AEM wideband sweeping

[Nate2SS]

Hey all, I recently got my wideband working in my car and had a few questions regarding the numbers I'm seeing.

On idle I see anywhere from 13-16. I understand this sweeping is normal as the computer is constantly making adjustments for stoich ratio.

On WOT I see anywhere from 11-13 sweeping which I understood is not normal as the car should be pulling from the tune to have the right ratio. Someone please explain if this is incorrect.

I lugged the car in 5th gear in an effort to see PE and am getting 11.5 consistently. This is the only time I ever see a super consistent range.

I understand sweeping is okay on light throttle and idle but how far should it sweep?

I will be calling AEM in the morning to get a better idea of what they think it is but wanted to see if anyone else had similar experiences?

[Badbubba]

That's a large swing. Is the AEM able to be switched to lambda instead of afr? I have an AEM 03-0300 in my STI and switched to read lambda. It is rock solid at 1.00 at idle. The Autometer in my Camaro bounces from .95 to 1.02 at idle. Having a wideband that displays afr is tricky. Because the stochiometric value can vary due to the gas. Gas with 10% ethanol is 14.1. Straight gas is 14.7. Your wideband will either have a fixed value or a programmable value. That value needs to match the gas stochiometric value. If not, you'll need to add or subtract an amount to get the correct afr. My guess, the AEM is reading correctly and the cam/tune is responsible for the swing. NA cars should be about 12.5 afr, forced induction 11.5. Provided you made the corrections for gas and programmed stochiometric values. Lambda is just lambda. At idle it should be about 1. Wot NA .85 and FI .78. If you wanted to convert to afr, multiply the lambda value by the fuels stochiometric value.

[CamaroDreams76]

That is a bit strange and a rather large sweep. At WOT I see a sweep from 12.3-13.0 on my new tune. Old tune it would hold a consistent 12.2-12.7.

Is it mounted at the correct position? how old is the sensor?

[TheFlyingBananaSS]

Mine sweeps too but not that extreme at WOT. My guess is the fuel tables in the tune need tweeking.

[demonspeed]

Interestingly, mine was always sweeping like you mention with my old engine. It was also mounted post-cat which is not ideal. With the new engine I added a bung in the collector so it’s now next to the leading O2 sensor - it’s reading a dead-steady 14.7 and doesn’t sweep. No tuning has been changed from the previous build (still trying to break in before new tune).

[WVracer]

Mine has a huge sweep. At WOT I see anywhere from .88 Lambda to 1.04 Lambda. I mounted the bung in the offroad connector which have the same shape as a cat. So, this could be a mixture of two problems. 1. Mine tune is still not right, but it has been getting email tuned since January and will hopefully be right soon. 2. Since the bung is mounted in the larger diameter section of the offroad pipe it might be causing some reading issues.

[Nate2SS]

Thanks all, the sensor is less than 24 hours old. I just got it replaced through AEM. The car is a cam only too. I’ll mount the gauge and record some of what it’s doing and post here for others to give more advice.

[Nate2SS]

Here’s some videos that you guys can check out and see what it’s doing. My next option is to check again for exhaust leaks and vacuum leaks.

https://youtube.com/shorts/oG4pVodYPlk?feature=share

https://youtube.com/shorts/8dHino_hHbU?feature=share

https://youtube.com/shorts/q1MNOHMHPEs?feature=share

[TheFlyingBananaSS]

It's normal for it to go lean after you take your foot out of it. Yours seems to go much further than mine though.

The idle looks a bit on the lean side and again it sweeps a lot more than mine does at idle.

I would bet barring no leaks or bad parts, it's tune related.

[CamaroDreams76]

Originally Posted by Nate2SS

Here’s some videos that you guys can check out and see what it’s doing. My next option is to check again for exhaust leaks and vacuum leaks.

https://youtube.com/shorts/oG4pVodYPlk?feature=share

https://youtube.com/shorts/8dHino_hHbU?feature=share

https://youtube.com/shorts/q1MNOHMHPEs?feature=share

The daily driving and idle seem fine. Idle I'd say mine sweeps way more than that. As far as WOT goes, thats a far sweep. I saw 11.9 at one point to 13.0.

Where is the wideband sensor and is the bung and all at the proper angle? It is a possibility that its the tune

[Nate2SS]

The wideband is welded right at the end of the long tube. The angle seems to be right. regarding the WOT, would you say a vacuum leak would cause this and not impact the regular driving and idle? I guess cause the leak would be lower given the RPM.

I'll send the videos to the tuner and see what he has to say.

[demonspeed]

From my understanding, the angle is only to ensure condensation doesn’t accumulate. Anywhere from 91* to 180* is fine for bung positioning.[/beavis&buttheadlaugh]

[Nate2SS]

Originally Posted by demonspeed

From my understanding, the angle is only to ensure condensation doesn’t accumulate. Anywhere from 91* to 180* is fine for bung positioning.[/beavis&buttheadlaugh]

Bingo, the bung is welded at a big enough angle that I don’t have to worry. I had a defective sensor out of the box but since replacing it’s been operating, numbers are just off