Question: Engine -> Airflow -> Electronic Throttle Tables
I'm having an issue with my car. I've installed a cam and now when I'm at red lights or stop signs, in drive and my foot on the break, the car will jerk back a forth a bit. The shop that did the install did a number of tunes to work on the issue but it's still not perfect. In another thread, I posted the tune files and someone noticed that my Airflow, Small Range and Large Range tables have never been posted. This tuner suggested I make the following changes:
Engine -> Airflow -> Electronic Throttle -> Airflow Multiple rows 0.00-0.90 by 5% (x 1.05).
Engine -> Airflow -> Electronic Throttle -> Small Range Multiple the entire table by 95% (x .95).
Engine -> Airflow -> Electronic Throttle -> Large Range Multiple rows 0-554 by 95% (x .95).
This is my answer to that idea:
If I'm looking at these tables correctly, here's what I think is happening. The gas pedal in this car is a throttle by wire system. Thus, when I push on the gas pedal, I'm actually increasing the voltage that's flowing to the throttle body. For the airflow table, as we increase the voltage, we're opening the throttle body wider. By increasing rows 0 to 0.9, we're telling the vehicle that at these lower levels of throttle, open the throttle body 5% more than the stock settings. Also, it looks like max throttle voltage is 3.8 volts so 0 to 0.9 is actually everything from 0% to 25% throttle. Am I on the right track? What effect will this have during driving? In my test drives, typical driving for me is virtually always below 25% throttle. Sure. I get on it from time to time but just regular driving with traffic all around me and I can't go crazy, I'm pretty much always going to be less than 25% throttle. What will that increased airflow do to the air/fuel mixture and engine performance?
As for the Small and Large Range tables, this looks kind of like the inverse of the Airflow table. These two tables seem to actually represent one table as the Small Range values live between the 6 to 554 rows on the Large Range table. By having two tables, it's allowing us to have finer control at lower throttle. By decreasing everything on the Small and everything up to 554 on the Large, we're saying that when the airflow is this much pounds-per-hour, this is where the throttle voltage should be on the gas pedal. By increasing the 0% to 25% on the airflow table, we need to make up for that by decreasing the relative values on these two tables.
Am I making sense and following along with what's happening?
And again, the big ask here, what's the risk, if any, to my car. If I upload this modification and start the car, what's the worse thing that could possibly happen? I'm not afraid to admit that I'm a bit scared to do something like this without knowing the answer to this question. Many, many thanks for everyone's time on this.
