United Kingdom, Ireland Region  Discussion for members in the UK & Ireland, local events, etc. |
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06-22-2009, 02:37 PM
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Porsche Prophet
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Join Date: Dec 2008
Location: Herts
Posts: 55
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Loss of power under acceleration
Hi,
I've just encountered a strange issue with my car, the power drops away whilst under heavy acceleration at various points between 4000-6500 rpm 
It's fitted with the following, possibly relevant modications, in case this throws any ideas:
a) Softronic plenum + V4.1 software
b) Milltek headers/cat-back exhaust
I've run the durametrics tool and no error conditions are reported on the DME. It feels a bit like a rev-limiter kicking in when the problem happens but after a bit of hesitation the car continues on again.
So far, I've taken apart the intake pipes and cleaned up a lot of oil near the MAF and associated ducts. Checked the exhaust for any signs of failure (Karel/Tess Tickle know why)... but no major improvement.
Any thoughts or ideas on what best to try next? I've read a huge number of messages on here to see if I can find any obvious fix but so far, other than cleaning MAF, there is nothing that stands out.
Regards
Steven
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06-22-2009, 02:52 PM
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PCA Cayman Register Advocate
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Join Date: Oct 2006
Location: Connecticut
Posts: 6,975
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Re: Loss of power under acceleration
Is there a blinking yellow light in your cluster during this loss of power? Sounds like you're experiencing wheel spin, which envokes the PSM Gods who ultimately pull the power back.
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PSM - Porsche Stability Management
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While it can’t overcome the laws of physics, the revolutionary Porsche Stability Management (PSM) system does lend an added degree of balance and control to the Cayman’s mid-engine driving dynamics, inspiring surefooted confidence in corners and extreme situations.
A standard feature on the Cayman and Cayman S, PSM continuously monitors steering input, road speed, yaw velocity and lateral acceleration to calculate the actual direction of travel. If the car begins to steer off line, PSM instantly intervenes with precision brake inputs on individual wheels to help bring the car back onto the driver’s intended path.
If braking alone isn’t enough to correct the vehicle’s cornering line, PSM then calls on the Cayman’s engine management system, adjusting engine output as needed to help stabilize handling. PSM can also compensate in an instant for mid-corner changes in load resulting from deceleration or braking. When Sport mode is selected with the optional Sport Chrono Package, PSM’s threshold for intervention is raised, allowing for greater driver involvement. If you prefer driving without automatic PSM assistance, the system can be set to standby at any time. In this case, it will only intervene under heavy braking, where both front wheels exceed the ABS threshold.
For all of its technical ability, PSM goes virtually unnoticed in everyday driving situations, preserving the Cayman’s natural agility. |
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__________________
Gator Bite
PCA Cayman Register Advocate
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06-22-2009, 03:47 PM
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Porsche Prophet
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Join Date: Dec 2008
Location: Herts
Posts: 55
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Re: Loss of power under acceleration
Originally Posted by Gator Bite
Is there a blinking yellow light in your cluster during this loss of power? Sounds like you're experiencing wheel spin, which envokes the PSM Gods who ultimately pull the power back.
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Sadly not, no PSM activation warning light and I double-checked with the PSM button switched off. Having just taken the car for another spin what happens is around 4800-5200 rpm it holds back - just like its starved of air/fuel or something it wants. Pushing the pedal just gets the car feeling like its pushing against something.. Then without warning it blasts off at full pelt straight up to the red line with a lot of force (more than I've felt before from the Cayman).
The only odd things are:
1. The breather pipe from the VOS to the Softronic plenum has become very very sticky and when the throttle is open (whilst stationary) the pipe seems to collapse until the throttle is released. I guess this has been like it for some time but it looks like it needs replacing.
2. I had a problem with the catback section of the exhaust the other week and as a temporary measure it was re-welded (new replacement en-route but probably 1-2 weeks away). Although the car has been driving fine for the past week with the welding in place.
Any more thoughts on the back of a postcard??
Cheers
Steven
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PSM - Porsche Stability Management
|
|
While it can’t overcome the laws of physics, the revolutionary Porsche Stability Management (PSM) system does lend an added degree of balance and control to the Cayman’s mid-engine driving dynamics, inspiring surefooted confidence in corners and extreme situations.
A standard feature on the Cayman and Cayman S, PSM continuously monitors steering input, road speed, yaw velocity and lateral acceleration to calculate the actual direction of travel. If the car begins to steer off line, PSM instantly intervenes with precision brake inputs on individual wheels to help bring the car back onto the driver’s intended path.
If braking alone isn’t enough to correct the vehicle’s cornering line, PSM then calls on the Cayman’s engine management system, adjusting engine output as needed to help stabilize handling. PSM can also compensate in an instant for mid-corner changes in load resulting from deceleration or braking. When Sport mode is selected with the optional Sport Chrono Package, PSM’s threshold for intervention is raised, allowing for greater driver involvement. If you prefer driving without automatic PSM assistance, the system can be set to standby at any time. In this case, it will only intervene under heavy braking, where both front wheels exceed the ABS threshold.
For all of its technical ability, PSM goes virtually unnoticed in everyday driving situations, preserving the Cayman’s natural agility. |
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06-22-2009, 04:05 PM
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Platinum Sponsor
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Join Date: Jan 2008
Location: CT
Posts: 589
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Re: Loss of power under acceleration
Hello,
The VOS would have nothing to do with this as you describe.
What was the prob with the cats as they can cause this . The MAF is another problem that causes these types of issues..
