I use LT1 Edit and I recently started looking through other peoples tunes to see what kinds of things they change for a bolt on car. I also found the link below. I noticed that many of the PE tables start out richer and then have a downward curve and go leaner as the RPM increases. These are very different than the stock PE table which adds more fuel as the RPM increases. The stock table makes more sense to me since there is more demand for fuel as you approach peak power.

Why do many of the tunes I see have a downward curve???? Is this just what needs to be done to get a constant AFR at WOT or is there some other reason for leaning it out as the RPM increases??
Any info appreciated.

http://carprogrammer.com/Z28/PCM/PE/...omparison.html

Thanks.

 

The stock PE tuning is way too rich, generally targetting about 11.7:1 at WOT. You want something closer to 12.8-13.2:1.

 

The stock tune can be a little confusing in this aspect. Looking at the PE curve doesn't tell you much about the air fuel ratio since those are just values. There is really no formula to take those values and calculate the real air fuel ratio. The only way to find out how that PE curve affect the air fuel ratio is through the use of a wideband o2 sensor. As already mentioned, the stock tune is rich from factory, which explains why you see so many tunes that are leaned out.

 

sorry to post hijack but do you generally want a 12.8-13.2:1 a/f ratio throughout the rpm band? Or should it be more rich at higher rpms? Im confused with the stock tables. And i dont want to blow up my engine by leaning it out tooo much.