codes PO171 and PO401 Help please

Carl333

Member
Newbie here. Read and read for hours here today.

Protege 1999 1.6 stock 70,000 miles Symptoms- Exhibiting poor acceleration, stuttering on the get go, doesn't seem to take its gas, choking. Does not stall and idles pretty smoothly.

Check engine light (for 2 years) on and the codes read as follows as of today:

PO171- bank one system too lean
PO401- EGR Flow Insufficient Dectected

This is what I have done so far.

PO401- Trying to reslove the PO401 problem, I removed the EGR and found that the valve was jammed in the closed position. After spraying several times with cleaners and manually openning and closing the valve, I finally freed it and is opening and closing freely without much resistance. Reinstalled. Above symptom is the same.

PO171- MAF Mass Airflow Sensor removed and sprayed for 10 seconds with contact cleaner. It didn't clean well. I still see some dirt but didn't want to touch the 2 wires in fear of breaking them.

Changed plugs 20,000 miles ago and looked at one plug and clean as a whistle.

Checked hoses for vacumn leaks and none that I can see.

Going into the garage to test fuel pressure, maybe change fuel filter. Perhaps change o2 sensor 1st one before converter

1- Am I on the right track?
2- Did I miss anything?
3- What is a watergate actuator and how do I test if necessary?

Thank you for your responses.
 

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