A/F Ratio adjust

Calibrations for FlashPro Manager - Use all calibrations at your own risk (dyno tuning recommended)

Post Reply
Posts: 1
Joined: Fri Mar 08, 2013 7:41 pm

A/F Ratio adjust

Post by macleanjosh »

Hey everyone. I'm currently looking for some help with a slight problem I am having with my tune on flashpro. I do have a tune, I got it from a buddy of mine with the same setup I have. It was started as a base map which he modified and tuned himself. The tune works great, no problems, I few knocks on cycl 2 and sometimes, but not all the time on cycl. 3.

The problem I am having, is my car is running rich. I don't know a whole lot about FP, but slowly learning. Looking at the sensor tables, its telling me my fuel ratio is 14.67. Is this high? I can smell the car running rich, and its eating up my gas, so I'm just looking for some basic steps I can take to lean it out some to save myself some money on the gas tank. Any help would be great. Thanks.
this is one of the graphs I am looking at.  memory serves me correctly, these lines should not be touching am I correct?
this is one of the graphs I am looking at. memory serves me correctly, these lines should not be touching am I correct?
Untitled.jpg (75.46 KiB) Viewed 4815 times

Posts: 34
Joined: Wed Mar 13, 2013 3:20 pm

Re: A/F Ratio adjust

Post by bigbadspoon »

I definitely recommend doing a lot of reading before you play with your base map any further.

14.7 A/F reading from your O2 sensor essentially means your car is burning exactly the correct amount of fuel for the amount of air going into it. The only reason to adjust this area of your table would be if your fuel trims were outside of an acceptable range (usually +/- 10%).

Also, lines crossing on the cam table (the one you screengrabbed) is OK. The fuel lines are not supposed to cross. One other thing I noticed is that your cam table goes up to 50 degrees right before VTEC. Does it continue at that value on the high cam table? If so, what cam angle is your car actually achieving in that range on your datalogs (over 5000 RPM, map over .950 kPa)? The entry for this value is called "CAM". I have been afraid to set mine over the stock 25 because I'm not sure if the higher valve lift causes a possible interference condition, though I have heard there is a software safegaurd built-in.

As to why your car smells like it might be burning a lot of gas, there could be a number of reasons. Are you running a setup with no catalytic converter? That will definitely make the car smell. If you're not, then you need to be looking at your A/F ratio during many different driving conditions. Typically, in closed loop, it should be floating pretty close to 14.7, with some peaks (over 14.7 during deceleration in gear; this number can max out pretty fast by design) and valleys (below 14.7 during acceleration, but returning quickly to 14.7 unless you're at WOT).

In general, the computer can compensate for some pretty huge screw ups and still achieve decent mileage while driving like crap. The only real way to boost your gas mileage is to be a better driver. On my stock Si, I have not really seen any mpg gains on my tune, with fuel trims consistently +/- 3%. Bumping the cam at cruising speed up to 35 degrees brought down my average injector pulse width by about .2 ms. A pretty minor gain, though.

From my own experience, I've averaged 34 mpg over the last 10k miles in my car with all season tires. I borrowed a couple of Si's from work with summer tires and got about 37 mpg on both of those. If you're doing a lot of highway driving, I'd say that's about the max you'll ever get.

Post Reply