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Thread: Wideband: How far is too far?

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Posts: 1-10 of 16
2011-11-21 22:16:04
#1
Wideband: How far is too far?
Temporarily, I have my wideband on the SSAC downpipe, which is fairly far back. Especially for AEM UEGO's recommended 18" for NA. My readings seem to be a bit off, 1 AFR too rich then it really is. I noticed the car felt slow when I tuned it to 12.8-13, then I enabled the O2 sensor and while cruising it would be 13.8-14.3 AFR. While I was turbo, the front O2 would always show 14.5-15.3 like it should normally, so I don't think it's a bad front O2.

Thus I'm thinking my wideband might be a little too far back, hence my readings are off by 1 afr or so.

Location is where the bung at.
2011-11-21 22:20:53
#2
The readings are all correct for the gas by the sensor. The only trouble with being far away is that you're getting "old" data. The data is correct for some time in the past. It's not like oxygen somehow gets into the system and makes it read differently. (Assuming no leaks.)

The sensor will take longer to reach operating temps and the heater will have to work harder, but no big deal I guess.
2011-11-21 23:55:20
#3
When I installed my AEM UEGO, I had two bungs welded into the pipe after the flex. The first location is right after the flex and the second location was about 4-6 inches before the cat. I originally installed it in the front location but when I was testing an Innovate LM-2 I moved it to the back location. The difference is about 12". I did not notice any difference in the readings. I have given the LM-2 back to the friend who lent it to me and moved the UEGO sensor back up to the closer location. AFR's did not change. I decided to put the sensor after the flex because in this loaction it is far enough away from the exhaust ports to keep the sensor functioning over a longer period of time and for ease of installation as well. I figured it would be more accurate here because all of the cylinders are merged into one and therefore I receive an equal reading of the engine overall. My guess was this was better than having it in one of the secondaries or primaries as far as accuracy goes. I would think that having it anywhere other than after the 2-1 merge is only giving you a partial picture of the four cylinders.

The Hotshot header I have is similar in design to the SSAC 4-2-1. Here are the two locations I had welded in, with the location closer to the flex being where my sensor currently resides.

Vadim, I hope you don't mind me using your picture...

2011-11-22 14:45:39
#4
Alright it must be something else then. Though Ashton did mention that having it to far could lead to richer readings (exactly what I'm seeing).

I think I might have an exhaust leak between my primary and secondary, even with a copper gasket . Guess I'll remove it again and check to make sure!!!
2011-11-22 14:53:25
#5
mines welded in right after the flex. too. the second bung just barely hits the shift linkage so i could'nt use that spot.
2011-11-22 15:40:50
#6
Guess I'm the oddball. Mine was welded in just after the merge, before the flex.
2011-11-22 19:02:31
#7
Originally Posted by Cliff
Guess I'm the oddball. Mine was welded in just after the merge, before the flex.


I'm tempted to reweld mine there, but would have to weld it at 9 or 3 o'clock.
2011-11-22 19:26:30
#8
Originally Posted by Cliff
Guess I'm the oddball. Mine was welded in just after the merge, before the flex.


This is where I wanted mine and is the closest it can be and still get flow from all primaries. Was just easier for me to put it after the flex. However, I do think my Hotshot header has slightly longer secondaries than on the SSAC so it puts it a wee bit further back.
2011-11-22 19:27:35
#9
I put mine at about 10 o'clock if looking from the rear of the secondary towards the front. It was a tight fit, but we spec'd it with the car on the lift to make sure it would clear before cutting/welding. As long as it's not between 4-8, you should be fine as far as moisture is concerned.
2011-11-22 20:02:40
#10
Now I'm curious on if a exhaust leak could be doing this. I figured an exhaust leak, would would suck in air thus cause it to read leaner not richer...
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