Crank the engine while observing the monitor. The RPM reading should change to “Syncing.” Within a few seconds this should change to whatever the engine RPM is. If the engine doesn’t start and come to an idle, go to Holley’s troubleshooting guide
and fix the problem. Check for leaks as the engine warms up and top off the coolant if needed.
On the handheld, surf through the Monitor, Multi Gauge and then the Air/Fuel Ratio screens.
• AFR, A/F-This should read the air/fuel ratio the O2 sensor is reading. The reading may fluctuate a bit as the engine runs and warms up.
• Target Air/Fuel Ratio-This is what the ECU is trying to maintain as the a/f ratio and will change depending on engine load and speed and coolant temp.
• Coolant Enr, %-This tells you how much of the enrichment the system is adding is based upon coolant temp as a percentage. Once the engine reaches 160 degrees this should read 100 indicating zero enrichment.
• CL Status-Indicates Closed or Open loop operation. Closed means the Sniper ECU is in full control and is controlling the a/f ratio. The Sniper ECU should always be in Closed Loop once the engine reaches 160 degrees.
• CL Comp, %-This tells you the percentage of fuel delivery control the ECU is exerting. A negative number indicates leaning out while positive shows enrichment. In Open Loop during warmup this will read zero.
• Learn Status-Indicates whether the Sniper ECU has entered its self-tuning status. This should always read “Learn” once the engine has reached 160 degrees and the ECU has entered Closed Loop if Self Tuning has been enabled (this is the default). If this has been disabled or the ECU is in Open Loop this will read “NoLearn.”
• Current Learn, %-This should read between -20% and 20% and indicates how much fuel is being added or subtracted based upon the base fuel map in the ECU memory. This can read higher or lower depending on several parameters.
• Inj PW, msec-This is the injector pulsewidth in milliseconds. Innjector pulsewidth is the length of time the injector is open and injecting fuel and will vary depending on engine speed, load, and environmental conditions.
• RPM, rpm-Engine speed.
• Fuel Flow, lb/hr-This is how much fuel is going into your engine as an instantaneous reading. A gallon of gasoline weighs about six pounds.
Set the Idle
Go back to the Initial Startup screen. Set the parking brake and put the transmission in Neutral. Adjust the idle screw until the IAC Position reads between two and 10 percent. Now adjust the idle speed screw (also called the throttle plate screw) while watching the TPS value. If the value increases, cycle the ignition to reset it to zero. Continue this until the target idle speed has been reached.
Go for a Drive
Head back to the Air/Fuel Ratio screen on the handheld. With the engine at operating temp and the brake set, put the transmission into gear (automatics) and turn on the A/C. Once the CL Comp value returns to zero, you can turn off the aircon if you want and head off for a drive.
Don’t jackrabbit from stops. If you have a manual transmission, take longer than normal to disengage the clutch for a bit. Hit and hold city street speeds for a few minutes, then vary your speed a bit for a few minutes until the Comp value returns to zero.
Now head somewhere that you can safely do some harder acceleration, including a few wide open throttle (WOT) blasts. You’ve just put the engine through several speed and load variations to teach the ECU. Your Sniper EFI’s ECU will have lowered the Learn Comp Limits enough to transfer the new fuel map to the base map. This will continue to happen as overall driving conditions change and stabilize - for instance, a change in air temp of more than 10 degrees, or if you spend a week in the mountains.
Enjoy. Let us know what you think about the Sniper EFI for the Jeep CJ with BBD carburetor in the comments below.