AEM Wideband UEGO A/F Ratio....what should it read?

[s14_sport]

Ok so I got AEM wideband installed last week. I know its supposed to read below 12s at WOT. But does it matter what it reads at other times? Like at idle its super lean 15-16-17 and sometimes off the charts. I heard it only matters what it reads at WOT so I just want to make sure.

Also I had the Apexi PFC installed and the A/Fs were all over the place. Even at WOT it wasn't steady. I have reset the PFC and went through the idle learn process a couple of times and it read the same. would go from like 12-13 somtimes 14 at WOT! Then I put the stock ECU back on and its back to normal. around ~11.5 at WOT. I'm sticking with the stock ECU for now.

[Largekid]

Ok so I got AEM wideband installed last week. I know its supposed to read below 12s at WOT. But does it matter what it reads at other times? Like at idle its super lean 15-16-17 and sometimes off the charts. I heard it only matters what it reads at WOT so I just want to make sure.

Also I had the Apexi PFC installed and the A/Fs were all over the place. Even at WOT it wasn't steady. I have reset the PFC and went through the idle learn process a couple of times and it read the same. would go from like 12-13 somtimes 14 at WOT! Then I put the stock ECU back on and its back to normal. around ~11.5 at WOT. I'm sticking with the stock ECU for now.

Ok, lets start at the top.

Under 12 at WOT is fine...during cruising you should be close to 14.7, I never see anything over 15-15.1ish. The only time the A/F should read out the lean end is when you let off of throttle, like when coming to the stop. A/F's matter everywhere...just they are more important under boost though.

As Far as the PFC, no matter how many times you reset the PFC, or have it relearn the idle, it will still run like crap till you get it tuned. It runs very different than a stock ECU. When you plug everything in, and get it all ru ning...you would have to go in and adjust the tables to compensate for the new maps etx.

[s14_sport]

I have been told numerous times by very reputable people that the PFC has a conservative tune straight out of the box. That with mods it will need to get tuned, but, with a nearly stock motor you should be fine.

But to me the A/F ratios I'm seeing at WOT with the PFC thats certainly not conservative, more like dangerous. So I put the thing back in its box and replaced with stock ecu for now.

[Darius]

How sure are you that there are no exhaust leaks between the head and wideband sensor? Any leak will introduce air into the exhaust and make it "look" like the engine is running lean.

17 is pretty high at idle. I'm surprised it doesn't start to fall on its face at that point.

[s14_sport]

I do have an exhaust leak....i have a broken bolt on the exhaust manifold...

[Darius]

There ya go. At least you know the wideband is working! Your engine is probably running rich since the stock O2 sensor is reading that air too and trying to compensate for it. There's your safety factor right there

[WhatsADSM]

Keep the PFC out until you get a tune.

Sounds to me like the wideband is working just fine. If you are seeing 11.5 A/Fs with the stock ECU and way over that with the PFC then its not a wideband issue it's a tune issue.

As for the idle... what does it idle around with the stock ECU in?

[s14_sport]

A/F at idle floats around 15-17+ with stock ECU

[240z4u]

A/F at idle floats around 15-17+ with stock ECU

Your wideband is giving you some false info. My car idles horribly at those a/f ratios. Sputters and stumbles.

Evan

[Darius]

It isn't truly seeing 15-17 AFR in the combustion. The wideband is seeing air leaking into the exhaust upstream of it. Like I said before, it is actually running rich because of the exhaust leak upstream of the stock O2 sensor. No need to worry about the PFC and its conservative fuel map. Not going to hurt anything without a tune unless you're thrashing it at or near redline. Just not going to be as fast as it possibly could.

[Coolwhip]

mine cuts out and dies if at 16+

[Carl H]

or it could be that the aem uego is trash.even with a *minor* exhaust leak at the manifold mine still idles round 13.3-13.5:1 where i tuned it to...i say either bad sensor (very possible with the uego), bad placement, or horrendous exhaust leak.

[craz4240]

or it could be that the aem uego is trash.even with a *minor* exhaust leak at the manifold mine still idles round 13.3-13.5:1 where i tuned it to...i say either bad sensor (very possible with the uego), bad placement, or horrendous exhaust leak.

Since I have since corrected these issues on Carls advice on my car i would listen to him.

[s14_sport]

my friend has an SR with the same uego and i looked at his just to compare and at idle he's off the charts...17+ not until he gets on it does the A/F ratio act normal

[Darius]

There are too many variables to compare to your friend's car and what it idles at. The ONLY similarity is that you have the same WB. Fix the broken exhaust stud and see if that helps change the reading to something more accurate.

[TSL]

What engines and mods are we talking about?

[l0nestar]

There are too many variables to compare to your friend's car and what it idles at. The ONLY similarity is that you have the same WB. Fix the broken exhaust stud and see if that helps change the reading to something more accurate.

+5

Fix your exhaust studThrow the UEGO in the trashPick up an Innovate LC-1 and install

[neonbomb]

Widebands are only as accurate as their sensors.