Knock sensor and adaptive timing

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08-12-2008, 07:26 PM

BruceH

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Knock sensor and adaptive timing

Learn on your own, I'm done.

Last edited by BruceH; 11-13-2010 at 10:08 AM.

08-12-2008, 08:23 PM

GT John

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Quote:

Originally Posted by BruceH

Can someone help me to understand the limits of the factory knock sensors in relation to timing. As I understand it will retard the timing upon sensing detonation. Does it work the other way? As in will it advance the timing as long as knock isn't detected? What's the maximum spark advance with the factory tune?
The question I'm trying to ask is if I put a higher octane gas in the car will the timing advance because of lack of sensed knock thus giving an increase in HP? Or will my wishful thinking end up putting carbon deposits in the engine and wasting money?

Thanks,
Bruce

PS This question is in relation to a 2008 GT

To answer your first question........yes. Timing can be automatically increased until knock is detected. Once detected the timing will be retarded. This is generally is done in .5 second.

The maximum spark advance is determined on a dyno. Spark advance is increased until torque begins to drop then it is backed off 2 degrees. This is the maximum spark advance for your engine.

If you are planning on running a higher octane fuel in your engine you will need a canned or custome tune by one of the site sponsors. You can always have multiple octane tunes ie. 87, 91, 93 also you can go with a torque tune, performance tune or race tune.

I run the 93 Octane Race Tune in my daily driver and get 20mpg using Shell V Power. Its all in the tune.

Later

08-13-2008, 03:56 AM

jahudso2

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Knock sensors are not for fine tuneing of spark advance. Sometimes they tell the engine that knock occurs when there is no knock and sometimes it doesnt detect real knock. They can advance or retard the timing slightly, but most car companies just use the knock sensor as a kind of emergency warning that timing needs to be retarded. Like said before, you need a custom tune for different octanes to really benefit from different octane levels.