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The O2 sensor on the car now would be a narrow band; probably can only see 14.5:1 to 15:1 or similar. A wideband gives the tuner more data; its going to be faster and more accurate when data logging. A modified engine is probably going to be tuned richer, something around ~12:1 and up. Being able to read those AFR's will let the tuner be able to customize/optimize your tune.

I'm sure Tom and others can chime in, this is just my high level overview
Our forward most sensor (upstream) is a Wide band, VIN confirmed.

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Discussion Starter #22
Yes the 2012-2017 has a wide band o2 sensor and yes I can see it when you send me a log

Can YOU see what the AF is why your driving WOT , No you cant but you need to be able to see what your WOT AF is so YOU know if it is safe and to let off if it is not

I like the AEM like C-F-M sells , there a great company to buy from and tell them I sent you and you want a good deal or use that part # to look other places

Driver needs to have the ability to see what the AF is all the time not just a couple times a year when you log

Tom
 

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So we would have to replace the stock o2 sensor with the aem one if we wanted to use that gauge correct?

We could just use the xcal4 too right?

What is the safe A/F number when driving normal and then when WOT?

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So we would have to replace the stock o2 sensor with the aem one if we wanted to use that gauge correct?

We could just use the xcal4 too right?

What is the safe A/F number when driving normal and then when WOT?

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14.7 is ideal A/F mix, that's 14.7 parts air to 1 part fuel. Lower numbers would be richer = Safer, higher numbers would be leaner = more dangerous

Lean engines run hot, and heat kills so that's what you want to stay away from. I'll let someone with more experience say what "Dangerous" is, but my rule of thumb has been that as long as I'm under about 16.5 A/F I'm doing okay. At WOT I'd want to see it a little on the rich side, say 13ish to make sure there's enough fuel.
 

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Cool, I'll plug my xcal4 in the next couple days abs see what mines doing.

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So i'm definitely considering buying the AEM gauge, i think it would be a worthwhile mod.

I Just want to clear some stuff up so i know what i'm doing when i get it. So I am currently running the fswerks header for the mk2 focus. Those of you who are familiar with it will know it only came with 1 o2 bung. I bought it used and the previous owner had a second o2 bung added in the collector right next to the one it came with.



Right now i have the stock down stream o2 sensor plugged into the second o2 bung just because. The down stream o2 is turned off with the tune.

First question, Can i just take the down stream o2 sensor off completely and run the new AEM o2 sensor in the second o2 bung?

Second question, does the AEM wideband o2 plug into the car it self or does it just plug directly into the gauge in the car? If that is the case, how do i get the wire from the o2 sensor into the car to attach to the gauge?

Lastly, if i keep the factory wide band o2 that is already on the car and then install the second wideband for the AEM gauge, when i data log, do i need to attach the AEM wide band to the xcal4 or can i just use the factory wide band i already have? if i could do that it would save me a few bucks have to buy the extra cable to attach the AEM wide band to my xcal4 when i data log.

Sorry for the newb questions i've just never done a wide band install before.
 

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Since we found out the the upstream O2 is a wide band if you are data logging with your Xcal device it will show you your afr (air fuel ratio). Now for using the AEM uego guage it's a whole package the WB sensor and the guage. You will need to mount the a guage pod to mount it inside the car. Now for the header since you mentioned that you have disabled the rear / downstream stock O2 you can remove it and mount the AEM WB sensor there.

Sorry I'm posting on my phone disregard any typos or errors lol
 

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#dailydriven
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Since we found out the the upstream O2 is a wide band if you are data logging with your Xcal device it will show you your afr (air fuel ratio). Now for using the AEM uego guage it's a whole package the WB sensor and the guage. You will need to mount the a guage pod to mount it inside the car. Now for the header since you mentioned that you have disabled the rear / downstream stock O2 you can remove it and mount the AEM WB sensor there.

Sorry I'm posting on my phone disregard any typos or errors lol
So does the AEM WB hook up directly to the gauge inside the car or does it plug into the car like the factory o2 sensor's do? If it goes directly to the gauge, how do you get the wire inside the car to hook to the gauge?
 

