Help get an AEM UEGO to talk to an AEM EMS

[EvDog]

I have a 95 Miata, AEM Series 1 EMS PnP, and an AEM UEGO gauge/wideband. The wideband is installed, the gauge has power and is grounded. The gauge however, is not hooked up to the EMS. This requires me to take the white wire from the UEGO and connect to the EMS Lambda input. I don't know where that is. My application notes for my EMS tell me the Lambda #1 Pin is 2N, #2 is 4J, and the Sensor GND Pin is 2C. I have no idea what this means. I'm just want the AEM UEGO to communicate with the AEM EMS. How do I make this happen? Thanks.

[—kung fu jesus—]

Evan, what year is your car again?

[—kung fu jesus—]

This should help:



Those directions are telling you to cut the wires that are going from the OEM O2 sensor a few (3-4") inches back from where they connect to the OEM ECU pigtail connector and connect the WBO2 wires to them. Obviously, you are connecting to the wires going to the connect to the ECU, not the wires going to engine bay harness.

I need the year of your car, so I can confirm the wire colors. The 94-95 don't have a "4J' pinout. The ground wire should be the same between the WBO2 and the ECU. This is the case for ANY WBO2.

[EvDog]

Okay thanks. My car is a 95. According to AEM, I have two options to connect the WB02 wire to the AEM EMS. One that is connected to one of the pig tails, and one that isn't. I wasn't sure if I should try to connect the wire to the metal prong that is not being used or splice it one of the wires in the pigtail. The latter would be more convenient so that switching from AEM to OEM would be easier; And so you say that it's cool to just splice it together a few inches back. Cool, I have it written down at home which is the correct wire i need to splice. If I get this hooked up, the next step is to figure out how to run an autotune via my laptop and figure out the "tach-drop" issue.

ps. I like that your user name now has a visual.

[—kung fu jesus—]

Thanks!

On my car, it is OBD1 and only has one O2. Yours is the same way. I clipped the wire that sends the signal from the OEM O2 about 3" back from the ECU connector and spliced in one of the two signal wires from my WBO2. The other signal wire goes to the gauge on my A pillar. My WB is an Innovate LC-1.

Remember that the OEM ECU can run on a WBO2 signal IF you set the WB settings back to narrow band.

Take your time with it, it's not too hard if you plan it out. Search miataturbo, there may be some good info in there about wiring in the AEM unit.

The dropped tach is because of the CAS or coilpack. I can't remember which your car pulls the signal from.

[EvDog]

Thanks Steve! I got it hooked up yesterday. Now I want to make sure the tune is in check. It seems mostly fine, the car runs really well at full and partial throttle. The only issues being running rich at idle (10-11:1), a high idle that takes a while to settle after slowing down(1500-2000rpm for several seconds), and going too lean when very light on the throttle at freeway speeds (16-17:1).

[—kung fu jesus—]

Is the car running on the AEM ecu? That is where you need to adjust your AFR tables and settimgs. I have never worked with an AEM, adjust at your own risk.

Does your O2 allow for a free air calibration?

[AARP]

Just replace the UEGO with this

[EvDog]

Is the car running on the AEM ecu? That is where you need to adjust your AFR tables and settimgs. I have never worked with an AEM, adjust at your own risk.

Does your O2 allow for a free air calibration?

Ya I had to plug in the AEM because the OEM was not working with the new 02 wiring. When I would try to apply throttle it would just sputter. I did not want to put the AEM in yet because I don't trust the tune on it. I put it in anyway and it ran good at the begginning of the day other than the issues I mentioned above, but in the afternoon the car would hardly start and it began to detonate at full throttle. So, I think I will disconnect the new 02 wire and plug the OEM back in. I would like to adjust a few things on my laptop, but I have no idea how to make proper adjustments. Other than AFR's and RPM's, the other numbers are meaningless to me.

[—kung fu jesus—]

The OEM ecu cannot run on a wide band signal. If the UEGO has a programmable signal, like the LC1, change the output signal to the ecu to narrowband.

You car symptoms are like mine were when I switched out the ECUs (MS back to stock) and forgot to change the O2 program back to narrowband.

Double check to make sure you wired it correctly, first.

I don't know the specifics on the AEM O2, but on the LC1, there are two signal wires. On my car (stock is a single wire O2), I can connect to the LC1's computer on my laptop and set either of the signal wires independently.