Using HP Tuners to pull timing on nitrous

I had an idea and would like to either prove it out or discard it, and I'm sure some of you gurus might have wondered or figured it out. Since we have 2 timing tables, I wonder if there is a trick or technique to be able to consistently switch over from one timing table (say High Octane) to the other timing table (Low Octane) with the right trigger/enabler for nitrous use. Wild thought but for example, using a relay signal from the nitrous switch or window switch to feed a "fake knock signal" to the PCM and force going into the low octane table (which would be the now nitrous spark table).

Not sure how quick it would react, and it changes a lot more parameters than just timing.
But the sensor for ethanol content (e85) changes all kinds of timing and fueling parameters according to input.
Have a switch that reports one signal input for e10 then switch it to a value for e85 and map your parameter "adder" tables accordingly??

Most people just use a relay/resistor on the IAT signal wire. That allows you to modify the timing retard and the fueling based on the new false IAT reading.

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Originally Posted by Evo8john

Most people just use a relay/resistor on the IAT signal wire. That allows you to modify the timing retard and the fueling based on the new false IAT reading.

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Makes a lot of sense. And use the IAT spark retard tables accordingly. Even better because you keep the functionality of the knock sensors and low octane table. Pretty smart. I guess you could also use a resistor/relay on the Coolant Temp signal wire too, and keep IAT functionality during nitrous.

I could see getting yourself into some EOT tables messing with the ECT inputs. ECT plays roles in a lot of other functions than just spark advance. Imo, the IAT would be the safer bet to trick into pulling timing

Quote:

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Originally Posted by Evo8john

Most people just use a relay/resistor on the IAT signal wire. That allows you to modify the timing retard and the fueling based on the new false IAT reading.

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I second this works great!

I ended up using CLT instead of IAT in OL and works phenomenal; the nice thing is that because of the charge air temp bias being more heavily biased to IATs than ECTs, the AFR swing is minimal. I do however have one gremlin that I don't know how to solve it yet; when the nitrous hits and activates the relay bypassing the CLT and switching to the resistor (simulates about -14deg F), for whatever reason it also triggers the oil temp to read 'LOW' and even after a pull it doesn't recover immediately. Usually takes a couple of key cycles and driving for the Oil Temp to read back normally and not mark 'LOW' on the gauge. CLT recovers to normal immediately though. I don't understand the connection between the two, unless it's something in the OS that when CLT reads excessively low it automatically forces the oil temp gauge data to override the sender and just read 'LOW', that's my theory at least.