Ready To Start
There are three phases to getting your EFI system dialed in.
* The first start
* Dialing in the cold-start and idle settings
* On-the-road tuning
The F.A.S.T. software uses...
The F.A.S.T. software uses "dashboards," which can be configured to view various parameters. Most of the screens have default dashboards. Using a dashboard, you check that the TPS position is less than 10 percent at closed throttle and goes up as you open the throttle. The MAP sensor (vacuum) should be approximately 100 KPA. The air and coolant sensors should read approximately the ambient temperature, and rpm will show 0, but during cranking this should show cranking rpm.
The F.A.S.T. system uses tables or maps to allow tuning the EFI and ignition timing. For the first start, make sure the crankshaft reference angle is correct. I usually set the ignition table to all one number such as 20 degrees. This will fix the timing so it won't jump around. Then when the engine fires I use a timing light while I change the crankshaft reference angle value until I get 20 degrees.
From there, adjust the cold start tables in order to keep the engine happy while it warms up. I usually do the initial tuning in open loop so I'm not fighting the ECU. Also, make sure the TPS value is below the point that the system detects you are no longer at idle.
It's a waste of time to try adjusting the basic fuel table until the engine is warmed up and stabilized. This is because the F.A.S.T. system uses warm-up tables that overlay the basic fuel table. You can't set the basic table until the warm-up has been achieved and those tables are no longer adding fuel.
The Basic Fuel Table
Now we look at the most important table in the F.A.S.T. software-the VE table. VE means volumetric efficiency and is a measure of how much of the intake charge is available for combustion. A higher VE value will require more fuel, and will therefore enrich the mixture, thereby bringing down the air/fuel ratio. Typical VE ratios run between 40 percent for a normally aspirated engine at idle, to 100 percent when producing full power. Supercharged engines produce well over 100 percent because the charge is forced in, and is therefore more than the engine could normally do on its own.
Don't let the numbers confuse you. These are not injector pulse widths; they're the VE values with the vertical axis being manifold pressure or vacuum and the horizontal axis being rpm. One hundred KPA equates to approximately zero manifold vacuum (wide-open throttle), and a 0 KPA being approximately 15 inches vacuum.
At all times you get a 3D representation of this table. This is a good visual aid to see if there are any weird spikes or table locations that don't make sense.
Final Tuning In The Car
By the time you've reached this point, you should have an engine that starts, warms up, and idles. But you have not done anything for the load conditions. Once you've verified and entered the correct crankshaft reference angle, then you would change the spark table to represent a typical spark curve. This Hemi belongs to a customer who wanted a roller cam and some serious rpm capability. This is not a typical cam we would choose for the a street application, nor would we typically use a Jesel belt drive on the street, so the numbers we ended up with for the EFI were a little different from what you would normally see.
There are several other tables where you would adjust fuel delivery as a function of the changes in manifold vacuum or throttle position. These emulate the accelerator pump. But I don't change any of these tables until the engine is in the car and I can drive it.