Main IndexAuto Repair Home Search Posts SEARCH
POSTS
Who's Online WHO'S
ONLINE
Log in LOG
IN







Search Auto Parts

Both Downstram o2 sensors running rich


  Email This Post



twk3
User

May 17, 2013, 11:23 AM

Post #1 of 18 (1556 views)
  post locked   Both Downstram o2 sensors running rich  

2010 Ford Edge Limited
80 000 kms

I've been having poor gas millage in town ever since I purchased it in February. Avg 16L/100kms. Hooked the OBD2 up to it yesterday, didn't have any fault codes, but both downstream sensors are always around 0.8V. At idle, and at all speeds.

From what I've been reading that sounds like it's running rich. The pre-cat sensors appear to have proper wavelengths. But I'll check again later today to make sure they weren't running a little rich.

Am I correct in thinking that 0.8V is a problem for the downstream sensors. And being that both are reporting that, what do you think might be the problem?


Discretesignals
Ultimate Carjunky / Moderator
Discretesignals profile image

May 17, 2013, 11:25 AM

Post #2 of 18 (1546 views)
  post locked   Re: Both Downstram o2 sensors running rich  

What are the long and short term fuel trims?

Create a vacuum leak and see if the O2 sensors and fuel trim respond.





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.


HT
User

May 17, 2013, 11:26 AM

Post #3 of 18 (1543 views)
  post locked   Re: Both Downstram o2 sensors running rich  

No, that doesn't indicate anything rich if the front are working properly. The rear sensors are there to determine the condition of the cats only.


twk3
User

May 17, 2013, 11:40 AM

Post #4 of 18 (1538 views)
  post locked   Re: Both Downstram o2 sensors running rich  

What is expected from the downstream readings then? Yesterday one of them was flatlined at 0.8V, and the other was in flux, similar to it's pre-cat sensor (but not quite as extreme), but today both were flatlined at 0.8V


HT
User

May 17, 2013, 12:00 PM

Post #5 of 18 (1526 views)
  post locked   Re: Both Downstram o2 sensors running rich  

The computer monitors all that stuff in real time and if there is a problem, it will set a code.


twk3
User

May 17, 2013, 12:10 PM

Post #6 of 18 (1519 views)
  post locked   Re: Both Downstram o2 sensors running rich  

Okay, I will add the trims when I get my tools back later today, and keep an aye on the bank 2 downstream sensor to see if it makes more movement. Sounds like stead 0.8V is fine, it's the change that it measures.


(This post was edited by twk3 on May 17, 2013, 12:20 PM)


HT
User

May 17, 2013, 12:56 PM

Post #7 of 18 (1506 views)
  post locked   Re: Both Downstram o2 sensors running rich  

You can't trust the scan tool you're using is updating fast enough to even reflect the changes.


twk3
User

May 17, 2013, 6:56 PM

Post #8 of 18 (1483 views)
  post locked   Re: Both Downstram o2 sensors running rich  

So drove for about an hour today, for the first couple minutes of driving after each engine start one of the downstream o2 sensors has quite a bit of movement, climbing from 0.3 to 0.8 back and forth, but much slower than the pre-cat ones. The other downstream sensor is always around 0.8

fuel trim bank 1 sensor 1 was always between -2% and 4% bank 1 sensor 2 was always 99.4%, bank 2 sensor 1 was always between -2% and 13%, bank 2 sensor 2 was also always 99.4%


Discretesignals
Ultimate Carjunky / Moderator
Discretesignals profile image

May 17, 2013, 7:03 PM

Post #9 of 18 (1479 views)
  post locked   Re: Both Downstram o2 sensors running rich  

Disregard the Bank 1 Sensor 2 and Bank 2 sensor 2 fuel trims. They are not used for fuel trim.

Is this long term or short term? It doesn't appear to be any problems with fuel trim so far.

The O2 sensors after the cats will probably stay steady around .7-.8 volts when the cats are operational. That is because the cats are using up the oxygen that's in the exhaust. That tells you the cats are working.


