Mechanical Inspection: Compression
Check engine mechanical condition with a compression gauge, vacuum gauge, or an engine analyzer. If compression gauge is used, see COMPRESSION SPECIFICATIONS . If vacuum gauge is used, check for low or unstable vacuum condition. If engine analyzer is used, see manufacturer's manual for specific instructions.
WARNING:
DO NOT
use ignition switch during compression tests on fuel injected vehicles. Use a remote starter switch to crank engine. Fuel injectors on many models are triggered by ignition switch during cranking mode, which can create a fire hazard or contaminate the engine's oiling system.