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UEGO bung location for aem afr gauge

6K views 44 replies 14 participants last post by  S0C0nFused 
#1 ·
OK, I have a stock cat on a 2.0 duratec. I will be purchasing the xcal 3 and aem afr gauge soon. For the location of the bung to install the UEGO sensor Is its ideal to install it as close as possible to the first O2 sensor of the header coming from the engine? Does anyone have any pictures on this that they can post?
 
#3 ·
If you locate it before the cat by (or close to) the 1st o2 sensor (the one that is threaded into the cast iron neck) your technically to close to the engine and it will burn up the wideband (that is what I read, although the discussion seemed to be tilted towards HP V8's). I tried to get info if it would be possible to locate the bung around the 2nd o2 sensor (the one located in the SS canister, but ahead of the cat supposedly). This would be better heat wise, but it may be to far out of the exhaust stream to give you a trusted reading. That leaves only a location after the 3rd o2 sensor (down by and right before the flex pipe). The issue is that you will be trying to read your A/F minus the A. And it is noted that as the cat ages the A/F reading will change. It is not possible to thread another bung into the cast section (I checked with some folks who would know). therefore, the best that is possible would be to have a SS 'cone' made with a bung that would position the wideband 02 sensor deeply enough into the SS canister and before the 2nd o2 (and after the 1st o2) and in such a manner as to negate the effects of the volume increase of the canister. To do this properly will require a sacrificial exhaust manifold that you can dissect to determine the proper points and dimensions. Most folks just go with putting it near the 3rd o2 (down by the flex) as it is weldable and accessible, and make a mental note that the reading is off by a few points.
Have fun with it. [wiggle]
 
#4 ·
just buy a header and put a high flow cat in your exhaust (check with local emission laws first). The stock manifold, cat and flex pipe are very restrictive. The tune will disable the rear 02 sensor. But you definitely want to put the wideband 02 sensor before any cats.
 
#5 ·
This would work except for >> The vehicle will (of course) immediately fail any emissions tests if required for all the obvious (legal) reasons. But just be aware that the main issue with moving the cat downstream is due to startup (when the engine is running at it's richest). The smog guys want the cat to heat-up as quickly as possible. We had a discussion about this a good while back (going so far as to contact the responsible parties within the Fed Gov). The answer was no, not with a standard cat. Now there is a type of powered cat (Tom gave me the type once) that could be used as it does not depend on the exhaust heat for warm up. But there very expensive. However, they are a high performance part, but I have never found one at any of the normal retail channels (note: I did not look that hard). I would be curious to know if these are even available in a size our focus could actually use. [wiggle]
 
#13 ·
General group question. Is anyone aware of a location in the country where they actually DO a cold start sniff test?
Tom >>
You think the wideband will have sufficient exhaust flow? (Yes I am aware that the bung is somewhat imbedded deeper into the canister, but its only ~1/2").
 
#14 ·
I'll do the 2nd o2 from what tom said for now. I live in illinois and its illegal to remove the cat but I have gone to do my emmision testing and they do not check under the hood or sniff the tail pipe. They just do the obdII. So I think I would be fine as long as I do not get a failed signal on the o2 sensor readings, which from what Tom said, it should not be a problem if the rear o2 sensor is disabled (this I have to test out unless someone has done it already in illinois).
Also, Im just setting up for a turbo in the future and a header would be a waste of money for me unles I get another focus or I could sell it locally...
 
#16 ·
You are right on IL my buddy has a 2.3 swaped turbo focus which has a cut off after the down pipe and he passed emmsions in IL

I am emissions certified and In IL what they told me about people like us" that cheat the test" is that is to small of a percentage to worry about

So if ur in IL and the tune disables the rear O2 you'll be fine
 
#20 ·
i would recommend putting the sensor BEFORE the CAt. I was told this buy a fellow SCT tech. and a AEM tech. reason is, installing after the cat will cause the reading to flux. you won't get a accurate reading. the flow of flume builds up in the cat and release a reading only a wack job can read.


when i had mine in my second o2, i had reading from 11 to 14..... and it should of really been around 11 to 12, 13 is getting close and 14 is past....


just my cent... but what do i know?
 
#22 ·
I need it to be good enough for Tom so if that loaction is good enough for him for tunng it should be okay for now. This location will not be its permanent home either way.
 
#30 ·
Lol! Ok, your not 'getting it'. let me try again. Your gauge measures the air/fuel ratio, it does not control it. Your air/fuel ratio is controlled by the sensor in (refer to your pic please) the number 1 bung hole. IF you remove that sensor, then your ECU (which controls your fuel injectors via input from the sensor in #1 hole) would have no reference to know how much fuel to add or subtract. I suspect that with no input, it would just keep adding fuel in an attempt to get some kind of reading (would it simply assume no fuel? That is what I am unsure about). Regardless, you car won't be able to run without sensor #1. Sensors #2,3 are for measuring the health of your catalytic converter. Note that sensor #2 resides right in the middle of it in the 'canister' portion (well, actually, that is an assumption as noone has ever taken one apart to know if it is in the cat or right before it. but based on it's location and the size of the canister make up your own mind). Regardless, it is a very poor location for a wideband as you want the exhaust gases flowing in close proxity to the wideband sensor. the canister is to big thus 'diluting' the mix. Hence, your only location left would be after the cat near #3. But as you already have a sensor stuck in the pipe at that location (assuming you keep it thus avoiding having to rig up a cheater), that leaves you with only the flex pipe or somewhere more 'downstream'. Typically, you would locate a wideband sensor in the collector of the manifold anyway (where the gases come together from the exhaust ports). So that is really your only option as regards the stock mani-cat.
Better? [cheers]
add > I read what your wrote about heatsinking the wideband. Discounting that you cannot drill and tap a bung into the cast material, I think there wrong. See, aftermarket headers are made from tubular steel. Hence, they dissipate heat much faster than a cast unit. That being known, If you were to add a heatsink (such as a piece of copper on the wideband sensor), it would heatsink the entire cast portion of the upper manifold (as it is coolest, heat would flow to it). Tween you and me, that's a lot of heat. And if your sitting at a stop light, you don't even get the advantage of airflow. So without that, the wideband is going to cook.
 