You fuel mileage is pretty close for city driving. In the city your vehicle was rated around 17 miles/gallon or 27kms/3.7L.

http://www.fueleconomy.gov/...2010_Ford_Edge.shtml





Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on May 17, 2013, 7:27 PM)


twk3
User

May 17, 2013, 8:01 PM

Post #10 of 18 (1469 views)
  post locked   Re: Both Downstram o2 sensors running rich  

I think I'm the worst on fuelly for 2010 ford edges at the moment. Which is part of the reason why I started looking into it. Most of my city driving is on 50km/h roads, so I wasn't expecting to have the worst data points.


(This post was edited by twk3 on May 18, 2013, 12:25 PM)


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

May 18, 2013, 1:26 AM

Post #11 of 18 (1454 views)
  post locked   Re: Both Downstream o2 sensors running rich  

Just comments on fuel consumption: That is so hard to get a real grasp on. Yes - vehicles get rated for what to expect in some controlled conditions no doubt with probably ONE specific blend of fuel. Gasoline is not near 100% fossil fuel anymore - not even close!

TMK there are about 200 different formulations for the US and no telling what Canada does or other places. They should sell fuel by weight not volume such as liters or gallons. A gallon of real fossil fuel (best for most) can weigh a pound more than what we buy per gallon! That pound is fluffed that makes the measure correct but not the actual available ability of pure stuff. Factor that.

The exact conditions you drive in can't be the same as every place nor your driving habits. A moped running and sitting still is averaging in ZERO yet consuming fuel.

So many variables as said including air temps, temp of fuel when purchased, plain tires account for a fair amount of differences by type, size, air pressure, and wear. Is odometer reading properly and so on.

In short if running well with no known real faults this could be normal IMO,

T



HT
User

May 18, 2013, 3:03 AM

Post #12 of 18 (1446 views)
  post locked   Re: Both Downstram o2 sensors running rich  

twk3............... you need to delete those links and not post any more.

Read the FORUM RULES


twk3
User

May 18, 2013, 2:02 PM

Post #13 of 18 (1432 views)
  post locked   Re: Both Downstram o2 sensors running rich  

Sorry I didn't have the right data on the trims, Both shorts terms were between -5% and 5% both during idle and at 2500rpms. Both long terms between -2% and 2%, I actually got a calculated Air/Fuel mix at a constant 14.7:1, so it looks like everything is working properly.

I'm still curious about the downstream sensors, and why the one is irratic for the first couple minutes of driving, and I noticed today that other one drops quickly from 0.8V to 0.3V when rpms are over 2000, and stays there until I let up.


HT
User

May 18, 2013, 2:26 PM

Post #14 of 18 (1424 views)
  post locked   Re: Both Downstram o2 sensors running rich  

That could have a lot to do with the temperature of the Cat.


twk3
User

May 18, 2013, 3:30 PM

Post #15 of 18 (1419 views)
  post locked   Re: Both Downstram o2 sensors running rich  

Thanks for help guys.


(This post was edited by twk3 on May 18, 2013, 3:30 PM)


nickwarner
Veteran / Moderator
nickwarner profile image

May 21, 2013, 7:53 PM

Post #16 of 18 (1387 views)
  post locked   Re: Both Downstram o2 sensors running rich  

Your economy at 50km/h is going to suck no matter what. Looking at my speedo 100km is about 67mph and that puts you under 40mph so city driving. You need to remember that driving in town eats way more gas than the highway does.


williammack
New User

Nov 5, 2013, 11:23 PM

Post #17 of 18 (1185 views)
  post locked   Re: Both Downstram o2 sensors running rich  

Hello Guys,

I am new in this forum.

Please also join me.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Nov 6, 2013, 3:23 AM

Post #18 of 18 (1180 views)
  post locked   Re: Both Downstram o2 sensors running rich  

ByBy spammer



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.







  Email This Post
 
 


Feed Button




Search for (options) Privacy Sitemap

shopify
site analytics