EGR Valve
- Ensure all vacuum hoses are correctly routed and securely attached. Replace any crimped or broken hoses. Ensure there is less than one in. Hg vacuum to EGR valve at idle with engine at normal operating temperature.
- Remove and plug vacuum hose at EGR valve. Connect scan tool to DLC. Access DPFEGR and RPM PIDs. Place transmission in Neutral. Start and operate engine at idle. Note idle speed. Using a hand-held vacuum pump, slowly apply 8-10 in. Hg vacuum to EGR valve for 10 seconds. If engine starts to stall, increase RPM to maintain 1000 RPM. Look for following:
- EGR valve starts opening at about 1.6 in. Hg vacuum indicated by increasing DPFEGR PID voltage.
- DPFEGR PID voltage reading increasing until EGR valve is fully open. DPFEGR PID voltage reading should be 2.5 volts minimum with full vacuum applied.
- DPFEGR PID voltage reading steady when vacuum is held. If DPFEGR PID voltage reading drops within a few seconds, EGR valve or vacuum source could be leaking.
If DPFEGR PID voltage reading indicates EGR valve is operating properly, restore vehicle to original condition. If DPFEGR PID voltage reading indicates EGR valve is not operating properly, remove EGR valve and check for signs of unusual wear, contamination, carbon deposits, binding, leaking diaphragm and other damage. If EGR valve is okay, look for an obstructed EGR port in intake manifold or plugged orifice tube. For additional EGR system testing, refer to appropriate SELF-DIAGNOSTICS article.