Yes, I think 4 sensors, fore and aft of the first cat, at least that is the way it is on mine...I would think that if you aren't getting something from the O2 sensor in TP, then yes, I would think about replacing it. Are these supposed to be replaced in pairs, or all four?

 

Mornin fellers;

I think a good place fer yall to start is the OBDII publications from Ford, which is specific to each Model Year.

Find and download the PDF's from www.motorcraftservice.com , left pane you'll see "OBDII Theory & Operation" - click on that and select yer year truck.

That will help with data interpretation - it will be yer 'bible', lol.

As fer O2's, yes - change in pairs. The front units are the crucial ones that affect A/F's; the rears are CAT monitors and typically need replacement only after many miles, or they outright drop dead / set a code. It's also recommended to use only Motorcraft O2's ( for the fronts) - here is why:

http://vmptuning.com/forum/showthread.php?t=825

If yer not seeing a signal from an O2, remember that the OBDII ongoing sanity checkin' routines will catch that immediately and set a CEL & code. So if the app isn't displaying same, my humble guess is it's a bug, or a problem with the BT ( Torque's forum lists tested BT adapters for a reason - a lot of the cheap ones do funky things like this - just fyi). You can test this - simply unplug any O2 to simulate a sensor failure - and see what happens

Normal temp ranges - fer a 4R70/ 4R75, optimum trans temps are ~170 deg F (that's the nominal setpoint for the trans fluid bypass valve between trans and the cooler(s). Anything over ~200 deg F for any length of time is starting to need scrutiny; ~230 and above, MerconV is being damaged ( Amsoil ATF can go higher).

Engine oil temps - 230-250 (or thereabouts) degrees is considered normal - as long as yer engine is within normal temps (195-205), the engine cooling system is healthy, and you have a full oilpan you need not be concerned with engine oil temps unless yer in a racecar, lol.

Hope this helps a litle.

good luck!


MGD

 

Yes, helps alot...I get "ok" sensor readings on banks one and two on the O2's, but again, the range that TP is ok, is vast...I would like to know ultimately what a proper ratio is, or exhaust back pressure is (the is a gauge for that, but I am not sure it works on these trucks). In that way, I would hope to see a plugged up cat happening before it happens...I think I have read that if the exhaust temps are really hot before cat and really low after, there is a problem, right? But we don't have sensors for temp, only O2 before and after, correct? If I need a weekend project, would changing the O2's for the hell of it be worthwhile at 94k miles? I want to do the TPS to see if it would fix my tough idle, but not sure that is worthwhile either...

With my new dual pan drops and clean MercV I am not getting over 150 degrees on the tranz (nice thread reference, huh?) and in the 180's generally in coolant. I can't see the oil temp, not even sure this truck registers that...

Edit - I looked at that Ford OBD .pdf for 2005 model year, and it really didn't seem to have thresholds, it also refers to a lot of other manuals...was rather confusing, but I am shoveling through it. Seems to be primarily for CEL diagnosis, not monitoring?

Thanks for the reply MGD, keep it coming!

 

Hi.

94K miles? Yep - the fronts could use a fresh pair of O2's.

Yep - if the inlet/outlet temps are vastly different, the Cat is on it's way south. I just use an IR point&shoot temp gun on 'em to check them.

If yer mileage is taking a dump and the truck is a dawg, could be front O2's and/or cats. Misfires, over time, will destroy both due to all the raw dumped fuel downstream.

good luck
MGD

 

I think I love you.

 

Also, MGD, I've had the 0171 and 0174 codes all winter. I just erased them last night, so I don't think my 15 minute trip to work was quite long enough for it to come on, if the O2 sensor is the culprit.
I could be wrong, but I'm waiting for it to come back on.

EDIT: After looking through "The Bible", it appears the O2 sensors would have absolutely nothing to do with the P0171/P0174 codes.

 

What are some good O2 sensors?

 

Hi again;

OK, here's some more info: http://www.fordforumsonline.com/thre...al-modes.3270/

A lot of stuff looks hyperlinked in there - I think it requires you to register to gain access to the linkies (it is Free, though).

Another source of interesting info is Flatratetech.com, specifically, their "Resources" section: http://www.flatratetech.com/resources.html

It's a HUGE site - lots of PDFs, and further down a vast selection of training videos, including one on Cat converter diags & repair, lol. Keep on scrolling, it's a Looong list of chit, lol. (The vidyas are in WMV format, so you'll need Windows Media Player support).


Have fun, fellas!


MGD

 

Hi.

Motorcraft. Get 'em from Rockauto.com.

good luck
MGD

 

Go to fordparts.com and enter your VIN number, then find the part numbers and/or connector colors that fit your engine. There are quite a few different O2 sensors. Once you have the part numbers/connector colors, you may need to look at your old one to verify the correct connector color.
This could also be wrong, but based on what I've found, comparing old with new seems to be the only way to get the correct design.

Then go to Rockauto.com to buy them...much cheaper than most everywhere else.