AEM UEGO Controller

**1ViciousGSX** · 01-29-2005

Well I finally got my AEM UEGO controller package and add-on gauage installed a couple of days ago. I hooked the 1.0-5.0v output to the rear O2 sensor input of my ECU (DSMLink will log it) and the 0.0-1.0v output to the front O2 sensor input at the ECU in place of the stock O2 sensor. Pretty simple installation. That's the good news.

Bad news. It only took me a couple of minutes drive time to figure out it won't work this way. The car started fine & idled fine (lean @ 16.5-17.5:1 a/f ratio). But trying to drive it was another story. Once I started driving the car the ECU started to go lean very quickly and very badly (19.4:1 on the UEGO) to the point were it lost all power. DSMLink was showing .40v at the front O2 sensor input and my fuel trims were going way lean. I re-checked everything to make sure it was hooked up correctly and it was. So yesterday I called AEM tech and asked them about it. They told me .40v is really lean on the low-band output. I told them I agree, but .40v is not lean for a stock style ECU as .50v is stoich (14.7:1). This is not a very good "mimic" of a stock style O2 sensor. The ECU is looking for a lower number to see lean mixtures. AEM tech didn't have an answer for me on this. I guess most people buy the UEGO controller to hook to a stand-alone system.

So today I put the stock O2 sensor back into place and had an exhaust shop weld in the add-on bung into my exhaust right after my flex-joint at the rear of the engine where I mounted the wide-band sensor. All my fuel trims lined back up correctly. The UEGO shows 14.5-15.2:1 a/f ratio while idling and cruising with the stock O2 senor controlling things. I did go up on boost also and found my WOT ratios to be 10.5-10.8:1 without me changing anything. So my fuel trims were pretty close, but now I know for sure. So now I can at least have a real-time display of my a/f ratio and log it.

So for a "heads up" to everybody, I can't say for sure if the FJO, PLX, etc. wide-bands do a better job of trying to "mimic" a stock O2, but they will need to if you are trying to do what I was trying to do. Other than that, everything is great.

Alpine TSi · 01-29-2005

Good to know, I use the PLX and have the "mimic" wiring hooked up instead of a narrowband O2, and it works fine. Glad to hear you got it to work right though, now get that thing on a dyno and do some tunning!

**JET** · 01-29-2005

My Techedge also has .50 as 14.7:1

**scheides** · 01-30-2005

Quote:

Originally Posted by Alpine TSi

Good to know, I use the PLX and have the "mimic" wiring hooked up instead of a narrowband O2, and it works fine. Glad to hear you got it to work right though, now get that thing on a dyno and do some tunning!

So you just have the PLX running on its own, with the stock o2 sensor hooked up in its original location?

This is very interresting, does anyone know why they differ so much from the stock o2 sensor? Specifically, if the wideband o2 units use .5v as 14.7:1, what voltage does the stock sensor use?

Alpine TSi · 01-30-2005

Quote:

Originally Posted by scheides

So you just have the PLX running on its own, with the stock o2 sensor hooked up in its original location?

This is very interresting, does anyone know why they differ so much from the stock o2 sensor? Specifically, if the wideband o2 units use .5v as 14.7:1, what voltage does the stock sensor use?

I am using the sensor that came with the PLX in the stock location, I have the narrowband output from the PLX going straight to the ECU. I just cut the wire and connected the PLX output to the ECU. Works fine.

No other O2 sensor in the car.

02-15-2005

Quote:

Originally Posted by scheides

So you just have the PLX running on its own, with the stock o2 sensor hooked up in its original location?

This is very interresting, does anyone know why they differ so much from the stock o2 sensor? Specifically, if the wideband o2 units use .5v as 14.7:1, what voltage does the stock sensor use?

Widebands use 1v-5v not 0v-1v

**JET** · 02-15-2005

Quote:

Originally Posted by DSMnUB

Widebands use 1v-5v not 0v-1v

Either you didn't read the posts or you don't know what you are talking about. We are talking about WB02's with a narrow band emulator in them. So yes, they do put out a 0-1v output.

MustGoFaster · 02-15-2005

Quote:

Originally Posted by Alpine TSi

I am using the sensor that came with the PLX in the stock location, I have the narrowband output from the PLX going straight to the ECU. I just cut the wire and connected the PLX output to the ECU. Works fine.

No other O2 sensor in the car.

Same deal for me too. It acctuly fixed my idle wondering too! (not surge)