Hiccup at 3500 RPM ?
04-09-2008, 08:59 AM
#1
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Thread Starter
Hiccup at 3500 RPM ?
Hi
I have a 06 C2 that runs well, but i have noticed that often, when accellerating, between 3500 -4000 rpm that the engine/transmission seems to slip for a second
I searched, but could not find - apologize if this has been mentioned
Any insight welcome
I have a 06 C2 that runs well, but i have noticed that often, when accellerating, between 3500 -4000 rpm that the engine/transmission seems to slip for a second
I searched, but could not find - apologize if this has been mentioned
Any insight welcome
04-09-2008, 10:24 AM
#3
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Variable Cam is kicking in. Happpens at around 3200 RPM on my 02 Carrera
Here's the write up from Porsche AG for the 997:
VarioCam Plus is a remarkably innovative system that continually adjusts the valve timing for optimum performance at all times. Key benefits include increased power and torque at all engine speeds as well as smoother running, better fuel economy and fewer exhaust emissions.
VarioCam Plus combines variable valve timing with two-stage lift on the intake side. The two-stage valve lift function is performed by electro-hydraulically operated switchable tappets. Each of these 12 tappets consists of concentric lifters, which can be locked together by means of a pin. The inner lifter is actuated by a small cam lobe, while the outer ring element is moved by a pair of larger-profile lobes. The timing of each valve is seamlessly adjusted by means of an electro-hydraulically operated rotary vane adjuster located at the head of each intake camshaft.
The valve timing and valve profile are continuously changed according to conditions and engine load. For example, for cold starting and initial responsiveness, VarioCam Plus raises the amount of lift and retards the valve timing. At medium revs and minimal load, the valve lift is lowered and timing advanced to help minimize fuel consumption and emissions. While for maximum power and torque, the lift is raised and the timing advanced.
All operations are controlled by a powerful ECU that manages the engine's operation and makes the appropriate adjustments. On-board diagnostics provide continuous monitoring and early fault detection for the exhaust and fuel supply systems. This results in active prevention of harmful emissions as well as consistent fuel consumption.
Here's the write up from Porsche AG for the 997:
VarioCam Plus is a remarkably innovative system that continually adjusts the valve timing for optimum performance at all times. Key benefits include increased power and torque at all engine speeds as well as smoother running, better fuel economy and fewer exhaust emissions.
VarioCam Plus combines variable valve timing with two-stage lift on the intake side. The two-stage valve lift function is performed by electro-hydraulically operated switchable tappets. Each of these 12 tappets consists of concentric lifters, which can be locked together by means of a pin. The inner lifter is actuated by a small cam lobe, while the outer ring element is moved by a pair of larger-profile lobes. The timing of each valve is seamlessly adjusted by means of an electro-hydraulically operated rotary vane adjuster located at the head of each intake camshaft.
The valve timing and valve profile are continuously changed according to conditions and engine load. For example, for cold starting and initial responsiveness, VarioCam Plus raises the amount of lift and retards the valve timing. At medium revs and minimal load, the valve lift is lowered and timing advanced to help minimize fuel consumption and emissions. While for maximum power and torque, the lift is raised and the timing advanced.
All operations are controlled by a powerful ECU that manages the engine's operation and makes the appropriate adjustments. On-board diagnostics provide continuous monitoring and early fault detection for the exhaust and fuel supply systems. This results in active prevention of harmful emissions as well as consistent fuel consumption.
