Load Sensor

1. Connect an adjustable timing light to cylinder No. 1.
2. Start engine, then check ignition advance with engine running at 4000 RPM.
3. Correct ignition advance is 37--43°. If advance cannot be obtained, apply approximately 14 inches of vacuum to ECU vacuum hose with a vacuum pump. If ignition now advances, check vacuum hose between ECU and intake manifold for leaks. If ignition does not advance, replace ECU.
4. Disconnect vacuum hose from intake manifold, then recheck ignition advance.
5. Ignition advance should now be 17--23°.