Hi there, new to the forum and the Ranger family.

I recently got a 2005 Ranger 4.0L SOHC 4x4 5 spd manual transmission with only 194000km on it and honestly I love the look and feel of it besides when it first starts up.

When it first starts up it goes through the typical idle RPMS starts up around 1500rpm drops to 1000rpm for a bit. But then when it goes to drop to around (650-750rpm from reading other topics) it goes into a very rough surging dropping to 500rpm then jumps to about 1200-1500rpm. It jumps up and down for about 30 seconds then settles at around 900-1000 rpm and will slowly walk down to around 750rpm once it’s good and warm. Also if I try to drive it during those ~30sec of surging I have little to no power/ability to raise the RPM by opening the throttle.

Also when I first got the vehicle the guy had the EGR system disconnected and “bypassed” so I replaced the valve, the solenoid and the DPFE sensor immediately.

Here’s the codes I’m getting and what I’ve replaced/looked for already:

P0446: evaporative emission system vent control circuit
P0135: o2 sensor heater circuit bank 1 sensor 1
P0141: o2 sensor heater circuit bank 1 sensor 2
P0155: O2 sensor heater circuit bank 2 sensor 1
P0161: o2 sensor heater circuit bank 2 sensor 2
P2197: o2 sensor signal biased/stuck lean bank 2 sensor 1
P2195: o2 sensor signal biased/stuck lean bank 1 sensor 1
P0403: Exhaust gas recirculation control circuit

I’ve also taken the PCV elbow off and inspected it didn’t find a crack and watched it during startup it didn’t collapse. I’ve disconnected the IACV and the engine immediately shut down. I’ve used my propane torch to spray propane around all the vacuum lines I can think of and no rev’s seem to occur so I’m less inclined to think a vacuum leak?

For some additional info for someone who might try to help me out On my code reader live data I’m getting the following readings:
MAF: 3.87g/s (warmed up idle)
O2 sensor (B1-S1): 0.430V
STFT B1-S1: ~15%
O2 sensor (B1-S2): 0.010V
STFT B1-S2: 99%
O2 sensor (B2-S1): 0.005V
STFT B2 -S1: ~15%
O2 sensor (B2-S2): 0.005V
STFT B2-S2: 99%
Wondering about your folks thoughts on what I should do next to solve either the surging or the O2 sensor codes.

Replace the low voltage sensors or look for a short somewhere?

Clean/replace the MAF sensor?

Compression test on all cylinders?

Like I said love the truck, love the highway mileage (in town seems to suck, another symptom?) just would like to try and get a handle on the repairs before it’s -25 to -40 Celsius up here.

thanks for any insight/help in advance

 

Rough idle always gets the advice to "clean your MAF sensor". Some electric cleaner sprays include lube so use a dedicated MAF spray.
Your O2 sensors are well beyond their expected life. The good news is that they are inexpensive (going by online pricing I've seen). The upstream ones always go first.
I cannot sight translate O2 sensor voltages but numbers like, "99%", makes me think your downstream sensors are at an extreme.

With a light foot (absolutely necessary with the 4.0l SOHC) I top 20 mpg on the highway WITH THE 91 gas. What are you seeing?

 

Hey

Yeah I’m probably gonna replace the O2 sensors next at least to hopefully rule out them being worn out, the guy I bought the truck from said he did a new coil pack not long ago and I double checked the wiring sequence as well.

I’m getting basically the same mileage as you with regular gas but that’s 3hrs straight hwy on cruise. Seems like I’m getting half that just starting it up and driving 3km twice a day in town though (definitely a little heavier on the foot with the more stopping and starting)

 

Okay so I still have the same issues of a rough/Hunting idle on start up (happens mostly when cold but does occur again if I shut off vehicle and start up again anything more than about 5min of being off)

all the same codes after changing all 4 O2 sensors and the MAP sensor and the spark plugs.

This morning was -30*C and it had a hell of a time once started very low RPM and extremely black smoke coming out the exhaust (see deposits in pictures on snow) (it normally has darker exhaust while in the “hunting phase 500-1500 RPM swings” and lightens as the rpm’s stablize)

after 2 min of it running like crap I shut it off and started it back up, moved it 5’ forward and had no more deposits/black smoke for the remainder of it idling.

2 start ups after replacing everything is when I got all my codes back so I’m guessing there is a disconnect between the computer and the O2 sensors at least. Anyone trouble shoot/find a typical place for the wires between the O2 sensors and the PCM to go bad/ what fuse am I looking to change for my 2005 that might be causing me to get no reading from them?

I really like the truck and looking to fix it, and would rather know sooner than later if I’m looking for a new engine to swap in haha

 

Hi everyone that might come across this in the future.

TLDR: check Engine Fuse box #41 15A

After changing basically everything that runs through that fuse I checked it, and it was blown. Monitoring now to see if it blows again to find a short however since it’s been changed all issues have been resolved.

Things that run through that fuse on the 04-06 rangers:
HEGO sensors, EVAP Canister vent valve, EGR Stepper motor, Transmission.

so if you’re throwing a combo of those codes check the fuse. And go from there.

 

+1 ^^^^

Also powers the transmission solenoids if you have an automatic trans

Common reason for this Engine Bay fuse to blow on any year(different fuse #s but always 15amp) is O2 sensor wire harness gets too close to exhaust pipe or manifold and melts, causing a short