So I have did a lot of reading on this topic, and I've tried all the methods I've heard of. Once and for all I'd like to hear some real results from other tuners who have had success with their methods as well as the negative side (if any) for each method.
The first method I would say is the IAT timing trick. Its a simple concept and seems to work....but I hear that it will effect fueling on SD tunes. My question is this: If you wire the relay to trigger only while the solenoids are powered what difference would this make? Wouldn't the change that it may make to the NA tune just get soaked up with tuning via the fuel jet or fuel pressure if using a standalone? Are people saying that the change from a day when the iat was truely something like 40 degrees compared to 100 degrees create a drastic difference in the final afr? How much would the afr really change?
Second is the TCS timing tables. Send ground to the appropriate pin of the pcm and you have a tuneable timing retard table....or do you? I just tried this on a 2000 SS Camaro and the timing retard doesn't remain on for the entire duration of the run. The retard goes away even though we confirmed that the ground was still present for the entire run. Its my understanding that certain vehicles/os may have a time maximum for this, but the 2000 camaro does not to my knowledge.
Third, is the 2 bar os method. Wire a relay to slam 5 volts to the map sensor when activated. This I have read will allow you to tune the fuel via the ve table in the bottom row. Also, I have read it will register more airflow so that the timing will dip farther down into the table allowing for timing to be pulled out right on the main table. I tried this for the first time today. For a dry system, I'm sure it would work as advertised, but I'm tuning wet. I did get it to work properly and logged 210 kpa while the relay was active. While making test pulls with the nitrous bottle closed and the standalone un-plugged I quickly realized I needed to cut the values in the VE for the 210 row in half. Once I did this the afr was really close to where it was making a normal NA pull up in the 95 and 100 kpa rows.
With the afr correct, the g/cyl was pretty much the same in the 210 kpa row as it was in the 95 row. Therefore, simply changing to the 2 bar didn't seem to give me the ability to alter timing for the nitrous at all. I went ahead and pulled a safe amount of timing in the main table and proceeded to spray the car. Again, no real change to the g/cyl of airflow. There was a pretty nasty lean spike at the hit, so I raised the figures in the 210 kpa row and appropriate rpm range and all the sudden the g/cyl jumped up a fair amount.
Now I'm sure for a dry kit having these numbers jacked up a good bit more than 50% of what the values are in the 95/100 kpa rows would allow you to tune for timing retard....but in my case, the car was overly rich after that initial lean spike, and I don't really want to lower the fuel supply via the fuel jets or pressure as they are supplying race fuel while I have 93 pump gas in the primary tank.
Sooo, is there something I'm missing or am I left to fine tune the fuel with this method and then doing the iat resistor mod anyway to get a control over the timing? The car has a 300 shot on it, so its not like we can just pull the timing in the main table for all conditions and live with the hp loss.