1996 5.0 Oxygen Sensors?

[LVExp]

I just put a bunch of work into my old 1996 Explorer 5.0 and am getting P1072 and P1075 codes. I've checked the MAF, air filter, Vacuum leaks etc and everything appears to be fine. Then looking at the scan data I noticed all 4 brand new O2 sensors are almost mirroring each other and this made me remember I had questions when ordering the O2 sensors.

parts.ford.com only lists one Oxygen sensor for my vehicle and that's DY1401 and is described as "downstream".

Rock Auto lists all sorts of things from multiple parts for all four positions, one part number for 3 of 4 position, one part number for the 4th position. And for Bosch they list one for "Downstream or Upstream Left" and one for "Upstream Right".

Autozone lists Bosch 15717 as Upstream "Narrowband. "RIGHT", exact fit or "LEFT"" and 15719 as Upstream "Notes: Actual OE Part, Narrowband. "RIGHT". Alternative Fit 1" with no Bosh listed as Downstream.

What I purchased and installed were 2 x Bosch 15717 for both Upstream and 2 x 15716 for both Downstream.

Was this correct? If not what are the correct parts numbers and combination?

 

[410Fortune]

The different part numbers are basically the length of the wires and the shape of the connector locking pins
They are basically all the same 02 sensor otherwise

The codes you have indicate way too much fuel being delivered both banks
What work did you do to the truck?
I will look up those part numbers but those are not necessarily 02 sensor codes

Copy paste from Google search p1072

• A dirty mass air flow sensor overstating the amount of air entering the engine which may cause excessive fuel delivery
• A bad oxygen sensor
• A leaking fuel injector allowing too much fuel to enter the combustion chamber
• A faulty fuel regulator, which may not be regulating the pressure of the going to the engine as it should
• A vacuum leak
• A possible fault in the coolant system such as a stuck thermostat or bad coolant temperature sensor
• Worn spark plugs

 

[Mbrooks420]

Pulling the plugs for a look would likely tell if an injector is sticking.

 

[410Fortune]

Sounds
Like an injector is dumping fuel that is for sure, like stuck open
Or you have an intake leak or the mass air sensor is fubar

 

[LVExp]

The different part numbers are basically the length of the wires and the shape of the connector locking pins
They are basically all the same 02 sensor otherwise

The codes you have indicate way too much fuel being delivered both banks
What work did you do to the truck?
I will look up those part numbers but those are not necessarily 02 sensor codes

Copy paste from Google search p1072

• A dirty mass air flow sensor overstating the amount of air entering the engine which may cause excessive fuel delivery
• A bad oxygen sensor
• A leaking fuel injector allowing too much fuel to enter the combustion chamber
• A faulty fuel regulator, which may not be regulating the pressure of the going to the engine as it should
• A vacuum leak
• A possible fault in the coolant system such as a stuck thermostat or bad coolant temperature sensor
• Worn spark plugs

I replaced the drivers side catalytic converter, passenger side exhaust manifold, O2 sensors, and muffler back.

I cleaned the MAF for a second time, pulled most of the spark plugs and they were dark (probably from this running rich issue) but not extremely black or dirty. I will recheck for a vacuum leak and check the fuel pressure.

 

[Fix4Dirt]

can you take a look at the values for the maf? i know you cleaned it, but they can go bad too...

 

[LVExp]

can you take a look at the values for the maf? i know you cleaned it, but they can go bad too...

At ~900 RPM idle the MAF is between .85 and .92 volts

 

[LVExp]

Update: Fuel pressure when running is 35-40 PSI, however when the engine is shut off it drops to 8 PSI in 18 seconds. Following the FPR testing procedures found on All Data I found fuel in the FPR vacuum line and am replacing the FPR tonight.

Would the FPR being bad cause P1072 & P1075?

 

[Fix4Dirt]

i would assume so as p1072/5 is iirc for rich banks 1/2 so i assume if its not properly regulated it would cause a rich code and about the MAF value i realized you have a v8 and i have a sohc, so im not actually sure what it should be... hopefully someone else knows!

edit: see post 2 by 410fortune

 

[LVExp]

It was the FPR!!!

Following the procedures to test the fuel pressure regulator i found the FPR was not holding pressure and there was fuel in the vacuum line. Immediately on first start after replacing the FPR the engine ran like it's supposed to.

Got P1072 and P1075, TEST your Fuel Pressure Regulator.

Thanks to everyone for there help

 

[Fix4Dirt]

yay! glad to hear it all worked!