• Check fuses (& correct amperage fuses), relays and their sockets. Fuel pump wiring too.
• Is the ECU main power & ground wired directly to the battery? Battery acts as a great capacitor/filter. (LINK & LINK)
• Cable from negative battery post to engine block, engine block to frame and #8 AWG wire from body to battery? (LINK)
• Check the switched (keyed) 12 volt red/white wire connection. 12 volt ignition power too. Very important!
• Is the System Relay sending 12 volts to the (red) fuel injector wire and to the (green) fuel pump trigger wire? (LINK)
• Inspect the entire wire harness for chafing against metal. Check ignition switch too. Custom I/O wired correctly?
• Perform a "wiggle test" on the entire wire harness/connectors from ECU to engine and Ohms continuity tests.
• Is a shielded wiring harness used with the crank and/or cam sensors? Magnetic sensors at least need twisted wires.
• Try completely disconnecting the battery for 20 minutes. This "resets" some unusual ECU issues.
• Reflash ECU firmware to erase large capacity of internal datalogs that won't Delete. "Delete All" reformats the memory.
• Completely remove corrupted EFI software from "Control Panel", "Documents", "C:Drive", and install a fresh download.
• Does the laptop have the latest software & USB drivers? (https://www.holley.com/support/resou...Fuel_Injection)
• Does the ECU have the latest firmware? (https://www.holley.com/support/resou...Fuel_Injection)
• Are there any high voltage/noisy electrical components near the EFI wire harness or sensitive actuators/sensors?
Resistor type spark plugs & good wires should be used with an EFI system, to suppress electrical noise/interference.
• Did the routing of the spark plug wires change at all? Are plug wires in good condition? Check rotor phasing too.
• Is there something (accessory/component) that turns on or off, when the EFI malfunctions?
• Don't tune on the hand-held/TSLCD and a laptop. Both can be connected but use one or the other to edit/tune with.
• Ensure the ignition timing is synchronized. Review datalog for RPM Errors. Record a System Log if necessary.
• Erroneously set "Warning Enabled Timing Offset" parameters in the "Sensor Scaling/Warnings" (System ICF, I/O ICF)?
• Ensure the Inductive Delay is also accurately adjusted. If it's way off, driveability, power & misfires can result (LINK).
• Does the Data Monitor display a legitimate RPM reading while cranking? If not, there's no RPM signal.
• What does the ignition system consist of? Are the Ignition Parameters configured correctly?
• Are the crank & cam sync sensor signals setup/timed correctly (triggering)? Output Setup Type & Dwell Time?
• Ensure a Hall-Effect sensor is entered as "Digital Falling" or "Digital Rising", and a magnetic VR sensor as "Magnetic".
• Ensure a 5 volt crank or cam sensor isn't wired to a 12 volt reference source, and vice versa.
• Is the crank sensor air gap set within specification and is the wiring +/- polarity (VR magnetic) correct?
• Is the crank trigger's sensor air gap changing under high load (crankshaft flexing/endplay)?
• Inspect the ignition system wear items (spark plugs, wires, cap, rotor, coils, pickup modules, etc.).
• Ensure each cylinder is consistently firing using infrared temp gun, timing light and/or injector noid light.
• Fully charge the battery! Ensure the alternator is properly charging the electrical system. Check battery & cables too.
• Learn Table & injector Duty Cycle % are good troubleshooting tools. Significant new changes means something is wrong.
• Check the fuel pressure and fuel system components for leaks and restrictions (wiring, plumbing & venting).
• Use the appropriate amount of timing advance at idle. Stock cam - 20°, performance cam - 25°, radical cam - 30°.
• Are throttle blades adjusted to achieve an IAC Position of 5% at hot idle? TPS Autoset performed?
• Ensure the proper type of Advanced Idle Control is selected in Idle Settings. "Slow" may provide the best idle quality.
• If exhaust condensation is thermally shocking the WBO2 sensor, move sensor probe out of direct exhaust stream (LINK).
• Ensure there are no exhaust leaks upstream of the wideband O2 sensor(s) to prevent a false lean condition.
• Ensure sufficient length of exhaust piping beyond WBO2 sensor(s) to prevent a false lean condition at idle & low RPM.
• Any problem that prevents combustion, causes a false lean condition (misfiring, spark blowout, etc.).
• Leaded racing fuel will greatly decrease a wideband O2 sensor's longevity to within 50 hours. (Normally 500 hours.)
• Is the Bosch wideband O2 sensor malfunctioning only under boost? NTK WBO2 sensor is better for boost.
• Ensure you're using the latest EFI software & ECU firmware (LINK); it has "Oxygen Sensor Control Updates" (LINK).
• Low battery voltage will cause the wideband O2 sensor's initial heating cycle to malfunction (LINK).
• Ensure there are no vacuum leaks at throttle body and intake manifold. Some use a steel plate with two gaskets.
• If not using an electronic Transmission or Drive-By-Wire, those ICFs must be removed from the Global File Toolbar.
• Don't change naturally aspirated base calibrations to forced induction MAP sensor; Fuel Table (lb/hr) will be dead lean.
• Test the MAP sensor and its vacuum/boost hose for leaks, with a Mityvac vacuum/pressure pump.
• Upgrading to V2 software requires immediate attention: Fuel Prime %, Inductive Delay & AE vs TPS/MAP RoC Blanking.
• Diagnose all sensor values on Data Monitor for legitimacy, and retrieve any sensor codes if applicable.
• Review datalog of driveability incident. Scrutinize air/fuel ratio and timing advance. (LINK, pages 4-10)
• General engine maintenance (air & fuel filters, plug gaps, valvetrain integrity/adjustment, exhaust smoking, etc.).