Project E46 M3: Part 6 – AEM Infinity Plug and Play EMS


The AEM Infinity also uses volumetric efficiency (VE) for quicker and more effective tuning.  Basically, if you know your airflow, injector size and desired air-to-fuel (AFR) ratio, the computer instantly does the rest.  This is huge because it takes the guesswork out of fuel corrections and keeps everything working optimal. 

As a result, you ultimately can pay your tuner less because of the saved time on the dyno, as opposed to when tuning is performed using a pulse-width mapping EMS.  As an example, let's say you decide to install larger injectors.  Since the VE hasn't changed, all you have to do is input the injector size in the setup.  A little further mapping may be needed but the car will start and run smoothly.  The AEM Infinity will also control cam timing, which is crucial when trying to get the most out of an E46 M3.


The AEM Infinity EMS’ hardware is weather proofed with IP67 weatherproof connectors and sealed so you can mount it virtually anywhere in the car.  Notice the weather proofing cap on the USB connection.

I remember, back in 2004, being fortunate enough to reportedly having the second BMW E36 M3 running an AEM EMS.  But this meant that, without a plug-and-play harness, all pins had to be hard-wired—quite a lengthy process.  With the AEM Infinity, Toyota Supra MKIV and BMW E46 M3 owners are the fortunate bunch that got serviced early with an optional plug-and-play harness to get the system up and running quickly.

AEM has also released its Infinity plug-and-play harness for the Nissan 350Z and G35, featuring full control over all four cams.  AEM is currently working on releasing several more harnesses this year, including for OBDI and OBDII Hondas, LS engines, and other makes I'm not free to mention yet.


A Plug-and-Play ECU harness connects the AEM Infinity to the specific car.  Thus, the pins look exactly like those of your removed factory ECU.  Released in August of 2013, we got our PnP harness in October and yet, according to our part number, we were already #21 down the list of E46 M3 plug-and-players.  Apparently the harness—and the Infinity EMS—has been selling very well. 

The idea behind a plug-and-play harness is—you’ve guessed it—to make installation take minutes instead of days. The AEM Infinity plug-and-play harness also has an auxiliary port to simplify the wiring of any other ancillary sensors.


Here is the original S54 ECU pulled from the car.  Notice the identical pin alignment to the plug-and-play adapter.  You can also see the corrosion that led to this ECU's demise.  The 24-pin connector, second from left, has a pin for the DME relay second from the top-right corner (where it's copper in color).  That's the one that broke in September so thank goodness for AEM's timely release of the S54 Plug-and-play harness just a month prior!

When it was all said and done, this was almost everything we ordered for Project E46 M3, including the EMS, Plug-and-play harness, Manifold Air Pressure (MAP) sensor, dual wideband oxygen sensors, and oxygen sensor harness extensions (not pictured).

Since the AEM Infinity is capable of working with flex-fuel sensors, we’re also planning on potentially tuning the car on ethanol E85 pump fuel.  However, AEM doesn’t carry the flex-fuel senor as of late, so we’ll just need to order one separately.

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