TBH, if less EGR gas is entering the intake than is specified (demanded) by the ECU, you will get an 001025 - EGR System P0401 - 002 - Insufficient Flow code. It is measured by the drop in the the airflow meter reading that happens when the EGR allows unmetered exhaust gas into the intake and corroborated by the O2 sensor in the pre-catalyst on 06-on models which looks for a small enrichment.
This is continually monitored by the ECU and the EGR valve position modulated to keep it within tolerance. I suspect the restriction is not adequate to reduce it enough to trigger.
You should get better economy if anything and cleaner intake, but it may be noisier coming off the overrun as the EGR's richer mixture makes for a quieter combustion.
|