Wiring from AEM UEGO gauge to ECU

[DenisAlmos]

Hi everyone,

 

I have an Impreza GT 2000 (same as WRX6) and a G4X WRX6X ECU.

I'm also running an AEM UEGO gauge wideband and I like to connect it to my ECU.

 

Does the CAN 1/RS232 is the best solution? I didn't found the voltage of both devices for RS232 and I don't want to damage the ECU.

Or maybe the analogic 0-5V is more simple?

I've been thinking to connect the ECU directly to the sensor but I don't know if it's possible to have 2 devices riding on the same sensor. Any idea?

 

Thanks a lot

[Adamw]

What is the part number of the AEM gauge you have?  Is it an X-series?

[neo277]

Hello.   I have the older uego and not the x series so i wired it to the AN volt on the expansion connector and the ground to the ground pin on the expansion connector.

[DenisAlmos]

@Adamw,

My gauge is an 30-0300 X-series UEGO with Bosch LSU4.9

@neo277,

ok good to know the analogic connection works fine. I prefer the numeric way to do it in case some interferences disturb the values I read in the ECU.

[Adamw]

Ok, with an X-series you can connect via CAN bus.  

You will need a CANPCB cable and a CANF plug to access the CAN bus on a plug-in ECU.

Connection will look something like below - note AEM documentation uses slightly deiiferent terminology to us - they call CAN H "AEMnet+" and CAN L is "AEMnet-".

Instructions for the software set up is in the helpfile article > G4X ECU Tuning Functions > CAN > Device Specific CAN Information > AEM X-series

[DenisAlmos]

Thanks a lot @Adamw,

 

I finally connected the gauge with analogic output, but what I was afraid of happened. I don’t have the same numbers on the gauge and in the ECU.

I’ve first use the calibration saved in the ECU, when I realized the values were not correct, I created a calibration table with the scaling written on the instruction manual. Didn’t worked either. With the AEM scaling, I’ve noticed the voltage the ECU is receiving is not the voltage it is supported to receive.

For an AFR of 11.3 I'm supposed to have around 1.75V and for an AFR of 10.7 around 1.5V.

 

What I have is:

Volts	ECU AFR	Display
1.35	13.5	11.3
1.3	14.5	11.2
1	15.3	10.7

What I'm supposed to have is:

Found the full instruction manual here: https://www.aemelectronics.com/files/instructions/30-0300.pdf

[Adamw]

This is why I suggested you connect it via CAN in the first place.  But anyhow, it seems you also have the calibration set up wrong since the ECU is reading backwards compared to the signal.  Lower voltage should mean lower AFR but yours is going the opposite way.

Please attach your tune and I will take a look.

 

[DenisAlmos]

@Adamw sorry I juste realized I named the colons wrong in the previous poste. This is correct:

 

Volts	AFR Gauge	AFR ECU
1.35	13.5	11.3
1.30	14.5	11.2
1.00	15.3	10.7

But the calibration is not ok, I agree.

I'm plug it by CAN as you described previously.

 

This the tune I'm using now, It's possible I did some changes since I did the compare.

ImprezaGC8_TMT_2L+1.2bTurbo_Perso_ColdStart_IdleDev.pclx

[Adamw]

Something doesnt look right in your measured voltages above.  At 15.3AFR your gauge should output about 3.4V, that is a long way off 1.00V that you report.    

This cant be explained by a ground offset or other common analog error.  Either something is wrong with your measurements, or the gauge is faulty.

[DenisAlmos]

@Adamw,

I still can't found why the analogic doesn't work so I've looked at the CAN more on details. I saw the CAN bus needs a 120 ohms resistor at both ends.

Does the CANPCB and CANF you mention needs resistors or is it integrated in the cable?

[koracing]

Are you sure you're connecting the correct analog output wire to the ecu? 

 

I'm not sure what you would see if you connected the blue wire for example, or if you mixed up the brown and white wires.    The white wire needs to be connected to the analog + input and brown to sensor ground.  I've installed several of these gauges and never had an issue with the analog input to the ecu. 

 

Regarding your CAN connection: the Link ecu has a 120ohm resistor at it's end, and at the wideband sensor end you will need to add another near the end of the connection at the gauge.  Neither of the CANPCB cable or the CANF cable have any terminating resistors.  

[DenisAlmos]

Yes I connected the brown wire of the gauge to the brown wire of the extension loom and I connected the white wire of the gauge to the yellow of the extension loom. The pin of the yellow wire is named "temp2" but I assume it's a 0-5V input?

[koracing]

9 minutes ago, DenisAlmos said:

Yes I connected the brown wire of the gauge to the brown wire of the extension loom and I connected the white wire of the gauge to the yellow of the extension loom. The pin of the yellow wire is named "temp2" but I assume it's a 0-5V input?

You have a Link expansion harness?  The wire colors are:
1. Green
2. Red
3. Grey
4. Brown
5. White
6. Blue
7. Yellow
8. Orange

I think your WRX6X expansion connector 1 is:

 

It's not possible to set Lambda 1 input in the software to AN Temp 2 (this is not the same as AN Volt 2) - but it would be simpler to go to AN Volt 5 or 6  (ANV5 being the white wire in the expansion would be white wire to white wire).  The brown wire must go to the Green wire or Ground.

[Adamw]

1 hour ago, koracing said:

You have a Link expansion harness?  The wire colors are:
1. Green
2. Red
3. Grey
4. Brown
5. White
6. Blue
7. Yellow
8. Orange

Note the colours of the expansion harnesses have changed a few times over the years, you need to work off positions rather than colours.

 

4 hours ago, DenisAlmos said:

@Adamw,

I still can't found why the analogic doesn't work so I've looked at the CAN more on details. I saw the CAN bus needs a 120 ohms resistor at both ends.

Does the CANPCB and CANF you mention needs resistors or is it integrated in the cable?

The ecu has a termination resistor built in for one end of the bus.  You should fit a resistor at the other end close to the AEM device.

[DenisAlmos]

I've found a bit of time to check the wiring and it was faulty. I mistakenly connected the ground of the gauge to an analogic input of the ECU.

With the ground to the ground it works. The default calibration for AEM EUGO wasn't correct so I created one.

 

Thank you @Adamw,

It's probably going to help so people. Maybe I'll use the CAN bus if I have more CAN devices in the future upgrades.

 

I've already notice a lean short moment after acceleration. I can now show it to you in a log. Please found it and my actual mapping in this Google Drive: https://drive.google.com/drive/folders/12Modu01QtKC_UO-0wqdYfWSMMtq7TGtH?usp=sharing

Do you have any recommendation?

[Adamw]

Update to the latest firmware and do another log.  Accel fuel function has been improved in newer firmware.

Also, you should have 1.0 as the smallest number in your accel cold correction table.  Zero above 70°C means you will get no accel enrichment when coolant is above 70°C.

[DenisAlmos]

Thanks @Adamw,

I understood that Acceleration correction is a multiplication factor, I thought it was an additional value. Maybe it will be useful explain that it's a factor in the help section. It works much better now.

I'll have a look to update the firmware.

[Vaughan]

[DenisAlmos]

Ok @Vaughan, my mistake then