Replaced O2 sensors still running poorly

[Herb2017]

All,

I have a 2006 Expedition 5.4. It was running very poorly, not responsive to acceleration, etc. Engine light came on, codes for sensor 1 on both bank 1 and 2. I replaced bank 2, sensor 1 but had a wiring problem issue on bank 1, sensor 1 and ended up taking it in and having a local place rewire it. I posted about it here.

After the rewire, it ran better than it had in months for about 2 days. On the 3rd day it basically reverted to the same poor running. At this point it's very difficult to even drive. It has the same behavior in that I need to really gun it to get accelerating and then level off when up to speed. But if I just 'normally' press the peddle to slowly gain speed, it will bog down and eventually the exhaust pipes will vibrate and shake making a loud noise.

THE CHECK ENGINE LIGHT IS NOT ON!!!! I put the cheap ODB2 unit I have on it and it doesn't detect any codes either. I'm not sure how it can be running so poorly and not have a check engine light on. It's been 3 days of this poor running without a code.

Does anyone have any idea of why the the check engine light isn't on? I can believe that the cheap ODB2 unit I have may not be able to do a professional job but does the lack of light say anything about the computer itself, not functioning properly, needs reset, anything? Does the described behavior suggest anything obvious? Fuel line, fuel filter comes to mind but it is the same behavior I had prior to getting the disconnected O2 sensor wiring fixed.

I'd like to get some opinions prior to taking it back in to the place that did the rewire since it's the first time I've used them.

Any guidance is appreciated.

Thanks in advance,

HB

 

[docraymund]

You can inspect all the plugs for fouling. You need to check fuel pressure. The Forscan app for windows is a better free alternative. Connect it to your laptop via a bluetooth obd reader.

 

[Herb2017]

Thanks @docraymund .. I will look into the Forscan app for Windows.

I'm still confused at no engine light.

 

[stamp11127]

Two reasons for not having a cel on:

1) The sensor inputs to the pcm are all within spec for each sensor

2) Engine hasn`the run long enough for the pcm to store a code

Since you have tried driving it, focus on #1 above. So the question now is, what isn't monitored by the pcm?

Exhaust (read the temps of the cats, clogged temps are high)
Fuel pressure
Injectors
Spark plug gap
Idle air control
Specific vacuum lines
And probably a bunch more

 

[Habbibie]

OP I experienced the same issue before, however I replaced all 4 sensors and cats and it hauled ass the first 2 days then it went back to retard mode... after chasing my tail trying to figure it out I randomly decided to reset the pcm by unplugging the negative terminal and keeping my headlights on for about an hour, then i started it up and it drove better for 2 more days until the pcm learned all new input values and corrected itself to regain optimal performance.. 4 days after doing the reset it was hauling ass again but this time it stayed that way... it's been 4 months and no hick-ups since.....

 

[Herb2017]

Thank you @stamp11127...

To confirm, you are saying that this list:

Exhaust (read the temps of the cats, clogged temps are high)
Fuel pressure
Injectors
Spark plug gap
Idle air control
Specific vacuum lines

would be things that are not monitored by PCM? Meaning issues with these would not code?

@Habbibie - Thank you, that is great information. I will try what you did and report back.. I appreciate the suggestion..

HB

 

[stamp11127]

An issue with any on the list will not generate a code specific to the problem. However over time it may generate a general code for the problem. For example a misfire code doesn't tell you what is causing the code, only that there is a misfire on a specific cylinder.

 

[Wegner44]

Have you tried thoroughly cleaning the throttle body? I have had a rough running issue twice and a good cleaning took care of it. Doesn't hurt to try...

 

[theoldwizard1]

... I randomly decided to reset the pcm by unplugging the negative terminal and keeping my headlights on for about an hour, then i started it up and it drove better for 2 more days until the pcm learned all new input values and corrected itself to regain optimal performance.. 4 days after doing the reset it was hauling ass again but this time it stayed that way... it's been 4 months and no hick-ups since.....

Yep !

 

[WalleyeGuy]

Did you already replace the plugs and COP rubber things?

This post shows how plugs resolved my issue so far.

http://www.expeditionforum.com/thre...ine-missing-on-hills.32654/page-3#post-266945