So we are getting started on a '12 Camaro 3.6 with a Nitrous Outlet plate on it.
I was looking at the IAT spark table and noticed it is all 0's.
We're looking at 100 hp wet shot. Should we just drop 3-4 degrees from the high load cels in the spark table and go from there? or try to use the IAT spark table?
This car ended up taking a large reduction in spark to keep KR under control. Since nobody chimed in I left the IAT alone. Thanks.
For a dry shoot, you can use the IAT to adjust timing since the dry shoot passes by the IAT sensor.
Wet Shoot I would go in high Octane table and fine the safe timing for the 100 shoot. just fine the safe timing for your wet shoot and run it safe rich WOT that works for your car.
I am running a 100hp wet shot on my 13 with all the bolt on's. I paid Norris Motorsports in Indy (since I am new to this and trying to learn it) and I know he set mine for a 4 degree retard only on the top end according to him. I do notice now that it doesn't seem to have quite the "snap" it used to have (running it just on the street without NOS) and he explains to me that it's because of the top end retard. Kinda miss the "higher" overdrive sound of the engine and little extra power (at least it felt like) when I floor it. But would rather not damage the engine when spraying.
I would try wiring the switch in line with a resistor to the coolant temperature sensor set for an extreamly cold range that you likely will never actually witness. You could set up the spark modifier tables to retard timing the desired ammount, but only in that area as well as fuel modifier tables if you need more finite adjustment on top of whatever fuel those jets allow to get sprayed/sucked in. Kind of like the best of both worlds.Originally Posted by SkilerB
Last edited by Dr. Nopps; 10-09-2015 at 07:53 PM.
resistor to IAT would be a better idea
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We have tried again using IAT spark. Because the normal driving was a little weak with so much spark gone. This car has one of those throttle floppers from Vitesse.
So I go back and restore all the top end spark from before the NOS. drive it again and get rid of the kr. Why do these have so much KR?
Anyway noticed in the logs that the spark drops like we want when the solenoids fire and the IAT drops. Only problem is that it starts climbing back up in short time. And seems like we only got about half of the retard. Working on the modifier tables hoping that will work.
Not having any luck with this IAT spark reduction. I can see the IAT switching low, but the spark is usually right around a few degrees less than the high octane spark table. KR all over the place. Now we have a new issue that needs addressed. There is an unwanted lean spot when the NOS comes on (We upped the hp on the jets). Might have to put smaller NOS jet. Bigger fuel jet does not help. Moving the fuel solenoid closer to the plate does not help. Ramping up the PE doesn't seem to help enough either.
Shouldn't Knock Learn be controlling the amount of KR automatically as needed? Or do you have it disabled?
How is the Knock Learn supposed to work?
I raised the Knock Learn IAT to -12 or something from -40 so it might not be affecting my desired spark while the NOS sprays. Didn't seem to matter.
No matter how low I go on the spark table this car shows tons of KR. I've since gone back up to where it runs good. Because I don't believe the knock is real unless I hear it any more. Fuel and spark seem to have no effect unless I go too rich and then I can hear a fuel knock and feel less power.
I think it's probably going to need a progressive for the nos. I have moved the fuel solenoid closer to the plate. There's just too long of a delay before the fuel gets through the plate and into the plenum. I have gotten very aggressive on the PE in that area to help take up the delay with the EFI but it's not enough.
Knock learn is supposed to detect knock, reduce timing to combat it and "remember" where the knock was experienced so that it can automatically reduce timing if those same conditions are met in the future. Knock learn starts off using the timing value in your high octane timing table. As it experiences knock, it slowly moves towards the timing value in the low octane timing table (for the RPM/airmass where you are experiencing knock).
So, for example, if I experience knock at 4000RPM @ .48 airmass, knock learn will reduce timing (by moving towards the low octane table value) until the knock goes away and remember that it experienced knock at that RPM/airmass, how far it had to move towards the low octane timing table in order to stop the knock and then automatically pull that same amount of timing again in the future when those same conditions are met - in an effort to avoid the knock in the future.
Now if those same conditions are met in the future and no knock is experienced, it will slowly move back towards the timing value in the high octane timing table until it experiences knock again under those conditions.
It seems that manufacturers use this in order to set the timing as high as possible under the perfect conditions and then let the knock learn mechanism reduce timing if/when needed (and "remember" this data for future).
So I would think that if you constantly experienced knock under certain conditions (regardless of NOS), the computer woud automatically adjust the timing as needed to remove the knock.
