Not Smooth when coming off the throttle

[Caymanwhite]

Porsche Cayman S 2009 Gen II 47k miles. Fully Porsche serviced. Major just completed.
The issue I have has been with the car throughout my (to date) 1 year ownership.
Car performs well all-round. I am referring only to road driving (not track)

I was hoping a Porsche Technician could provide a solution to the following. They acknowledge what I am finding , but have no solution at this time.

Using any gear, when the engine Revs are 3000 or less, or reducing down from 3000 RPM and slowing the car down by coming off the gas / throttle regardless of how "smooth / slow" I come off throttle/gas the whole car gives the feeling that the engine wants to shut down.
The Rev range does not drop any quicker (looking at the disk. All seems normal) it's just the car "jerks" or feels it wants a sudden" shut down. I.e. I loose any smoothness when slowing down. This is compared to other cars (including Porsches) that I drive.

It's more prominent or more noticible in slow moving (traffic) situations and less so, but sill there on open roads when coming off the gas at 3000 RPM or less.

Has a recent Major sevice, new plugs etc.etc.

Any ideas from the Pistonheads community?

[AW10]

I'd be wondering if the Throttle Position Sensor was faulty?

[Caymanwhite]

Thanks AW10
This is exactly what I need.
Something to go back to the OPC with to suggest they look in a particular direction.

(Is what you refer to like / similar to a potentiometer?, I had such on an Audi went on me after water got in)
Many thanks

[AW10]

I did a bit of digging; apparently a faulty brake lamp switch can cause issues as well - if the traction control thinks you're braking and applying the throttle at the same time it can react unpredictably. Do the symptoms change when the traction control is turned off?

Edited by AW10 on Tuesday 20th June 22:14

[Rockster]

Caymanwhite said:

Thanks AW10
This is exactly what I need.
Something to go back to the OPC with to suggest they look in a particular direction.

(Is what you refer to like / similar to a potentiometer?, I had such on an Audi went on me after water got in)
Many thanks

If you are using an OPC that requires you supply it with suggestions as to what is wrong you are using the wrong OPC.

You should only need to supply the conditions under which you observed the behavior so the tech can reproduce the behavior if he needs to. My WAG is he will be familiar enough with the car to know what's going on.

[anonymous-user]

AW10 said:

I did a bit of digging; apparently a faulty brake lamp switch can cause issues as well - if the traction control thinks you're breaking and applying the throttle at the same time it can react unpredictably. Do the symptoms change when the traction control is turned off?

If that was the problem I reckon it should be easy to spot because the brake lamps would be illuminated all the time.

I'm wondering whether what OPs describing is the complete fuel shut-off which occurs in modern cars if you take your foot right off the gas when the car's moving. If you're driving at, say, 20 mph in second gear on a flat road try taking your foot completely off the accelerator and then do nothing - the car will get slower and slower but it won't slow to a stall - eventually you'll feel the engine pick up as the fuel injection cuts back in and you'll continue pottering along at tickover.