PO171 and PO401 readings 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.
 
You should post this here. Almost everyone in the Protege5 forum has the 2.0L motor.

Running lean is not very good for an engine. Doing it for two years? (headshake
 
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