At least, that is my understanding. If anyone with more experience has any corrections, please do so! Also, you can log the Knock Learn Factor PID to monitor the status of knock learn and see exactly how it works.
In regards to tuning, you can tune the conditions under when knock learn is even attempted (RPM, MAP, ECT and IAT) as well as how qucikly it pulls and returns timing and the amount of KR required for it move towards the low octane table (or move back towards the high octane table). The knock learn value initially uses the high-octane timing table and as it experiences knock, it lowers the timing by moving towards the low-octane timing table. If your high and low octane tables are the same, then knock learn will have no effect. That may be the issue in your case - I think I remember your high and low octane tables being identical (could be wrong about that though).
Last edited by jtrosky; 11-24-2015 at 05:59 AM.
Thanks for the info. No the octane tables are not same. In fact I made sure the low octane table was at least 4 degrees lower than the high octane so that it could do it's job.
Regarding the knock learn. So is it possible that the seemingly excessive amounts of KR being recorded might diminish after some miles are put on the tune? IN other words. Am I seeing a lot by design because I am rapidly changing calibrations trying to eliminate it? Not giving it enough time to learn? Would there be any ill effects from continuing to work on the high octane table until there is little or no more KR? Seems like there shouldn't be.
I'm curious - how many degrees of KR are you talking about when you say that there is "KR all over the place"?
Also, I'd like to get a more experienced tuner involved before telling you to just drive it and give Knock Learn a chance to fix things. I know nothing about NOS and don't want to steer you wrong here!
But the amount of retard that you are seeing will be helpful as well.
I will say this, I do experience more KR right after I modify my tune. The computer does eventually learn to remove most KR via knock learn over time. Every time you rewrite the calibration, the knock learn value gets reset. Try logging knock learn PID so that you can see what it's doing.
Last edited by jtrosky; 11-25-2015 at 10:55 AM.
Regular driving with no NOS spraying. There was considerable KR especially around 2-3,000 and .60 cyl air. I attribute that to the characteristics of the "throttle flopper". Lowered high octane table to about 18-19 degrees in that area. Now there is no more KR driving under load. And she seems to run well and like it.
NOS is a different story. No matter how much fuel or spark +/- it gets there are spikes up to 8 deg. 0-5 dgrees and 10 AFR to 15-20 degrees with 12 AFR. It's only for a split second as I let off right away trying to get it resolved. We are currently going to install an air/oil separator to see if that helps.
Well we got that air/oil separator on there. And started experimenting with the tune some more. Looks like the IAT spark is not doing anything. Not sure why. Is it possible that even though there is an IAT spark table it may not be in play for some reason we are not aware of? In other words, it's just not going to work, ever?
Also, I am having a hard time finding facts about the normal operation of the fuel supply system. Specifically what the normal operating pressure should be. The info I find states fuel pressure should be 50-94 PSI. my next move is to install a mechanical pressure gauge and see what I am actually getting.
Another thing I have noticed is if I go to Engine>Torque Management>Engine>Driver Demand>Map A, Map B, Map C all have the "Modify at your own risk" warning on them. I read that you may need to raise the tables upper limits to get more power. What is the story with that?
OK tested the actual fuel rail pressure. It varies greatly. Waaay too much to be used as the supply for a simple wet system. So this thing is going to need a separate regulator or dedicated fuel supply system for the NOS to be predictable and tuneable. Unless, the fuel system settings can be manipulated for our purpose without causing trouble in other areas. If I go to Fuel System>General>Desired Pressure it looks like we can modify the behavior of the fuel supply system pressure. Has anybody done this before? It looks like I could set the values to 58 PSI in all areas and eliminate unwanted pressure changes.
hate to thread jack but, im just starting to mess with my friends v6 ive been tuning my solstice and this thing is a completely different monster. would one of you guys mind if i pmd you about some things on tuning a v6? thanks
Well the Desired Pressure change smoothed out the NOS fuel flow problem.
Has anyone been able to use the IAT spark table? If yes, what's the trick? If no, is there another way to manipulate spark when we spray?
I've used the IAT spark table on my 2012 Impala (3.6L LFX & 6T70 trans) and it seemed to work as expected. You can actually log how much timing is being pulled per the IAT table (there is a specific PID for it). Seemed to work when I was messing with it... I'm not currently using it anymore though. I was using it to combat KR at really high IAT temps...
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