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#17
04-13-2007, 08:43 AM
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Re: Diagnostic Code
Sorry, I was thinking of another type of variable cam system. The VVT system modifies the cam timing, not the cam lobes used.
http://www.billzilla.org/vvtvtec.htm The concept of lower oil pressure preventing a higher-performance cam configuration still holds.
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Forum Guidelines:http://www.automotiveforums.com/vbulletin/guidelines.html "What we've got here is a failure to communicate" Last edited by Brian R.; 04-13-2007 at 10:43 AM. 
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#18
04-14-2007, 06:14 AM
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Re: Diagnostic Code
I now understand how the oil pressure affects the cam timing. Is this system how higher performance is attained or just a way to protect the engine at higher speeds?
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#19
04-14-2007, 01:05 PM
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Re: Diagnostic Code
Advanced cam timing shifts the torque curve upward to higher rpms, which makes the engine more powerful at higher rpms. The cost of this is less drivability and torque at lower rpms. A test for correct operation of the VVT system is to activate it at idle. The engine should idle rough or die because the high-rpm cam timing is not suitable for low-rpm use.
Conversely, a cam timing/lobe profile that is good for mileage and low-rpm torque is not optimum for high-rpm performance - the engine doesn't breath as well. With the VVT system, you have a good low-rpm cam profile/timing. The system is changed at some rpm (4000 or so) to give a more aggressive cam timing, increasing the high-rpm torque/performance. When low oil pressure prevents the cam timing from changing as it's supposed to, it is not adequate to protect the engine. The only way to really protect the engine is to shut it down. Keeping the engine from creating maximum hp at low oil pressure is just a by-product of the VVT system.
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Forum Guidelines:http://www.automotiveforums.com/vbulletin/guidelines.html "What we've got here is a failure to communicate" Last edited by Brian R.; 04-14-2007 at 04:39 PM.
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#21
04-14-2007, 04:30 PM
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Re: Diagnostic Code
Just lie to the computer - See the 3rd page of the description in the TSB above
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Forum Guidelines:http://www.automotiveforums.com/vbulletin/guidelines.html "What we've got here is a failure to communicate"
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#23
04-14-2007, 10:54 PM
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Re: Diagnostic Code
I don't know. It might be a CAN function that is enabled in the more modern diagnostic instruments...
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Forum Guidelines:http://www.automotiveforums.com/vbulletin/guidelines.html "What we've got here is a failure to communicate"
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