the ECM does not cut the voltage to the EGRC solenoid between engine rpm 2000-4000 to allow vacuum from the throttle body to pass through the solenoid to allow the EGR to operate as it should. Exhaust temp sensor changed. Intake, throttle body, EGR tube all cleaned. MAF changed. ECM changed. Suspect coolant sensor sending bad signal to ECM. Need to fix for CAL smog. Ideas?

Any check engine codes?

If so, have you consulted the FSM for guidance on how to troubleshoot this? (You can look things up by code)

If you don't have the FSM, click the link in my signature for a free download.

Thanks but I've been using the FSM for years, thanks to Maxima.org. I use a scan tool that reads and shows all measured parameters. No codes just the EGR will not complete its test but functions properly during the solenoid bypass test. I believe the ECM is receiving a bad signal from some sensor and does not "cut" the voltage to the EGRC solenoid between 2000-4000 rpm. All components passed separate tests per the FSM.