Ideal fuel trim settings??

[nmstang]

I have been working on the tune for my 2007 v6 mustang with the U7145. I have settled on the 91 octane steeda tune and thought it was just a little rich. Yesterday we ran diagnostics and the computer was adding 8% at idle and quite a bit more at normal driving speeds. We went in and ended up adding 17% more fuel. On the trip home the long term trim stayed at or around 0% and I was wondering if this was the ideal or if your performance tunes ran to the lean side. I was getting lean codes and really soft shifts with the 93 octane tune and it looks like I was very near lean codes with the steeda tune. The car runs a lot smoother and sounds better with the added fuel. Thank you for your help.

[christina]

What is done to your vehicle? Also, what revision of the Predator are you on?

[nmstang]

I installed a MAC Performance cold air intake with 83.5 mm venturi and ceramic coated shorty headers and catback stainless duals all from Mac Performance. I am using the latest version on the U7145.

[christina]

Try installing the Performance Tune and add 5% to the Global MAF curve.

[nmstang]

Christy, I initially installed the performance tune and it gave me lean codes as well as really soft shifts.I think your performance tune runs leaner than the Steeda 91 tune because I ran it for 300 miles without any lean codes. We have tried all the tunes in the tuner and the 91 steeda is the best performer. My question is: Would the goal be to have the computer trim as little as possible or do you get better performance running lean and having the onboard computer adding fuel all the time? This is a huge air intake, I think it was designed for a v8 but we are going to supercharge it in the future so we set it up with that in mind. Thanks for your help.

[nmstang]

I revised the post above...

[christina]

The DIablo tune will run leaner than the Steeda tune, as the Diablo tune is designed for a stock intake. It cannot accommodate for all of the extra air coming in. Also, the Steeda tune has a firm shift option, which you are probably using. The goal is to have fuel trims as close to 0 as possible. There is no MAC tune in the Predator so you can either adjust the tunes with the Predator (using a wideband for this is HIGHLY recommended) or you can get to a CMR dealer and have them create one (for an easy custom tune, try Dallas Mustang at www.1800mustang.com).

[nmstang]

Thank you very much for your prompt reply! That is the exact information I needed. Again Thanks