Core EFI V4 Manual

Work top to bottom. The ticks stay on this phone. Do not add fuel until RPM and a locked 10° timing light on cylinder 1 are real.

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On the bench, key-on, engine off

TunerStudio connectsVCP enumerates. Firmware version matches the ini. Save a blank .msq.
Battery voltage reads 12–14 VSensed on M4 after the main relay clicks. If TunerStudio shows 0 V, M4 or the relay is wrong.
Main relay latches on key-onL4 wakes the ECU, E4 grounds the coil, M4 goes live. Relay stays on until key-off plus a short write delay.
Both 5 V rails are 4.9–5.1 VC2 (MAP) and B1 (TPS) to sensor ground. A shorted rail is a sensor or a crushed wire.
CLT, IAT, TPS, MAP look saneCLT ≈ ambient, IAT ≈ ambient, TPS closed 0.4–0.8 V, MAP ≈ baro with the hose off.
Output test: injectors, coils, pump, fan4-cyl: C4–B3 and K4–K1. 6-cyl: K1 / J3 / J4 into the 3-channel injector driver, coils on K4–K2. 8-cyl: J4 / J3 into the injector driver, K4–K1 coils. Pump on D2.
If DBW: pedal moves the blade, spring-shut worksUSB unplug must drop the throttle closed. Skip this on a cable throttle.

RPM 150–300 while crankingNo RPM = trigger, not tune. Composite logger before anything else. Swap VR polarity on A4 / A3 once.
Full sync (cam if sequential)Batch / wasted spark run on crank only. Sequential COP needs F4 as cam, not VSS.
Timing light at a locked 10° on cyl 1Set fixed timing. If the light is 180° off, fix offset — do not add fuel.

Re-enable injectors, prime the railPump primes on key-on. Crack a union if the rail is dry. No start spray down the intake.
It catches, AFR is 11–14, oil pressure is upIf it fires and dies, add cranking fuel, not running VE. Kill it if oil pressure is zero after 3 seconds.
Cooling fan comes onSet a low on-temp for the first run.
Save a log and the .msqFirst idle log plus the project file. This is the only baseline you will ever have.