#31 ·
I get what your saying but your not 100% what its doing or what will happen thats why im still asking. Till i find out a for sure thats what the top sensor does or what happens if its removed and replaced with the wideband.

Ive read that that top sensor is not as sensative as a wideband sensor so how accurate can it be for setting the A/F? If its in a spot that runs 1000-1200° how can it survive?

They already make a sink for the wideband to put it into the manifold but they are WAY over priced. On the innovate forum they say its not the tip that is critical to heat its the base that needs to stay below 900F Thats where the sink comes in.

 
#32 ·
Put your widedand in the 2nd bung hole location. When you get a tune that will disable the 2nd o2 so you don't trip a light. When emission testing day comes along. Swap your wideband back out for the OEM one. Then either flash back to stock or ask your tuner to send you file with the rear o2 ON. That will allow you to pass. I just went through that whole ordeal to pass emission in PA. The problem is when you turn the rear o2 off. The emission system goes into a "not ready" status. Due to that the guy at the emission place can't test the car. Swap the sensor, drive around a few miles (you need to so the system goes to a "ready" status) and get the test done. Now I have an 09, so I'm not sure how the earlier years work with their emission systems.
 
#36 ·
I have the AEM it works really well. As for some of the earlier posts, you need the 1st o2 in that location. The ECU uses the inputs from that sensor. The 2nd sensor is just using a cat monitor which is just telling the ECU ithat the cat is doing it's job. So swapping if for your wideband isn't going to effect engine performance.

The wideband will be on of your best tools while tuning.
 
#37 ·
Cool, thanks. Im not planning to get a tune for a few more weeks. Im going to just drive it with the CEL for a while with thewideband in that location.

Did you put a heatsink or anything on your sensor in the second location?
 
#39 ·
Here is a post i got from the innovate site, tell me what you think.

It's a 3way Cat. 3way cats are comprised of 2 half converters.

First half is a reduction cat for NOx.
Second half is a oxidation cat for HC and CO.
The first half helps supply O2 for the 2nd half.

First bung is before the cat does anything.
2nd bung is after the reduction phase.
3rd bung is after the oxidation phase.

So with the 3 locations you can figure out how each half of the cat is working.


If the middle isn't for a O2 sensor, it could be used for a temp sensor to avoid overheating the converter.
Then another user,

All KAT's, especially the one using NBOs, are Three-Way-KAts because the process three not allowed emissions that's why the was called Three-Way-KAT.
Rest-Fuel and CO, combusted, NOx reduced, that happens in parallel.
For the Warm-Up-Phase after an Cold-Start some Car's use Start CAT's having an slightly other composition because the Emissions are rich at Warm-Up condition.


Interesting is this for sure?

#1 an NBO2 can Control best efficiency of the KAT.
#2 can be an WBO2 to Tune for rich and lean.
#3 an NBO2 is the Monitor Sensor for OBD.

That's how I think it work.
Different Countries have different Emission restrictions, so it seems possible that Ford use different Sensors in the three Bungs.
All EFI's using NBO2's do all the AFR controlling only to make the KAT happy.
 
#40 ·
VERY interesting. A 3-way cat. Never woulda thunk it. I have no clue as to what kind we have though and the effect on the wideband. But, I would think this would be valid >> The ECU maintains a 14.1 lambda when closed (input from MAF and 1st o2 sensor). OK. So if you are running good fuel, and you don't have a lot of miles on the car (I.E. the cat is in good shape. I have no idea how to statistically age a cat though). Then IF, your A/F gauge is reported 14.1 A/F ratio, then I would conclude the effects of the very 1st cat (within the mani-cat) has negligible effect. That would be MOST interesting to know.
Good info there from innovate. Nie job!
 
#41 ·
lol, nice job? i have no idea what any of it means though. Do you understand it?

When i hooked my wideband to the rear of the tail pipe on my car yesturday and ran it around the block i got an average of 14. i thought that was to lean? I thought it was supose to be around 12-13
 
#42 ·
Lambda (or stoichiometric ratio) is 14.7. So I wrote it wrong. sorry. So if you reading 14.0, then that indicates rich I think. Search for 'stoich' on this forum as I know there are scads of discussions on it.
go here to read a bit about A/F ratio.
http://en.wikipedia.org/wiki/Air-fuel_ratio

I can follow emsvitil, but not sure about SprungSonde as he writes as if english in not his/her 1st language. I cannot decipher his acronyms. [scratch]
 
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