S&S Cycle EZFI - Manual (Page 4)

4
BASIC TUNING TIPS
Now that you have EZFI™ installed and understand how to operate it, you are ready to tune. Here are some basic tips to make tuning with EZFI faster
and more productive.
Take notes.
Tuning while riding is not a safe practice. If the engine hesitates, surges, or doesn’t run right, make a mental note of which operating range it is
occurring in. Just keep tabs on the RPM, throttle position (cruising at part throttle or accelerating hard at wide open throttle?) and the behavior
(surging, sluggish response, missing, etc.) Then at a safe spot, pull over and write down your notes.
Warm up the engine before tuning.
Starting your tuning session with a warm engine minimizes the amount of temperature compensation that the stock ECM might be adding in. It also
ensures repetitive results. If you tune the motorcycle with the engine cold, you will probably end up re-tuning it later when it’s warm.
If possible, measure what the engine is doing.
The fastest method of tuning requires wide band air fuel ratio (AFR) measurements. There are numerous stand-alone wideband systems available,
which can be operated while riding the motorcycle. Most tuning centers are equipped with wideband systems, which usually analyze the AFR
using a sensor inserted into the exhaust pipe. Either method will provide better data than “seat of the pants” interpretations of engine operation.
Knowledge of the AFR at various operating points allows you to dial in the precise fuel adjustments necessary to hit your target AFR.
Know your symptoms.
Adding fuel does not solve all running problems. Many engine modifications will require a reduction in the amount of fuel at certain operating points
for optimal tuning. Don’t be afraid to take fuel away.
Coughing or surging usually indicate a lean condition. These conditions will require adding fuel to correct. Measuring your AFR with a wideband
system will give much better results than trying to diagnose the symptoms.
Tuning on Closed Loop Vehicles.
Tuning for performance modifications on a 2006 Harley-Davidson® Dyna™ and any 2007 model is more difficult because the ECMs on these
motorcycles run closed loop fuel control. This means that the ECM uses feedback from oxygen sensors to continuously re-calculate the amount
of fuel needed at each operating point. In general, most stock ECMs target a near-stoichiometric (14.6) air fuel ratio (AFR) for the operating range
of 0 to 4500 RPM and 0 to 80% throttle. If you use EZFI to alter the fuel amount in this range, the stock ECM will undo your change to force the AFR to its
14.6 target.
For example, if you are in the low cruise range of 1500 RPM and 15% throttle, the ECM will target a 14.6 AFR. If you tune +10% fuel to target a richer
AFR, the ECM will detect this extra fuel and reduce it’s base fuel amount to return the AFR back to 14.6.
There are two options for tuning closed loop motorcycles. Both achieve the same result. The first is to do nothing and let the stock ECM add or
remove up to 30% fuel to meet its target AFR. Don’t tune within the stock closed-loop range defined above. This roughly corresponds to EZFI modes
1, 2, and 3. Leave the adjustment in these three modes at 0. Let the ECM run closed-loop to target its programmed AFR. Tune the remaining modes,
4 – 9, for wide open throttle conditions.
Your second tuning option is to use EZFI to zero out the ECM's adjustments. Highly modified engines may require more fuel than the stock
closed loop system can compensate for. The main reason to do this is if the stock ECM is running out of fuel adjustment and setting the Check
Engine light. This would only be necessary on the most extreme engine modifications, where fuel delivery requirements are drastically different
from the stock engine.
Table 4 - Operating Ranges for Mode Switch Settings
Mode Switch
Position
Adjustment Range
0 None – display off
1 Idle, 750 to 1250 RPM, closed throttle
2 Low cruise, 1250 to 2000 RPM, 2.5% to 50% throttle
3 High cruise, 2000 to 3750 RPM, 2.5% to 50% throttle
4 Wide Open 1250 to 2000 RPM, 50% to 100% throttle
5 Wide Open 2000 to 2750 RPM, 50% to 100% throttle
6 Wide Open 2750 to 3750 RPM, 50% to 100% throttle
7 Wide Open 3750 to 4750 RPM, 50% to 100% throttle
8 Wide Open 4750 to 6500 RPM, 50% to 100% throttle
9 Acceleration enrichment Picture 2
Mode Switch
Up/Down Buttons
Negative LED Value LED