Running rich all the time

[savage]

ok, my truck is a 99 ranger xlt 4x4 w/manual trans, 4.0. about 3 weeks ago after an oil change, my truck started running rich all the time with the DTC's of P0135 (o2 sensor heater circuit malfunction bank 1 sensor 1), P0141 (o2 sensor htr cirkit malfunction bank 1 sensor 2), p0155 (same as above but bank 2 sensor 1), and p1132 and p1152 which are Lack of HO2S bank 1, sensor 1 switches, sensor indicates rich and same thing for 1152 but for bank 2, sensor 1 switches, sensor indicates rich. I have done all the possible troubleshooting according to my ford shop manuals and everything has tested ok. I have also looked for intake leaks but couldnt find any. I just read a few moments ago about a tsb for the upper intake gasket to the fuel rail but i couldnt get a indication of any leaks when i tested for them. All of the o2 sensors have been replaced within the last 3 years and both upper bank o2's i replaced 2 weeks ago. i am so lost, any suggestions? and as far as aftermarket mods go i have a cold air intake and cat back exhaust.

 

[KELLY88]

Sounds like something electronic. Like maybe your MAF sensor is giving off bad readings.

 

[savage]

checked it and it is functioning like it should. and i also forgot to mention that the truck surges a little bit at spds between 10 and 45 and it is running rich enough that fuel is geting into the crankcase.

 

[KELLY88]

Surging would say that you have a vacuum leak somewhere.

 

[savage]

didnt find any of those either...

 

[Big Jim M]

Didja squirt a bunch of carb cleaner around the vac places? That is the way to find vac leaks.. Either will also do the trick.
Big JIm

 

[savage]

yeah i did, and i used brake cleaner since it doesnt leave a residue. didnt find anything.

 

[almostclueless]

Take it to a good ford dealership for a diagnostic.

 

[Yellowsplash]

hmm....vacuum leaks usually pop a lean code rather than a rich. Have you checked the fuel pressure? Maybe the vacuum line running to the fuel pressure regulator?

btw, if your getting a heater circuit malfunction, the O2 is bad. Did you get a universal O2 sensor and splice it in? Spend the extra money to get an OE Type direct fit connector. This solves the problems that could arise from bad wiring...

Ohh...and did you clean the MAF with CRC's MAF cleaner?

 

[90rangersuper]

i had a nightmare time this winter with my ranger running rich, all sorts of codes came up, mine is a 90 so some sh*t might of changed but for me in the end it was the coolent temp sensor which fixed my issue running rich, i replaced the HEGO,TPS,IAC, plugs, wires and fuel filter and cleaned the MAF before changing out that sensor after i changed that sensor she ran like a champ, hope this helps and good luck

 

[Yellowsplash]

yea, the coolant temp sensor could cause the truck to stay locked in open loop and run rich. The throttle positioning sensor could also cause the ecu to think the truck is under more load and send more fuel, thus causing the surges/bucking.

 

[savage]

replaced the coolant temp sensor, though there is a sender for it but cant find it in the wiring diagrams book and i did replace the throttle position sensor. I did a test however that said the pcm was bad. still looking into this.

 

[savage]

never mind about the sender. i had a brain fart, its for the gauge, not the sensor.

 

[TonyG1989]

Take it to a good ford dealership for a diagnostic.

replaced the coolant temp sensor, though there is a sender for it but cant find it in the wiring diagrams book and i did replace the throttle position sensor. I did a test however that said the pcm was bad. still looking into this.

Im right here with you, ive done everything, still rich. Im on a computer purchase soon but tomorrow ill try a coil replacement.

 

[holyford86]

if the exhaust was welded on, it may have burned out the section of the EEC that controls the O2 sensors, I've seen it more than once.