Don't forget this could be having a bad effect on the cat converter, as it has to process all of the left over unburned fuel putrids from a poor combustion event.

 

Put the sensors in and still got a PO420 cel.

I replaced the blower fan a few weeks ago and after I put it back together it started not wanting to start. Two or three attempts sometimes and never right up like normal.

 

One thing at a time. Have a read here on the P0420 code. https://www.obd-codes.com/p0420. If both sensors output look a lot alike, it sounds like the cat converter on that bank may be laying down on the job?
Seeing as how you have now replaced Both upstream O2 sensors, what does their switching range, speed & profile look like? Would be interesting to view a new Oscilloscope plot for Both new upstream O2 sensors.

On the blower fan, I suppose you mean you replaced its motor & now its intermittent? If so, was it intermittent beforehand?
Is the replacement new, reman, salvage?
Did you test the motor before installing it?
Check the electrical connections to it. Perform some wiggle thump tests to see if you can narrow down the suspect list.

 

I'll get new readings. Yeah, probably a cat is bad.

The blower motor quit and after I replaced it the truck started acting up when I started it. I've looked and dug around everything seems to be back in place and right (had to remove the air box, coolant/washer tank, cruise control servo and some harness connectors) Checked all was back in place and nothing was missed.

 

Here's the graph.

 

The new upstream O2 sensors seem to be switching faster & the voltage range & speed is good. The after cat converter sensors seem to be suggesting not much is going on inside the converters.

On the heater fan woes, you might have the ELM & FORScan perform another scan, as that combo can query the GEM/Body controller for any pending, or set Body trouble code clues that might be able to help focus your trouble shoot. If no joy there, revisit the electrical connectors messed with & as suggested try wiggle/thump tests to see if you can induce, or clear up the intermittent run problem. Then concentrate your attention to that connector & its wiring & pins/sockets for corrosion, loose fit, poor wire crimp, or mashed/pinched/cut wire, or signs of insulation damage that might tattle on parted wire strands inside the insulation.

I forgot to ask, did you have any problems getting the old upstream O2 sensors out?
My 99 4.0L upstream O2 sensors are about ready for replacement mileage wise, so I'm thinking of including their replacement in my upcoming 90K service regimen.
Had a peak under there while changing the oil & filter a few weeks ago & it looks like the drivers side before cat O2 sensor might need a short offset socket to get it out. The firewall sensor on my 3.8L Taurus was in a like Really tight spot, that only the short offset socket in the Advance Auto "Loan-A-Tool" O2 sensor socket set, could have gotten out.
Haven't had a look at the passenger side upstream sensor yet, kinda afraid to look, might be more that I want to mess with, not having a lift, just ramps. Anyway any feedback on what you ran into & overcame might give me & anyone else contemplating this job, a heads up!!! Surprisingly though, the 94 Taurus 3.8L O2 sensors came right out, but the factory had anti-seize compound on the threads & it did its thing, so I'm hopeful the same will be so for the Ranger.

 

I went ahead and paid labor to have them done, affraid I was going to break something fighting them out (maybe me).

I guess I'm going to grab a front pipe/converter set and do them.

I get a feeling the start issue is leaky injectors. Sometimes it happens and sometimes doesn't. Getting more that it does.

 

Thoughts on the Magnaflow setup ? HM will be okay on this non California truck ?

 

I've not had to replace a cat converter, so don't have any experienced input, but maybe a member reading this that has will answer up with their experience. There was a FTE member from the old MotorWeek forum that sold cat converters, that had good inside info, but he hasn't posted in a while & ( right now I've forgotten his online name & am having no search luck), so you could PM him for his advice on a worthy aftermarket cat for consideration. If I can remember his online handle I'll post it up, or PM you with it.

 

[QUOTE= HM will be okay on this non California truck ?[/QUOTE] What is HM?

 

They list HM and OEM, from reading more the HM (heavy metal) is 49 state OBDII and the OEM is for California.

MagnaFlow's HM grade Direct-Fit catalytic converters are designed for easy, bolt-on installation and do not require cutting or welding. They feature American made stainless steel construction and a high quality flow-efficient monolithic honeycomb catalyst that is designed to provide long life and clean emissions. HM grade Direct-Fit catalytic converters are designed specifically for OBDII vehicles registered outside the state of California that have an EPA emission system. You can identify if your vehicle has an EPA emission system by checking your emission tag located under the hood, on the suspension tower or on the radiator shroud. If the emission tag does not say California anywhere on it, it is safe to assume your vehicle has an EPA emission system. Direct-Fit catalytic converters feature the necessary gaskets which takes any guesswork out of installation.

• Stainless steel construction
• Federal emissions compliant design
• Formulated for gas and diesel applications
• Seam welded close to the converter body for a strong, tight bond
• Made in the U.S.A.

 

I think I can get to everything. Sprayed some PB blaster on the seven bolts and need a 15mm deep 6 point (I need to learn to count). (All my metric stuff got stolen, so I have to buy as needed)

I'm going to look at the magnaflows tomorrow.

 

I just bought a set of deep, 6point thin wall sockets from Harbor Freight to remove lug nuts on the Taurus cast wheels & Ranger chrome wheels so they won't drag in the well. They fit tight on the nuts & have so far held up ok for that task. Quality seems good for the price point, so they might be worth a look for your job. https://www.harborfreight.com/10-pc-...ket-67873.html

 

I can't bring myself to by at Harbor Freight anymore. I have a 3/4 drive set here at work and the sockets just fall off the breaker bar. Lowes has a 6 point 15mm impact socket for 6 bucks, I'll grab that and hopefully it will fit in there.

https://www.lowes.com/pd/Kobalt-Metr...Socket/3388856

 

The back three nuts came loose by hand, the front ones at the manifolds so far aren't budging. I'll put some more penetrating oil on them and give it another shot later. I'm using 120lbs from a 30hp compressor to the impact wrench.