EFIDynoTuning Forum

A while ago, I bricked my AEM 30-4110 and am now replacing it with an AEM 30-300 X-Series.

Along with the Analog Sensor 0-5V input (going to pin 27 on the EEC-IV), the new unit includes an Analog Sensor Ground wire.

Should this ground wire be connected anywhere?

the 4110 is far superior to the 300 as its the only wideband under $1,000 thats comparable to a lab spec wideband. Its specifically stated in the pre tune write up.

You can ground the ground if you want but it shouldnt be needed.

Appreciated.

The 30-300x has a differential analog out (4110 does not) implying some level of isolation from power ground internally. The aem analog brown should be connected to EEC sensor ground pin 46 when analog white is using EEC pin 27.

Not doing so introduces ground offsets to the hego signal that will skew readings.

The aem instructions explain the connections.

Thanks, jsa. That makes sense. Pin 46 it is for the ground.

negative

pin 46 is a ground output not an input

you should not introduce another ground output on 46

its unlikely but possible you could offset that ground causing all 5v signals to be skewed

I partly agree to disagree for reasons as follows.

Pin 46 is the EEC sensor ground for many sensor pins including pin 27 in this case.

Measurement of EEC sensor ground to EEC power ground usually reveals a voltage offset with just the OEM sensors connected. Not connecting the AEM 30-300x brown sensor ground to EEC pin 46 will ensure the HEGO sensor signal on EEC pin 27 is offset by the EEC ground offset.

The whole point of differential sensor outputs, is that they equalise to the input ground rail without offsetting it.

I run the inline version of the 30-300 which has the same output signals and have found it does not introduce any further ground issues. YMMV subject proper wiring practice.

Poor wiring practice could introduce noise and offsets on both the signal and ground. Measure before and after to confirm installation practice is good.

One advantage of the 30-0300 series is the serial data out. Error can't be introduced on that by output signal noise, ground offsets or ADC error, as it's digital. The serial signal can't be logged while using a QH when using TP because TP only logs one datastream. On the other hand BE can log multiple datastreams and has AEM support, but for a fee. It's also possible to view the serial signal values in a serial console like Termite or whatever you prefer, but that is not in the log file with everything else included.