2000 Nissan Xterra ROUGH ACCELERATION

BASIC DIAGNOSTIC PROCEDURES -2000 Nissan Xterra SE
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Exhaust System Backpressure
Visually inspect exhaust system for dents, damage and leaks. Repair or replace as necessary. Exhaust system can be checked using a vacuum or pressure gauge.
If using a vacuum gauge, connect vacuum gauge hose to intake manifold vacuum port. Start engine. Observe vacuum gauge. Open throttle part way and hold steady. If vacuum gauge reading slowly drops after stabilizing, check exhaust system for a restriction.
If using a pressure gauge, remove front oxygen sensor. Connect a 0-5 psi pressure gauge. Run engine at 2500 RPM. If exhaust system backpressure is greater than 2 psi, exhaust system or catalytic converter is plugged. Repair or replace as necessary.

9/13/2008
Test the fuel pressure while your at it.
https://www.2carpros.com/car_repair_video/test_fuel_injection_pressure.htm
Go here and checkout our video.

Sometimes a clogged exhaust can vary in the circumstances.
To remove the fuel you can either use the fuel pump to pump it out (remove fuel hose from fuel rail and attach a hose to a collecting tank, loop the fuel pump relay to get it running with ignition switch on)

Or drain it from the fuel tank via the drain plug (some models are not equipped with drain plugs)

If engine is equipped with EGR system I would suggest disconnecting the EGR valve vacumn hose to test.