AFR's

[supraguy17]

So last night I put on my new setup and my profile is up to date besides having the 255 put in, won't be able to get to it till next weekend.

I am open down pipe right as today was my only day off, the old exhaust was the original o2 housing and stock cat but now I'm going cat-less and no one had an opening till later in the week to get my flange welded on to connect the down pipe to the rest of the exhaust.

So at idle I know I'm supposed to be right around 14.5 is the target afr, on link it says that, I'm dead on with it hovering right around 14.5 but my wideband bounces around from 15.1 to 16.2 or so, which should I go by? I've been told to not go by the one on link and just my wideband?

Thanks in advance, I can upload a log as well if anyone needs.

 

[MichaelSuch]

Is your wideband wired in the ECU for logging? If it is not and you are reading the AFRest value, that is just an estimation based on commanded airflow and fuel from the ECU. It has no way of telling what the ACTUAL AFR is.

Ideally you want your actual AFR and AFRest value to match. You can do that by adjusting your MAF sliders.

quickieafsetup [ECMTuning - wiki]
v3mafadjcombft [ECMTuning - wiki]
ecmlink101initialchecks [ECMTuning - wiki]

 

[supraguy17]

^no it's not it's just plug and play. When I'm cruising it is dead on as well right around the 14.3-14.7 range and when WOT it's about 10.1-10.6, but idle its about 15.6-16.2.

 

[Achelea]

I'm glad Micheal lives close to me. Parts are coming in. Muahahahahh

Soon, Kiara will rise...

 

[boost97gst]

Ive been through every single wire in my setup (lc1 wb, db guage, link v3) and i CAN NOT get links lc1 afr to match the afr on the guage. Is that the problem ## having? I personally trust the link setting.
Have you tried lmconfig if you have an innovative product?

My guage reads 1 point richer. I have to go by links lc1 afr value over the guage due to butt dyno and knock results. It runs was better at 11:1(guage indicates 10:1 ) and if i bring it up to 12:1( where guage will read 11:1) i get knock fast n hard. My guage must be whhhhhacked out

 

[crash89]

Where is your bung for your sensor welded in? Or are you using the stock rear o2 bung since you went cat-less?

If you're using the rear o2 bung and running open down pipe you will show a little lean durning idle on your gauge since some outside air will get getting read by the sensor. This could also be true during cruise as well. I had a similar issue when I went open DP for a couple days, tune was spot on with the full exhaust then the wb gauge was reading way off without the catback.

Going by one of my previous logs at idle Id say reading at 15-16 a/f at idle is pretty normal. And even currently, whenever my car idle my WB shows the same.

 

[twowrongs]

Where is your bung for your sensor welded in? Or are you using the stock rear o2 bung since you went cat-less?

Right, if you have your WB plumbed into your down pipe it is possible that you have a leak at the O2/down pipe junction. This leak, at idle, could cause air to be drawn into the exhaust stream and cause your WB to read lean.

If this is the case, and you do not have a leak up stream of your 02 sensor, and/or you can see your the O2 cycling (in closed loop) in your logs. It is likely you are in fact idling around 14.7.

Before you get too far ahead of yourself, i would make sure that your down pipe flange is flat. Sometimes they are sent out slightly warped. Use a good gasket and make sure its tight. Having this piece of mind while WOT tuning makes the process much easier, with less second guessing.

Best of luck

 

[supraguy17]

Right, if you have your WB plumbed into your down pipe it is possible that you have a leak at the O2/down pipe junction. This leak, at idle, could cause air to be drawn into the exhaust stream and cause your WB to read lean.

If this is the case, and you do not have a leak up stream of your 02 sensor, and/or you can see your the O2 cycling (in closed loop) in your logs. It is likely you are in fact idling around 14.7.

Before you get too far ahead of yourself, i would make sure that your down pipe flange is flat. Sometimes they are sent out slightly warped. Use a good gasket and make sure its tight. Having this piece of mind while WOT tuning makes the process much easier, with less second guessing.

Best of luck

^thanks to the both of you. My wide band bung is in my downpipe about 2 feet from my turbo. The flanges on both in and out points are flat. Would it make any difference that I'm running and evo3 o2 housing and not the stock? I figured they were right around normal because when crusing im dead on at 14.5-14.7 and wot im 10.1-10.5, both in link and my wideband but at idle like stated its about 15.4-16.2 on the gauge and ~13.7 in link. I haven't neccissarily pulled nay timing yet just a tad amount but i'll get phantom knock once in a blue moon

 

[bring_1]

Try another O2. They dont live forever

 

[WES_393]

Your AFR at idle should be 14.7, or at least hovering around it. It's likely that an exhaust leak is throwing off your wideband giving you a lean reading. If its also affecting the front O2 signal then it will cause the ECU to richen the fuel mix, which would explain the rich estimate in Link. Fix the exhaust and it will fix your AFR problems.

 

[spyderturbo007]

Mine does the same thing and I wouldn't worry about it if I were you. I'm sure I have a small exhaust leak somewhere that's allowing a little air in the system during periods of low flow, i. e. idle. Mine floats between 14.9:1 and 15.4:1. As soon as I hit the gas it drops right down to where it should be.

I've spent time in the past trying to pin down the leak, but I don't have any desire to spend the money for a smoke test.

 

[supraguy17]

Thanks for the advice guys, I will track that leak down when I finish the exhaust up!

 

[reallyslowfwd]

little bit of sea foam into the intake at a vacuum source will tell you exactly where your exhaust leak is

 

[spyderturbo007]

That works too, but I'm not a big fan of running that through my engine. I'm sure it doesn't do any damage, but I still stay away from things like that.