I'll change the clutch interlock switch and if that doesn't change anything, I’ll have to have diagnostics done to see what changed the engine characteristics...
The reason for the noise and weird crunch feeling was the spring itself, the broken pieces dislodged and started interfering.
I'm taking the car to the shop next week to change my rear tires and they'll try to figure it out. if they can't, I'll change the clutch interlock switch and if that doesn't change anything, I’ll have to have diagnostics done to see what changed the engine characteristics...
