Downstream O2 Sensors cut no CEL?

[Jedijoy13]

Hey Everyone,

2014 6.2L with Shelby supercharger kit. 148k

I bought this truck last year and it's time for emissions. There is no check engine light, so I took it in and the emissions place said it failed with all the gases high. I checked the codes and realized that the O2 heaters on the downstream were not working. I pulled one of the spark plugs and it turns out it was gapped to .04, so I called Shelby and they told me it should be .028 to .029. Fixed that for all of the plugs last month. Onto why the O2 wasn't working. Crawled under the car yesterday and found both downstream sensors cut. The sensors were stuck, so I ran out of time before being able to get them out yesterday. I plan to put new sensors back in next weekend, but am worried that maybe they're disabled somehow? Main question is I thought a CEL would show up if the sensors were removed? Anyone remove the downstream sensors and not get a code? Any advice would be appreciated.

 

[CoronaRaptor]

I would bet that the tune has shut them off, just a thought. Do you have forscan, you could check on there I think. I'm sure Shelby never did that, but you never know what's been done by the previous owner(s).

 

[MTF]

Shelby uses a proprietary Tune built by Whipple and the rear O2s are not turned off by default.
Plus, if you have the stock exhaust manifolds there wouldn't be any need to disable the rear O2s.
Now, if you have the stock manifolds, it could be someone installed those cheap Hi-Flow cats.
Then you need to use O2 spacers on the rear O2s or turn off the rear O2s in the Tune.

Since you are not the original owner, my guess is as good as yours as to what is going on.
It's quite possible that it's not even the original Tune any longer.

 

[Jedijoy13]

Got the new O2 sensors in over the weekend. My OBD reader is now reading voltage off them. I suppose the PO just got lucky when he cut the wires. Going to drive the truck for a week and hopefully the OBD readiness for the sensors will complete.

thanks for the suggestions, I do plan on getting FORSCAN, just haven't yet.

 

[MTF]

Got the new O2 sensors in over the weekend. My OBD reader is now reading voltage off them. I suppose the PO just got lucky when he cut the wires. Going to drive the truck for a week and hopefully the OBD readiness for the sensors will complete.

thanks for the suggestions, I do plan on getting FORSCAN, just haven't yet.

It shouldn't take a week just a drive cycle, it's usually a mix of highway and street driving for about 50 miles.
One important thing to do is three decelerations from 50-60 mph to 0 in the drive cycle.

 

[Jedijoy13]

It shouldn't take a week just a drive cycle, it's usually a mix of highway and street driving for about 50 miles.
One important thing to do is three decelerations from 50-60 mph to 0 in the drive cycle.

yeah, that's why I figured it would take a week, not sure where I can go near me where it's safe to do the 60 to 0 deceleration (I need to pull up the OBD test procedure again, but if I remember correctly, it's supposed to be without hitting the brake).

 

[MTF]

yeah, that's why I figured it would take a week, not sure where I can go near me where it's safe to do the 60 to 0 deceleration (I need to pull up the OBD test procedure again, but if I remember correctly, it's supposed to be without hitting the brake).

I've switch and/or changed values with Tunes so many Times, over 50 at least, sometimes it sets to ready after one decel, sometimes it takes two days.
And I only drive 16 miles per day with about 100+ stops (LOL) on average.
You can use the brakes a little, for what I've experienced it just needs a certain amount of seconds to do the decel test.
It says 50-60 in the book but I bet you can go slower, I've never paid attention to the speed actually.

 

[Jedijoy13]

Still not getting them to complete, and i've been driving a little extra after work. I did have a code come on - P219A. It seems to be a historic code, haven't been able to see it real-time. I had the code in the past along with the P219B and solved it by replacing the IACV. I also noticed by O2S2 does not register voltage when I have the OBD scanner connected, where O2S1 is at 1V, sometimes goes to 2V while driving. I guess that's the next component that I need to check. 02S2 is the the driver side, right? Considering how sooty the downstream O2s were, i wouldn't be surprised if one or both the upstream O2s are fouled up.

 

[MTF]

You went this far, I would replace both fronts at this point.
And double check all the wires for cuts, nicks, dry rot, burning, corrosion.
These wires are super small and sensitive because of the use of low voltage and can break anywhere along the run.

Have you pulled the three plugs at the PCM to look inside?
Also you may need to open up those plugs and look behind at the pins.
I have a post I just recently post on how to open them.

Yeah, permanent codes need a software(Tune) PCM reset.
I believe there are a few guys on here that swear they can delete permanent codes without a full PCM reset.

Usually permanent codes erase themselves when the problem is fixed and three consecutive drive cycles complete with no errors.
That's with 6-8 PCM clock hrs. of the truck being off in between drive cycles.

Have you considered calling Shelby or Whipple and getting your Tune?
If you get the SCT X4 handheld device with your Tune bundled, you can save a little money.
You would be able to adjust a few settings by yourself within the Tune like, tire pressure, tire size, timing.
Plus, Whipple would help with letting the dealer access your Tune for diagnostics.
That's if you can find a dealer willing to do that, there are authorized Whipple Ford dealers around.

 

[Jedijoy13]

Don't want to Jinx it, but the O2 monitors must have completed this morning during my drive to work. The CEL turned off when I got back in to drive home after work. Only thing i did yesterday was wiggle the iacv hoses and wiring to make sure it was secure. I'm going to try to give the smog test a go tomorrow.

I had considered getting the stock Shelby tune as a last resort. I wanted to make sure the items that were cut/not working were replaced and/or working as they should be.

I really don't think the PO messed with the tune, the truck looks really clean and was probably a highway warrior. All of the fluids were clean when I bought it. If I had to guess, I imagine they either did the spark plugs themselves or took it to a shop that didn't know any better and just threw un-gapped plugs. That probably caused a CEL and why they cut the wires. At least they used the Iridiums. Spark plug wires are either original or were replaced with the plugs.