hey guys,
i dont know if anyone reads chevy high performance magazine but if you do you know about the cavalier project car they are building. they have a turbo on it running right around 8 lbs. of boost and they came up with an idea that gave them a honest gain. they went to radio shack and bought a 100 ohm resistor and placed it in the knock sensor. i was suprised cause i recently posted a question pertaining to this subject since i noticed on my scantool my knock retard was take 6 degrees of timing out under boost which is killing some horsepower. they were also saying in the article that the reason why the stock knock sensors do this is because they are extremely sensitive. they were saying that something as simple as puting polyurethane bushings in the motor and tranny mounts will set it off. i am gunna try it this weekend, just picked up the resistor at radio shack this afternoon for a buck. this has been getting to me everytime i see it take timing out under full throttle, i know i have the engine tuned correctly cause i am running 11.5 to1 A/F Ratio under boost according to my Innovative wideband. well guys, if anyone has any info. they would like to add, go ahead......maybe this is a new secret trick for us boosted j's.... lets hope so. i am heading to the track the 29th for sport compact shootout night so we''ll see what she puts down now. later guys
could this possibly work?
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they did it, i guess we'll find out
hehehe....this is something were gonna be trying next monday and tuesday when my car gets its next 8+hrs of dyno tuning...cause i saw about 3 degrees of retard at anything over 8PSI. not that that would be a bad thing...LOL
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Yes I read the same article in Chevy High Performance. It was actually soem from RKSport who did this. I'm also wondering if this would help Ecotecs with Cams.
FU Tuning
Am I reading this as you are using the resistor in place of the KS? As in the IAT trick? Or is it wired in the lead to the sensor?
Very curious. I have LZM Stage 2 Cams with no codes (one p0172 but thats it and once at that), with all the mounts........
2006 Cobalt SS I/H/E ZZP S2 HPT 2.8/60's Etc...13.8@105(I need to learn how to launch)
Knock sensor pulling timing kills hp but saves your motor.........
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My knock sensor reads about .08 - .09 more volts after I put in the motor mounts. Before mounts, my SAFC knock sensor never went over 20 with a 20 correction (.04v), but now I see 80-90 all the time. I still get a significant timing advance at WOT though.
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I'd try a tank of premium and see if it makes a difference, if you're not already running premium. I was able to get rid of my 5-6 degrees of knock retard by running premium, and adding "water wetter" to my coolant, no knock sensor tricks.
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anyone here running about 6psi with emange, and would share their timing map?
im just wondering i havent adjusted my timing at all, all i have is it retart 1 degree in boost thats all i have cause i wasnt sure ....anyone give me some tips
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my car with out boost sees as high as 6 according to the aero force scan gauge
and its the same with or with out higher octane
you can also make the knock sensor less sensitive but loosining the tq setting on it some
The knock sensor is just a microphone. It's tuned to a specific frequency to pick out knock over other sounds. By putting in a resistor you are essentially turning the volume down on the mic. If you had an engine with internal mods like high lift cams and/ or forged pistons that added noise, this makes some sense. But on a stock or close to stock engine with boost added, nothing has changed to add a significant amount of knock. If the ks says something is happening, it's probably detonation.
Skilz10179 is right.
Quote:
Knock sensor pulling timing kills hp but saves your motor.........
-->Slow
well then maybe thats my prob, i am running wiseco forged pistons with all the mounts and forced induction. but i DO run nothing but premium gas and i know i have the A/F Ratio correct. i am gunna try this trick this weekend and see what happens i think. i love when we find out these little tricks like this dont you guys...
hmm maybe this is why ive become slower after diff motor mounts
1989 Turbo Trans Am #82, 2007 Cobalt SS G85
man i am excited to find out what happens, i might actually do it tonight after work if my dad will let me sneek on the lift before close.....i guess we'll see
I am curious too, I wonder if a 50 ohm would be safer?
Again, how is it wired up? Along with the wiring?
2006 Cobalt SS I/H/E ZZP S2 HPT 2.8/60's Etc...13.8@105(I need to learn how to launch)
slowolej wrote:The knock sensor is just a microphone. It's tuned to a specific frequency to pick out knock over other sounds. By putting in a resistor you are essentially turning the volume down on the mic. If you had an engine with internal mods like high lift cams and/ or forged pistons that added noise, this makes some sense. But on a stock or close to stock engine with boost added, nothing has changed to add a significant amount of knock. If the ks says something is happening, it's probably detonation.
Skilz10179 is right.
Quote:
Knock sensor pulling timing kills hp but saves your motor.........
-->Slow
Correct it is.
What you are not getting is modding a motor with mounts, cams etc... can cause extra vibes, which the KS could pick up. Also a turbo can add extra vibes as well. At the same time I'm not saying everyone with a boosted car should do this. That is not so. It should be done with lots of research, and knowing air/fuel etc... The people at Chevy High performance are not just trying to blow people's crap up.
From all the other post for n/a ecotecs having problems with cams and codes, it does seem maybe the KS is too picky. Also some people have had problems with 2.4's when they had the tranny mounts as well. That causes lots of vibes.
FU Tuning
Interesting mod. But the KS can safe our engines in some cases. We need some good research and dyno tuning to know it really work and when begins to be useful. Otherwise is like to drive blind.
GM shoud had done the homework about this mod, then maybe a 100Ohm resistor would make the KS less sensitive some % enough to be safe and free up some HP. Of course under specific conditions. People, I haven't find the article yet, but I am pretty sure that this non-stock EcoTec engine has some specific parts that can take a benefit from this mod. Any other way doesn't have sense.
I like cheap HP, but safely.
Just my point of view.
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People have been fooling the knock sensor for years. I've seen some very noisy engines not cause enough knock signal for the computer to have a problem. The old time trick was to wrap the knock sensor threads in teflon tape to mute the sounds. A resistor wasn't used because GM started looks for the voltage on the ks line to be within a range of accepted values. Adding a resistor can move the voltage above or below this range and set a code.
Why not research the part numbers for the 2.0 SC ks and the 2.2 Eco ks and see if they're the same? If they're different then try just swapping the 2.0 sensor in and seeing what that does. It's a better guess than a resistor imo.
-->Slow
