S6 AAN EMU Black voltage drop issues

[vlads4]

Hello everyone,

Got an Audi urs6 (2.2 AAN), switched from stock ECU to standalone EMU Black.

Basically, I still can't figure out the voltage drop I get while turning on anything electrical in the car (headlights or heater for example).

If I turn on the low beam or high beam, my lambda goes a bit rich, and my tacho won't go above 5000 rpm and working erratically although in EMU software I can see it going 7000+ rpm just fine. Turning the heater on or the lights would make it run even richer.

EMU Black would record a small voltage drop 0.3-0.5 if I turn anything on, but I'm pretty sure it's different to what it actually is, I will take a measurement directly at the injectors and update the post.

I have used the stock wiring, just made a PnP adapter for the EMU.

The measures I've taken so far:

I have triple checked all the grounds on the car

Removed the dashboard, fully disassembled and made sure I have no issues with it

I checked the voltage drop on the alternator and on the battery, again it's just fine (0.2-0.5v, when turning on the heater or lights)

The injectors are calibrated properly so even if there's a voltage drop they should compensate just fine.

I did not have any issues like this on stock Motronic ECU.

I think that the fact that it goes richer and tacho works erratically is somehow linked.

Before switching to Standalone (EMU Black) I did the following mods with the car:

1. Converted from automatic to manual transmission
2. Switched to the TFSI coils (as per schematics on the internet, tested 2 different harnesses as to exclude this as an issue)
3. Made sure that all my power grounds do not link with sensor grounds

Any ideas?
Could this be a bad ground somewhere, an old relay that's giving me this headeche?

What relays I could check, or maybe you could point me in the right direction?

[Error404]

Sounds like you joined the sensor ground to the chassis ground - this creates a voltage offset. Sensor ground must ALWAYS be grounded at the ECU sensor ground terminal - you should check this
HTH
Alex

[vlads4]

Sounds like you joined the sensor ground to the chassis ground - this creates a voltage offset. Sensor ground must ALWAYS be grounded at the ECU sensor ground terminal - you should check this
HTH
Alex

Thanks Alex for trying to help.

I started to check if there's indeed no link in my wiring between Power Ground and Sensor ground.

Basically I have an oil pressure sensor that i've installed myself (5v , analog input, sensor gnd), so I used it to check if there's a link between sensor gnd and power gnd.

I tested for continuity between sensor gnd and engine block, and there's indeed a connection between them, with nearly 0 Ohm resistance.
So I started to check all the grounds again, spent like an hour to make sure that I did not mess up with my PnP adaptor and can confirm that there's no issues I can see with the wiring. Sensor gnds and Power gnds are separated.

Okay, next there's a funny thing, I became curious maybe it's the ECU that makes fun of me, so I checked for continuity the pins on the ECU between Sensor gnd's and Power gnd and finally Sensor gnd and ECU Gnd.

No link between Sensor Gnd and Power gnd , however there IS continuity between ECU GND and Sensor GND (I am not 100% sure if this is how it is supposed to be).

Although I followed the instructions on the Ecumaster website, where there is clear instruction on what and where to connect specifically for my engine, I can assume that there should not be any continuity between ECU GND (which is connected to the chassis or engine) and Sensor GND.

After unplugging the ECU I did the continuity test again between a sensor GND and Engine block, and there is NOT any continuity.

I am super confused now and really want to clarify if the grounds are right first before diving deep into the voltage drop.

Finally, I do not know how important this is, but I can not test output my injectors when the ignition is switched on, as I have disconnected Pin 37 from the main harness which feeds the holding relay that consequently provides 12v to the injectors when the ignition is on. Car starts and runs fine otherwise, but I have disconnected it as I could not turn off the car from the key, as soon as I disconnected pin 37 from the 12V feed, car starts and stops fine from the key.

Thanks everyone.