tommyboy180

I'm trying to get Torque setup and I started monitoring Bank1 and Bank2 O2 sensors. Bank 1x2 gives me a reading but it's slow and stays high while Bank 2x2 has a lot of variation.

So my first though is a plugged cat, but I have no idea how to diagnose that. I'm wondering if that means a sensor is acting up? No idea. I'm hoping someone that knows what it should look like can give some pointers. Thanks!

Note, in the 3 screenshots, I'm either at idle sitting still or giving it very little gas. So in the case of idle Bank2x2 was reporting voltage at 0.1~0.2 ranges.

techrep

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tommyboy180

2008 5.4L 3v.

F150Torqued

You have your Torque Pro screens set up right, although I prefer the '+' / '-' digital scales showing STFT and LTFT in -30 to +30 %. >25 LTFT & 10 STFT will trip a code.

As for O2's, your upstream look fine for closed loop operation. I would simply comment there is insufficient information to be conclusive on downstream. The CATs must be up to operating temperature to actually 'start working'. The best environment under which to monitor them is light cruise around urban freeway speed ( 40 MPH give or take 10). If the cats are storing enough oxygen to release and burn off excess hydrocarbons from short richer fuel trim moments, the trace should bobble along +0.5 to +0.7 mostly. some mild to moderate acceleration for 15-20 seconds will send downstream O2's to +.8 or +.9 until things stabilize again. Periods of coast will send downstream O2's to flat-line 0.1 v.

Your O2 sensor 'stuck rich' (flat line at +.8 or .9) can be a defect in wiring connections or defective O2 sensor. Given you are having a flakey problem with 'EOT' reading, I might suggest (disconnecting battery) an using some good spray contact cleaner on PCM Plugs - plug / unplug / replug them several time trying to insure all pins make good contact. Just A Thought.

tommyboy180

Thanks for the reply! You're always really helpful.


Not pictured is my cruising at highway speeds. Bank 1 downstream looks the same at highway speed, low speed, idle, etc. It's stuck in that 0.6~0.7 range. It fluctuates, but only slightly. Even coasting with no acceleration, it stays in that same range.


Will do. I'll take a look for that EOT sensor too. So, considering that I properly reconnect PCM plugs and I'm still having the Bank 1 downstream problem, would it be advisable to replace that sensor?

F150Torqued

If it stays the same during deceleration - (Upstream O2 should go to flat line at bottom ~ 0.1 v --- flooded with unburned oxygen), and there would be NO explination for downstream to remain at same voltage. Given that All four O2's are the same, - and downstream are easiest to access, I would not consider it throwing parts to try another O2 there. I do Still find it a couple of things a little suspicious. The PCM provides a 'reference' voltage to the O2 sensors. The Sensor pulls that voltage to ground in presence of oxygen. It is a little odd (but conceivable) that it would fail AT A SPECIFIC voltage level instead of solid HI or Lo. ??? Also, Why do you not have a P0420 (Which occurs as a result of Switching Ratio between upstream and downstream O2's falling outside factory set limits --- ie: 60 - 75 %, depending on exhaust configuration, during Cat Efficiency tests.) Bunch of latest test results can be seen VIA a Mode 06 "Test Results" report, including cat midbed temperature.

Also, I have posted a Torque dashboard screen to see ALL of the OBDII Monitor routines as they 'complete'. It would be interesting to know if the CAT Monitor completes --- EVER. https://www.f150forum.com/f4/how-use...7/#post5992223

Eric Kleven

been playing with similar screens, do this:

• Add to that screen a similar graph for commanded AFR, and maybe engine load %
• Fuel trims aren't going to be helpful for what you're after, maybe replace them with cat temps (which would be helpful)
• From a highway-speed cruise, let off the gas and hit the O/D Off button to put the trans into Drive
  • On my truck, this causes the AFR to go to about 14.8:1 (lean) and both front & rear cat O2 graphs drop to the bottom and stay there until I put some gas on it again. Cat temps also start heading downward rapidly.
  • This could maybe be used frequently as a tool to clear out mildly carboned-up cats.

Let us know how that turns out.