Hello, my name s Jim . I have a 98 ranger 4x4 with the 4.0. Need to get some help with figuring out why my truck starts bucking and misfiring about every six montus. I have already replaced the maf, idle air control, oxygen sensors, plugs, plug wires and coil pack. I heard that it could be because of the catalytic converter being clogged, any ideas?

 

That definitely may have something to do with it... and welcome!

 

Hey there Jim. Are you throwing any OBD codes? Symptoms are kinda similar to what I experienced on my 94 crown vic, turned out the EGR system was jammed up. You gotta take off the TB elbow and clean out the channels in there, they get all full of carbon (dont forget to replace gaskets if you do this). And the DPFE sensor (part of the EGR system) is problematic for rangers, i've heard, but that should definitely throw some codes. I'm new to this family of trucks and engines tho, so that's just my two cents. . .get some more input before you go tearing into the EGR, it can be a headache of a job.

 

Just went and had the codes checked, I am getting 1151, 0171, 0305, and 0306

 

Ford codes - http://www.obd-codes.com/trouble_codes/ford/
generic codes - http://www.obd-codes.com/trouble_codes/

Copied from their site:

P1151 Lack of Upstream Heated Oxygen Sensor Switch - Sensor Indicates Lean - Bank No. 2 http://www.obd-codes.com/trouble_codes/ford/p1151.php
P0171 System too Lean (Bank 1) http://www.obd-codes.com/p0171
# P0305 Cylinder 5 Misfire Detected http://www.obd-codes.com/p0305
# P0306 Cylinder 6 Misfire Detected http://www.obd-codes.com/p0306

put those links in your address bar for more detailed info...seems to me like you're not getting enough fuel?

the 1151 is the main cause of concern, the misfire codes are probably just secondary to that problem. Again, copied from the link:

Technical Description

System Too Lean (Bank 1)
What does that mean?

Basically this means that an oxygen sensor in bank 1 detected a lean condition (too much oxygen in the exhaust). On V6/V8/V10 engines, Bank 1 is the side of the engine that has cylinder #1.

Note: This DTC is very similar to P0174, and in fact your vehicle may show both codes at the same time.
Symptoms

You will more than likely not notice any drivability problems, although there may be symptoms such as a lack of power, detonation (spark knock), and/or a hesitation/surge on acceleration.
Causes

A code P0171 may mean that one or more of the following has happened:

* The MAF (Mass Air Flow) Sensor is dirty or faulty. Note: The use of "oiled" air filters may cause the MAF to become dirty if the filter is over-oiled. There is also an issue with some vehicles where the MAF sensors leak the silicone potting material used to protect the circuitry.
* There could be a vacuum leak downstream of the MAF sensor.

Possible Solutions

A code P1151 may mean that one or more of the following has happened:
Electrical:

* Short to VPWR in the harness or HO2S
* Water in the harness connector
* Open/shorted HO2S circuit
* Corrosion or poor mating terminals and wiring
* Damaged HO2S
* Damaged PCM

Fuel System:

* Excessive fuel pressure
Leaking/contaminated fuel injectors
Leaking fuel pressure regulator
Low fuel pressure or running out of fuel
Vapor recovery system

Induction System:

* Air leaks after the MAF
* Vacuum Leaks

PCV system:

* Improperly seated engine oil dipstick

EGR System:

* Leaking gasket
* Stuck EGR valve
* Leaking diaphragm or EVR

Base Engine:

* Oil overfill
* Cam Timing
* Cylinder compression
* Exhaust leaks before or near the HO2S(s)


Start at the top of the list and work your way down. Hope this helps.

 

you're also getting codes for "system too lean" on both banks. Change your fuel filter?