Exhaust System Backpressure

Check exhaust system using vacuum gauge or pressure gauge. Remove O2 sensor or air injection check valve (if equipped). See Fig 1 & 2. Connect a 1-10 psi pressure gauge, and run engine at 2500 RPM. If exhaust system backpressure is greater than 1 3/4 - 2 psi (.12-.14 kg/cm² ), exhaust system or catalytic converter is plugged.
If using a vacuum gauge, connect vacuum gauge hose to intake manifold vacuum port and start engine. Observe vacuum gauge. Open throttle part way and hold steady. If vacuum slowly drops after stabilizing, check exhaust system for restrictions.

Fig 1: Electronic Ctrl Sys (Swift DOHC Shown; Samurai is Similar)

Courtesy of SUZUKI OF AMERICA CORP.

Fig 2: Electronic Ctrl Sys (Swift SOHC Shown; Samurai is Similar)

Courtesy of SUZUKI OF AMERICA CORP.