Best,
Scott
Originally Posted by i3qsystems
Sadly not, no PSM activation warning light and I double-checked with the PSM button switched off. Having just taken the car for another spin what happens is around 4800-5200 rpm it holds back - just like its starved of air/fuel or something it wants. Pushing the pedal just gets the car feeling like its pushing against something.. Then without warning it blasts off at full pelt straight up to the red line with a lot of force (more than I've felt before from the Cayman).
The only odd things are:
1. The breather pipe from the VOS to the Softronic plenum has become very very sticky and when the throttle is open (whilst stationary) the pipe seems to collapse until the throttle is released. I guess this has been like it for some time but it looks like it needs replacing.
2. I had a problem with the catback section of the exhaust the other week and as a temporary measure it was re-welded (new replacement en-route but probably 1-2 weeks away). Although the car has been driving fine for the past week with the welding in place.
Any more thoughts on the back of a postcard??
Cheers
Steven |
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|
|
|
|
PSM - Porsche Stability Management
|
|
While it can’t overcome the laws of physics, the revolutionary Porsche Stability Management (PSM) system does lend an added degree of balance and control to the Cayman’s mid-engine driving dynamics, inspiring surefooted confidence in corners and extreme situations.
A standard feature on the Cayman and Cayman S, PSM continuously monitors steering input, road speed, yaw velocity and lateral acceleration to calculate the actual direction of travel. If the car begins to steer off line, PSM instantly intervenes with precision brake inputs on individual wheels to help bring the car back onto the driver’s intended path.
If braking alone isn’t enough to correct the vehicle’s cornering line, PSM then calls on the Cayman’s engine management system, adjusting engine output as needed to help stabilize handling. PSM can also compensate in an instant for mid-corner changes in load resulting from deceleration or braking. When Sport mode is selected with the optional Sport Chrono Package, PSM’s threshold for intervention is raised, allowing for greater driver involvement. If you prefer driving without automatic PSM assistance, the system can be set to standby at any time. In this case, it will only intervene under heavy braking, where both front wheels exceed the ABS threshold.
For all of its technical ability, PSM goes virtually unnoticed in everyday driving situations, preserving the Cayman’s natural agility. |
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Last edited by Softronic; 06-22-2009 at 04:07 PM.
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06-22-2009, 04:12 PM
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Porsche Prophet
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Join Date: Dec 2008
Location: Herts
Posts: 55
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Re: Loss of power under acceleration
Originally Posted by Softronic
Hello,
The VOS would have nothing to do with this as you describe.
What was the prob with the cats as they can cause this . The MAF is another problem that causes these types of issues..
Best,
Scott
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Thanks Scott - I was wondering about potential cat failure as a friend had a similar performance issue when he swapped his exhaust around the same RPM band.
Is the breather hose "sucking in" under throttle normal between the VOS and the plenum? The outside was sticky and coated my fingers in a black sticky substance (not oil) just touching it.
Time to think about calling Milltek again in the morning 
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06-22-2009, 04:43 PM
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Porsche Activist
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Join Date: Aug 2007
Location: MD
Posts: 354
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Re: Loss of power under acceleration
Try cleaning your MAF sensor with some MAF solvent, sounds like its oily which is a problem I have to deal with every 2000 miles or so since I put on the SRP. Good Luck!
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06-22-2009, 05:43 PM
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Platinum Sponsor
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Join Date: Jan 2008
Location: CT
Posts: 589
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Re: Loss of power under acceleration
Originally Posted by i3qsystems
Thanks Scott - I was wondering about potential cat failure as a friend had a similar performance issue when he swapped his exhaust around the same RPM band.
Is the breather hose "sucking in" under throttle normal between the VOS and the plenum? The outside was sticky and coated my fingers in a black sticky substance (not oil) just touching it.
Time to think about calling Milltek again in the morning |
Yes the hose can suck in when there is not more positive pressure from the crankcase and is normal. In fact they have all done this since day one.
I would suspect the cats and or as Intubator stated the MAF although the cleaning every 2k seems to be more than any others..
Best,
Scott
Last edited by Softronic; 06-22-2009 at 05:46 PM.
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06-24-2009, 08:02 AM
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Porsche Prophet
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Join Date: Dec 2008
Location: Herts
Posts: 55
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Re: Loss of power under acceleration
Thanks for the advice - I cleaned the MAF with a solvent cleaner as suggested on here and the local garage. It made a marginal improvement but nowhere near perfect.
Therefore visited the local OPC and bought a new MAF. Once fitted the cars performance is totally transformed
Thanks to everyone for the help I received.
Regards
Steven
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06-24-2009, 09:17 AM
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Porsche Chatter
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Join Date: Dec 2008
Posts: 34
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Re: Loss of power under acceleration
Hi mate,
what did you pay for the MAF sensor? and did you change it yourself?
Cheers
shan
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06-24-2009, 01:52 PM
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Porsche Prophet
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Join Date: Dec 2008
Location: Herts
Posts: 55
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Re: Loss of power under acceleration
Originally Posted by Shanny993
Hi mate,
what did you pay for the MAF sensor? and did you change it yourself?
Cheers
shan
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I paid... wait for it.. a whole £300 quid for the thing. Fitting it took me 15 minutes and the result was instant. I'd rung a lot of others on the Internet but decided against their options of fixing mine (around £100) or buying a secondhand one at £150-200. Someone else could get a new one in 2-4 days but I needed my car tomorrow and Monday.
The good bit, having spent that much money, is the car is driving really well now. Better than ever and I suspect the MAF wasn't great all along.
Regards
Steven
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