Where to tap power and ground for AEM UNGO wideband gauge?

[MarkIII4Me]

So I ran the power from the cigarette lighter and the ground from a brown wire that runs to the left of the shifter. Will this produce inaccurate readings? I've read conflicting posts. Some state to run power and ground directly from the battery, others say to run 2 grounds and others say tap the power and ground from the ecu.
And of course, some people take the power and ground from anywhere. Which is the best route? I just wired the white 0-5v lambda wire into my AEM EMS and want to enable the auto-tune function to build some preliminary maps. Needless to say, I don't want to damage my engine with inaccurate readings.

What sayith you???

 

[Turbo Habanero]

I ran mine from the the power and ground from the ecu.

Never had problems with it or leaning out.

 

[shipkiller]

I used the "acc" 12V and a chassis ground. No problem, either

 

[MarkIII4Me]

When you say "Chassis Ground" do you mean the ones at the ECU from plug A? If so, which one do you tap into as there are 3 of them. Currently I tapped into Chassis Ground 26A. Should this be fine? I spoke with someone at AEM on the phone today and he said not to use a chassis ground from the computer as it can cause noise in many of the factory sensors. But there's a separate sensor ground on plug B. So any of the chassis grounds from plug A should be fine to tap into, right?

 

[scottiedawg66]

I usually just ground right into the chassis. I usually use the cigarette lighter power source to pull power for gauges rather than the ECU. I would hate to have an ECU issue related to taping into the 12V source. It might be fine but I am not a professional, so I have always used the cigarette lighter power.

 

[hvyman]

I ran mine to the turbo timer harness and ground to chassis.

 

[Enraged]

if you are using the stock ecu, it probably won't make a difference. If you run a standalone, I know that my AEM manual states to ground the gauge at the ECU.

 

[MarkIII4Me]

Where in the manual does it say that? I read it several places on the aem forums that members were getting more accurate readings in Pro Tuner by running power and ground to the ecu. The aem guy told me today that he does not advise sharing a ground since the controller can pull a decent amount of current when warming up the O2 sensor.

I just want to be sure that I can leave my UNGO WB grounded at ECU PIN A26 so I can finally put my glovebox back in. It's been out with a mess of wires and the ems dangling for over a year now. I want to be done with this already and head back to the dyno.

 

[jg5899]

I grabbed power from acc and a ground at the chassis and am currently having an issue where the wideband reading displays different than the analog output. This is on a brand new unit with 0 miles on it. Going to tap into the ecu power and sensor ground to see if there's change tomorrow.

 

[MarkIII4Me]

I would not use the sensor ground in plug B as that would almost certainly cause noise in the signal of your other sensors. If your going to power the gauge off of your ems, use the the Ignition Switch for power (pin 2D) and a chassis ground (either pin 13A, 14A or 26A)

 

[Enraged]

Page 53 of the AEM EMS User Guide V2.0 says to attach the Sensor Ground to the ECU, but the AEM UEGO that I have only has one ground, so we attached it to the ECU ground. No issues with it like that so far, but MarkIII4Me is right, it could cause noise. If it gives me issues I'll move the ground.

 

[MarkIII4Me]

Was on the phone with AEM again today, (this time because AEMPro wasn't showing HS1 as an option under output configuration, turns out it is dedicated for auto trans torque converter control so guess I'll be using a different HS output for fan control). Anyways, I asked again about the UNGO power and ground connections. I was told that running them to the ECU is stupid and can only cause problems. Fine tune the sensor in AEMPro by adjusting the gain. Nothing more. So that does it, I'm once again moving my power and ground connections for the WB gauge to a dedicated circuit. I'll probably connect them to where the ECT button was plugged in. There's an open power and ground there. Then I'll measure the 0-5v Lambda signal at LAMDA 1 (Pin 6B) with the O2 sensor unplugged to get my base voltage reference and tune the gain in AEMPro to match. With the O2 gauge's power and ground ran to the ECU I was getting a reading of 2.4v, so I'm curious to see what I'll get after I relocate the power and ground.

I was really trying to keep everything the way it is, but better safe than sorry. True I was getting a rock steady 2.4v at pin 6B, but who knows what kind of fluctuations would be present in the readings once the ECU is connected and drawing power. Once I discovered how limited the wideband knock control is in the V1 (unsure if there were improvements in mine since it was the last version to leave AEM for our application, [AEM v1 Rev.B Mod.C]), I'm not as concerned as I previously was about dead on accuracy of the WB readings anymore. In retrospect, if I was, I probably shouldn't be using and UNGO to begin with.

 

[Enraged]

Well thanks for checking, my dash is out right now and I'm fixing wiring, so I'll move mine over to their own dedicated connections. I was planning to run dedicated power/ground from my battery in the hatch anyways, so one more circuit won't be much work.