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Both Downstram o2 sensors running rich
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twk3
User
May 17, 2013, 11:23 AM
Post #1 of 18
(4425 views)
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Both Downstram o2 sensors running rich
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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?
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Discretesignals
Ultimate Carjunky
/ Moderator
May 17, 2013, 11:25 AM
Post #2 of 18
(4415 views)
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Re: Both Downstram o2 sensors running rich
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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.
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HT
User
May 17, 2013, 11:26 AM
Post #3 of 18
(4412 views)
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Re: Both Downstram o2 sensors running rich
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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.
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twk3
User
May 17, 2013, 11:40 AM
Post #4 of 18
(4407 views)
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Re: Both Downstram o2 sensors running rich
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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
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HT
User
May 17, 2013, 12:00 PM
Post #5 of 18
(4395 views)
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Re: Both Downstram o2 sensors running rich
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The computer monitors all that stuff in real time and if there is a problem, it will set a code.
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twk3
User
May 17, 2013, 12:10 PM
Post #6 of 18
(4388 views)
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Re: Both Downstram o2 sensors running rich
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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)
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HT
User
May 17, 2013, 12:56 PM
Post #7 of 18
(4375 views)
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Re: Both Downstram o2 sensors running rich
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You can't trust the scan tool you're using is updating fast enough to even reflect the changes.
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twk3
User
May 17, 2013, 6:56 PM
Post #8 of 18
(4352 views)
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Re: Both Downstram o2 sensors running rich
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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%
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Discretesignals
Ultimate Carjunky
/ Moderator
May 17, 2013, 7:03 PM
Post #9 of 18
(4348 views)
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Re: Both Downstram o2 sensors running rich
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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)
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twk3
User
May 17, 2013, 8:01 PM
Post #10 of 18
(4338 views)
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Re: Both Downstram o2 sensors running rich
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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)
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
May 18, 2013, 1:26 AM
Post #11 of 18
(4323 views)
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Re: Both Downstream o2 sensors running rich
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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
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HT
User
May 18, 2013, 3:03 AM
Post #12 of 18
(4315 views)
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Re: Both Downstram o2 sensors running rich
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twk3............... you need to delete those links and not post any more.
Read the FORUM RULES
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twk3
User
May 18, 2013, 2:02 PM
Post #13 of 18
(4301 views)
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Re: Both Downstram o2 sensors running rich
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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.
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HT
User
May 18, 2013, 2:26 PM
Post #14 of 18
(4293 views)
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Re: Both Downstram o2 sensors running rich
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That could have a lot to do with the temperature of the Cat.
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twk3
User
May 18, 2013, 3:30 PM
Post #15 of 18
(4288 views)
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Re: Both Downstram o2 sensors running rich
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Thanks for help guys.
(This post was edited by twk3 on May 18, 2013, 3:30 PM)
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nickwarner
Veteran
/ Moderator
May 21, 2013, 7:53 PM
Post #16 of 18
(4256 views)
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Re: Both Downstram o2 sensors running rich
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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.
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williammack
New User
Nov 5, 2013, 11:23 PM
Post #17 of 18
(4054 views)
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Re: Both Downstram o2 sensors running rich
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Hello Guys,
I am new in this forum.
Please also join me.
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Hammer Time
Ultimate Carjunky
/ Moderator
Nov 6, 2013, 3:23 AM
Post #18 of 18
(4049 views)
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Re: Both Downstram o2 sensors running rich
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ByBy spammer
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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.
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