Ck engine Light Yet Again....
Once again that elusive ck engine light is coming on.
Code # 171 & 174
Bank 1 & Bank 2 running lean codes.
I have replaced the Mass Airflow sensor, the Fuel Pressure Regulator, 2 of 3 O2 sensors, cleaned the throttle plates with cleaner and new air filter.
I know there is still the option of replacing the EGR Valve, I have gone over every vacuum line on the engine to look for leaks.
I have an OBDII reader and just keep clearing the codes.
This is on my 1997 Ranger XLT SuperCab, 4.0 with 5 Speed Auto, 111,500 miles on it, I have owned it from day 1.
The only immovability issue is when I let off the gas pedal now and then the engine will surge, try to stall, you can even see the lights go bright and dim, and then when I come to a stop she idles fine.
She has plenty of power and runs perfect above 900rpm.
I dont get the surging all the time just now and then.
I'm open for suggestions.
About a year ago I installed Bosch IR Fusion spark plugs, wondering if they are doing too good of a job ? FYI