AEM Infinity Supported Applications - Universal V8 Engine - Manual (Page 35)

Universal 8 35
© 2014 AEM Performance Electronics
SYNCING IGNITION TIMING
Syncing the ignition timing ensures that the indicated ignition timing in the software matches the actual
ignition timing on the engine when checked with a timing light. Although the previous setup instructions
may have been closely followed when configuring the cam and crank inputs, it should still be considered
mandatory that the ignition timing be correctly synced before attempting to start and run the engine.
1. Unplug all fuel injectors or disable fuel pump to ensure that no fuel can be injected during cranking.
2. Open the Setup Wizard and select the Ignition Sync wizard.
3. Under Ignition Timing, check the lock ignition timing option and set the value to an ignition timing
amount that can be easily verified (0° TDC, 10° BTDC, etc.) with a timing light. Locking the ignition
timing ignores the ignition map and any other ignition trims and sets the timing to a fixed value.
4. Crank the engine and check the ignition timing using a timing light to verify that the timing at the
crankshaft matches the locked ignition timing value. **NOTE** The channel “Sync State” must go
from 0 to 1 before the ECU will fire coils or injectors.
5. If there is a deviation between the locked timing value and the actual ignition timing observed with the
timing light, use the Sync Adjustment advance/retard buttons to adjust the timing until it matches the
locked timing value. As the Sync Adjustment advance/retard buttons are used, the timing observed on
the crankshaft will change while the locked timing value will remain the same.
6. After the ignition timing has been correctly synced, uncheck the lock ignition timing option. This puts
the ignition map and any other ignition trims into effect.
7. Plug in all fuel injectors, re-enable fuel pump, and attempt to start engine if all other Setup Wizard
options have been configured.
8. Once engine is running, verify ignition timing sync by repeating steps 2–6.
TECH TIP: IGNITION PHASING, INJECTOR PHASING, AND DISTRIBUTORS
The AEM Infinity ECU bases both the ignition and injector phasing start points off of the sync event
where the ECU recognizes where the engine cycle starts/stops. In a standard distributed ignition V8
application, the ECU triggers its single coil output 8 times per engine cycle. These ignition events occur
every 90° of crank rotation. The terminals on the distributor cap are physically 45° apart which translates
into 90° of crank rotation.
The ignition firing events can be offset 90° by adjusting the CamSyncAdjustment value (in crank teeth)
and each time its offset the ignition timing will appear to be exactly the same as it was before because
the 90° of crank rotation between distributor terminals “masks” any change. While changing the
CamSyncAdjustment value to offset the ignition phasing by 90° will show no change in ignition timing,
the injection events will however be offset by the same amount thereby changing when and where in the
engine cycle that fuel is being injected.
Typically, the ignition and injection events occur roughly 360° apart with both events occurring when the
piston for any one cylinder is near TDC; TDC compression for ignition and TDC exhaust for injection.
Proper injector phasing can be easily verified by checking the injection event for cylinder #1 with a timing
light. Place the timing lights inductive clamp around one wire of the #1 fuel injector and first check the
injection event against the crank. Pointing the timing light at the crank should indicate that the injector is
firing near TDC. To check that the injection event is occurring on the correct stroke, point the timing light
at the window in the distributor cap used to check rotor phasing. The injection event should occur 180
rotor degrees (360 crank degrees) after the ignition event thus the back side of the rotor will be
illuminated by the timing light when injector phasing is correct.