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porschephd · 03-21-2006, 07:28 PM

Knock sensors in the 5.2, 7.1, 7.2 and 7.8 cars is not for fuel economy. Your four 02 sensors are for that. They determine fuel economy as well as low throttle drivability.

Knock sensors are a very valuable tool to tune with. Why? Because they pick up a frequency that is just on the cuff of damage. To properly tune a car you watch these sensor and see what they are doing. Any knock count is a problem. Ideally you would steady state a car on the dyno and bring the timing up and watch the TQ. As the TQ nears it peak and the knock sensor counts at all you back off the timing and you have achieved max timing for that mark as well as max HP. Each cell (100RPM) is tuned in this fashion through the whole kPa map. Knock sensors are not a tool for anything other than protection. We use them in tuning and in fact will be installing them on all of our older CIS to EFI conversions.

We do not shut off any sensor. Not now not ever. If one has to tune in a fashion that causes the CEL to come on then he doesn't know what he is doing or has done something incorrect. A cars tuning is either safe and correct or it is not. Not running cats these days is a poor excuse for a light. The new style cats do not restrict flow and certainly retains drivability since the aft 02 actually control this map.

Tuning 7.2 is not easy...there are over 18 maps that switch based on a 3D overview of several components. Instead of just pulling timing it switches whole maps. The TT for example has 2700 maps in total. The original programming takes another piece of software to write just to fire up the motor. Man can not interpret all the maps and how they cross relate. It then takes 100K hours, yes that is correct to dyno the car.

Rarely will you find anyone who has GIAC and has issue. In fact in the last year we have removed over 70 other "tuners" ecu mods and placed ours in there. We have proudly tuned more cars and introduced things such as switching and flashloading that shows a learning curve and understanding of the programs second to no one.

Can gains be made without FI. Sure. What happens is Porsche writes the maps to deal with the worst of owners. People that would run 85 Octane if they could find it. What we do is go back in and look at all these maps. We then retune the system for 91 octane and level the maps not to deal with trying to run on 85 but nothing less than 91. So we are able to increase timing, offset and increase the VE table as well as the injector PW. The end result is a real world gain. The down side…you have to run 91 at minimum. Then again you should be doing this anyway..

My apologizes in advance if there are grammatical errors. It has been a long day and I am rather beat and headed off to bed!

03-21-2006, 07:28 PM	#18
porschephd Registered User Join Date: Jan 2006 Location: Kansas City Posts: 6	Knock sensors in the 5.2, 7.1, 7.2 and 7.8 cars is not for fuel economy. Your four 02 sensors are for that. They determine fuel economy as well as low throttle drivability. Knock sensors are a very valuable tool to tune with. Why? Because they pick up a frequency that is just on the cuff of damage. To properly tune a car you watch these sensor and see what they are doing. Any knock count is a problem. Ideally you would steady state a car on the dyno and bring the timing up and watch the TQ. As the TQ nears it peak and the knock sensor counts at all you back off the timing and you have achieved max timing for that mark as well as max HP. Each cell (100RPM) is tuned in this fashion through the whole kPa map. Knock sensors are not a tool for anything other than protection. We use them in tuning and in fact will be installing them on all of our older CIS to EFI conversions. We do not shut off any sensor. Not now not ever. If one has to tune in a fashion that causes the CEL to come on then he doesn't know what he is doing or has done something incorrect. A cars tuning is either safe and correct or it is not. Not running cats these days is a poor excuse for a light. The new style cats do not restrict flow and certainly retains drivability since the aft 02 actually control this map. Tuning 7.2 is not easy...there are over 18 maps that switch based on a 3D overview of several components. Instead of just pulling timing it switches whole maps. The TT for example has 2700 maps in total. The original programming takes another piece of software to write just to fire up the motor. Man can not interpret all the maps and how they cross relate. It then takes 100K hours, yes that is correct to dyno the car. Rarely will you find anyone who has GIAC and has issue. In fact in the last year we have removed over 70 other "tuners" ecu mods and placed ours in there. We have proudly tuned more cars and introduced things such as switching and flashloading that shows a learning curve and understanding of the programs second to no one. Can gains be made without FI. Sure. What happens is Porsche writes the maps to deal with the worst of owners. People that would run 85 Octane if they could find it. What we do is go back in and look at all these maps. We then retune the system for 91 octane and level the maps not to deal with trying to run on 85 but nothing less than 91. So we are able to increase timing, offset and increase the VE table as well as the injector PW. The end result is a real world gain. The down side…you have to run 91 at minimum. Then again you should be doing this anyway.. My apologizes in advance if there are grammatical errors. It has been a long day and I am rather beat and headed off to bed!