1997 4.0 ohv with rich codes (both banks) ???

[Rangerdanger2000]

Good Evening fellow enthusiasts! Still trying to get the kinks out of my 1997 Ranger xlt so far have replaced mass air flow sensor, performed tune up (autolite plugs and duralast wires) both EGR tubes and valve have been replaced and all vacuum hoses checked over. now check engine light is on with codes P0172 and P0175. Only diffence in performance I notice is when I first start driving there is a lot of smoke exiting tailpipe then it starts to go away when warmed up other than that fuel mileage seems decent and idle is smooth. Where should I start?

 

[Rangerdanger2000]

anyone??

 

[RonD]

Check the Fuel Pressure Regulator(FPR)
It should be behind alternator on lower intake
It is at the end of the fuel rail and has Return Fuel line attached and a smaller Vacuum hose

You need to check that vacuum hose for gasoline, replace FPR if gasoline is found
This is more likely if BOTH banks see Rich codes


Leaking injector should only effect 1 bank


Rich code doesn't mean engine is actually running Rich
Same as Lean code doesn't mean engine is running Lean

These codes tells you that the computer's calculated open time for each injector is incorrect
After computers air/fuel mix is burned in the engine computer gets feedback from the Oxygen sensors(O2s)
Too little oxygen is Rich mix, too much oxygen is Lean mix

So computer adjusts the injector Open Time to get O2 sensors reading correct oxygen levels in exhaust
If you get Rich codes on both banks then computer had to reduce the open time for the injectors on both banks of the engine
So engine is not running Rich the computer is closing injector sooner, the code are to let you know there is a problem.

Partial blocked exhaust can cause Rich codes, and if you have a single exhaust, then Rich on both banks as well.

Partially blocked exhaust should cause problems at higher RPMs highway speeds and a lack of power
But lower speeds or idle would be fine