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Discussion Starter #31
The 02 bungs on the FS header should never of been placed where they engineered it , you want the o2 even the stock one to get a reading from all Cly

You would need to install your wide band AF Gauge past your flange in the pipe and have a bung welded in for it , you want to see a reading from all 4 Cyl not 2

You want the bung to be less the 1/2 inch TOTAL thickness 3/8 is ideal

What should the gauge read
Idle and cruise you will see anything from 13`s to 16`s depending on if you on or off the throttle you really dont need to worry about the AF ration at idle or part throttle/cruise

Its WOT you need to see and why your installing a wide band air fuel gauge , On the MK3 I have found that .84-.85 12.3-12.5 works best , in my opinions its the safest and best performance

On the earlier Zetec and Duratec I would shoot for 12.8 AF , the MK3 seems to like the added fuel at WOT

Tom
 

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The 02 bungs on the FS header should never of been placed where they engineered it , you want the o2 even the stock one to get a reading from all Cly

You would need to install your wide band AF Gauge past your flange in the pipe and have a bung welded in for it , you want to see a reading from all 4 Cyl not 2

You want the bung to be less the 1/2 inch TOTAL thickness 3/8 is ideal

What should the gauge read
Idle and cruise you will see anything from 13`s to 16`s depending on if you on or off the throttle you really dont need to worry about the AF ration at idle or part throttle/cruise

Its WOT you need to see and why your installing a wide band air fuel gauge , On the MK3 I have found that .84-.85 12.3-12.5 works best , in my opinions its the safest and best performance

On the earlier Zetec and Duratec I would shoot for 12.8 AF , the MK3 seems to like the added fuel at WOT

Tom
Thanks for the info Tom. So for those of us with the xcal4, we can use that to monitor the AF ration correct? just get a mount for it?
 

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Thanks for the info Tom. So for those of us with the xcal4, we can use that to monitor the AF ration correct? just get a mount for it?
xcal4 or any decent OBD-II sniffer, I've got a BlueTooth one that I connect to my phone to pull up gauges. I've used the AF since installing the TTR to make sure I'm in an okay region.
 

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what app do you use one your phone? What obd2 Bluetooth device did you get? i like that idea.
 

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what app do you use one your phone? What obd2 Bluetooth device did you get? i like that idea.
I've got the OBDLink Mx from OBDLink, OBDLink® - OBD-II Diagnostic Scan Tools for Android, iOS, & Windows | OBDLink® | OBD Solutions

The reason I went with them is their one of the few quality units out there that isn't a cheap Chinese piece. They also allow you to read/write which means I can clear codes and program through FoCCCus with the unit as well.

I use their stock app on an Android phone, the Mx doesn't work with iPhones (bummer since that's what I have as my main right now) but I had an old phone sitting around.

You can access so many gauges it'll make your head spin! And with cheap 7" tablets being what they are, you could easily add a nice heads up display that you can just leave in the car.
 

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Thank you for the info. For now, I just bought a cheap little vent mount for the xcal4. Once I get it I'll start monitoring the AF ratio.

Side note, what is a acceptable air intake temp? I want to see how how much of a warm air intake my short ram intake actually is.

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Thank you for the info. For now, I just bought a cheap little vent mount for the xcal4. Once I get it I'll start monitoring the AF ratio.

Side note, what is a acceptable air intake temp? I want to see how how much of a warm air intake my short ram intake actually is.

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Ideally, intake air temp should equal ambient air temp. For most of the other cars I've driven with stock air boxes, IAT tends to be about 15 degrees over ambient since they're pulling some engine bay air as well as fresh air.

I'd say you want to be no more than 20 degrees over ambient as a worst case, but this needs to be evaluated while moving, as everything heat soaks if you're standing still. Things like the Velossa Tech Big Mouth intake are worth it because they help kill that 15-degree rise over ambient.

Coolder air = Denser air, and Denser air = More power!
 

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So if it's 60 degrees outside I should see between 60-80 degree intake Temps?

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Got a vent mount for my xcal4 so now I can use the gauges. Just have to figure out what to do about the cord.i can't close the access door to the obd2 when the cord is plugged in and the cord itself hangs in the way.


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Got a vent mount for my xcal4 so now I can use the gauges. Just have to figure out what to do about the cord.i can't close the access door to the obd2 when the cord is plugged in and the cord itself hangs in the way.


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I'm working on that same issue now. I've got my bluetooth adapter but I can't close the door with it installed. Working on a new piece of plastic that will slot in where the OBD-II is now to re-align the connector up since there's plenty of space in the dash for the connector to live.
 
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