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Post by fairmont on Feb 3, 2009 11:58:00 GMT -5
If i turn down timing to 10 degree (to make sure there's no knock) and unplug the sensor will i see big difference in power or it will end up being just the same then more timing and sensor plug?
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Post by Stinger on Feb 3, 2009 13:44:34 GMT -5
That depends entirely on whether your knock sensor is currently retarding timing under load or not. If it is, it pulls a LOT of timing, more than is required. This is why they cost so much power in many cases. You could always give it a try. Just listen closely for a "rocks rattling in a can" sound from under the dash or around your feet. That is detonation and if you hear it, you'll need to get off the throttle and either pull more base timing, or plug the sensor back in.
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Post by svojohn on Feb 3, 2009 13:47:47 GMT -5
The knock sensor is not holding you back, it's protecting your engine from damage when the tune is bad. Leave the knock sensor alone and tune your engine for more power.
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Post by fairmont on Feb 3, 2009 14:58:48 GMT -5
Is the KS sensitive to anything else than pingging? You might think that i have stupid questions but believe me this spring i'm taking this 15 second Automatic car to mid 13 with the stock (very small) IHI.
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Post by svojohn on Feb 3, 2009 15:26:04 GMT -5
Is the KS sensitive to anything else than pingging? Quoted from a Ford document "KNOCK HARDWARE DESCRIPTION"; "NOISE, the threshold voltage, is a positive voltage in an RC circuit which is proportional to the Knock Input level at the time that a charging pulse, KTS, is output. This threshold voltage is established to avoid treating rod knock, piston slap, valve train noise and other noise as spark knock. NOISE ~ (D.C. Bias + KNOCK(A))*(1-exp(-KTS/RC)) + LAST NOISE where, NOISE is the noise threshold level"
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Post by fairmont on Feb 4, 2009 10:23:09 GMT -5
Thanks for the info's....
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Post by Matt Culpepper 2300gearjammer on Feb 4, 2009 13:21:51 GMT -5
If you hook a oscilloscope to the knock sensor you'd find it doesn't take very much to show a reading and lightly tapping on damn near anything attached to the engine can show up on a scope. I also either have solid mounts or very very firm motor mounts...so vibration can be bad.
Most of the engine det thats happens is below an audible level...so if its to a point where you hear it, its gotten pretty bad. The good thing with your car is whatever combo you have or want to build, someone has likely done it and established some safe limits. I stay well within the safe limits and do not run a knock sensor. With everything stock and running all over the page on an 1/8th track I went .2 faster and was very consistent just by disconnecting the knock. Timing was at 10* spout out, good replacement ign/fuel parts and boost at 20spi.
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Post by svojohn on Feb 4, 2009 14:57:13 GMT -5
If you hook a oscilloscope to the knock sensor you'd find it doesn't take very much to show a reading and lightly tapping on damn near anything attached to the engine can show up on a scope. Yes but will the EEC retard the timing?
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Post by Matt Culpepper 2300gearjammer on Feb 4, 2009 16:44:25 GMT -5
yeah I agree with what you are getting at. I can verify pretty easily. It does retard the timing on many vehicles but If its nice out this weekend I'll verify how much, if any, its effected on a completely stock svo...(if it starts still)
I'm not trying to push results either, I'm very curious and will take a non-biased approach. The only factual info I have is the 320k miles on the bolt-on engine with no knock sensor.
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Post by svojohn on Feb 4, 2009 19:50:31 GMT -5
Using the Tweecer RT and Binary Editor, I’m able to data log the EEC in realtime and see how much timing is being retarded from the knock sensor. It takes a very good hit to the intake manifold with a ball-peen hammer to trigger the knock retard. Even than it’s only a few degrees at best. The timing will retard 20 degrees if you can manage to get a full 5 volts out of the knock sensor. I’ve tuned on a number of different 2.3’s and the most knock retard I’ve seen was 10 degrees. It was always caused by the air/fuel being too rich. I’ll guarantee you if your air/fuel ratio is richer than 11.3 during peak torque, the knock sensor will turn on. When the tune is good, it never turns on.
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Post by Matt Culpepper 2300gearjammer on Feb 4, 2009 20:18:44 GMT -5
Thats sort of what I was thinking. I didn't expect a ton of timing to be pulled and the only thing I actually tested this on was a 97 gm truck via scan tool.
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Post by Stinger on Feb 5, 2009 15:40:07 GMT -5
It was always caused by the air/fuel being too rich. I’ll guarantee you if your air/fuel ratio is richer than 11.3 during peak torque, the knock sensor will turn on. So for all of the guys on this forum that have "stock" tunes which you and I both know are way richer than that at torque peak, what do you suggest? Unplugging it unlocks power more times than not for untuned 2.3's.
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Post by svojohn on Feb 5, 2009 16:28:23 GMT -5
It was always caused by the air/fuel being too rich. I’ll guarantee you if your air/fuel ratio is richer than 11.3 during peak torque, the knock sensor will turn on. So for all of the guys on this forum that have "stock" tunes which you and I both know are way richer than that at torque peak, what do you suggest? Unplugging it unlocks power more times than not for untuned 2.3's. Very true. I think they would be much better off if they used a chip and learned how to tune the engine than unplugging the knock sensor and listening for denotation.
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Post by Stinger on Feb 6, 2009 1:33:53 GMT -5
I agree with you on that, unfortunately that's either not an option for some, or they have no desire to learn...just want to plug in someone's tune and hope it works. In that case, if they have a good ear for detonation then unplugging the knock sensor will normally gain some power.
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Post by fairmont on Feb 6, 2009 12:37:03 GMT -5
Ok guy's i'm going with less timing and unplugged ks.... case closed. Thanks Stinger for your understanding.....
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