F.A.S.T tuning, general question

[JonS]

Two general questions ...

So the F.A.S.T is installed and I log the first 1/4 miles pass. Having this data, what changes are made? What are some of the tuning processes that you guys are using as the logs are reviewed?

For part throttle and logging daily driving ... What tuning processes have proven to work? (from looking at the logs to making actual table changes)

Thanks
J

 

[bobc455]

When I review a log after a run, the first thing I do is make sure that the A/F ratio stayed where I wanted it. Then, I play back the log on the VE table, and tweak the VE table as needed to get it "dead on".

If you have a knock sensor, you can retard the timing in any cells where knock may have showed up.

Other tuning includes playing with the A/F ratio a bit to see where you get optimal 1/4 miles, and playing with the timing also. These aren't really derived from the log, but usually a before/after comparison when you make a change. (One nice thing about the FAST is that it allows you to start tuning A/F ratio before your VE table is perfect.)

Eventually you find the sweet spots and leave it alone. When you are all dialed in, some people like to disable the O2 sensor to get the best consistency, and just review the logs occasionally to make sure everything is functioning properly (i.e. if you see a lot of O2 correction at high RPMS then your fuel pump may be failing, etc.).

For part throttle / daily driving, it's more of a real-time activity- if you can get a partner to drive the car, you can play with the VE tables until you get them dialed in to be accurate. Then you play with timing & A/F ratio to get best drivability at each point on the table. (This is a process that requires being in the car, it's not really possible to tune for drivability from a computer alone. You have to see if it stumbles or pings or whatever as you're driving, or on a dyno.)

-Bob Cunningham
bobc@gnttype.org