Me and my AEM, part 1 – by Carl Rydquist
This is the first segment of the AEM write-ups that I will be doing this year. AEM engine management systems have a lot of nice features that I have yet to tap into fully and as my Formula Drift season continues on and I get to explore and utilize more of the power within the AEM Series 2 EMS that I am using, I will add write-ups here.
Photo: D. Karey
1. Choosing the right engine management system
Building a drift car or race car is fun but it also involves a lot of decisions and challenges. The key, at least in my opinion, is to set a high target early, in terms of what performance the car is supposed to deliver. Set it too low and you will find yourself doing tedious re-work down the road once you are ready for the next step and the lower cost parts you first went with will now have to be replaced by upgraded parts and suddenly you are roughly “1,5 purchase“ into a solution instead of doing it right from the beginning and going for the good stuff from the get go. Loosely comparing this to the OEM world, this way if thinking is called “first time right” and FTR is something everyone strives for on a daily basis and tons of time and processes are put in place to create robust and people independent results , simply because re-work is the most expensive form of development.
So going for the good stuff from the outset was the reason I finally decided to go with AEM. I have to admit that I was very deeply into research of different solutions, simply because some options on the surface seemed to initially be able to cut some time in the build process, and time is money right? But in the end it was in the details and I consulted some very talented people, studied up and double checked everything from processor capacity and tune table resolution of the systems I was looking at, because in the end, I am an engineer and good or bad, I like to connect statements with data before I decide.
The AEM Tuner software is very user friendly and divided into tabs for fuel maps, ignition maps, actuators, sensors, etc.
The REAL technical advantage is what I wanted in the long run. That means not being swayed by how easy a reasonably technical person can possibly set an ECU solution up by herself/himself for the first time to run a motor on idle, but the hard facts such as how well the ECU will actually perform and manage my engine under high stress conditions, when it really matters. This is what made me choose AEM. I wanted the most flexibility and serious processing power combined with high resolution tuning tables. Doesn’t hurt either that the AEM Series 2 also has a built in boost controller! First Time Right, remember?
The boost from the Garrett turbo is controlled by the AEM S2, no external boost controller necessary. Photo: D. Karey
The project car I had bought had some positives, and some drawbacks. Positive was that it was already gutted and minimalistic in the wiring department, making life less confusing and less restricting than a full OEM harness. Basically a rolling shell. The negative was… well there was essentially no wiring, or actually, the wiring left in the shell was not useful to me. It was old and taped, and re-taped, and grimy with oil and a couple of years worth of shop dust, and it was hard to imagine that it would work reliably under “hot conditions”. So the harness had to go. No harness means blank canvas. Also means that a lot of great, well proven OEM features and diagnostics were gone with it...
Lucky for me and other people in my position, the AEM Series 2 Engine Management System is able to provide extremely useful features that can substitute much of the OEM useful on board diagnostics. This stuff is so important, and interesting that it will get its own complete chapter (3).
2. Making it work
Without any harness to talk about, the AEM Series 2 would have to be the main brain of my car, meaning no piggyback solution off of the stock ECU. To make the Series 2 run standalone is a different procedure for every car, the newer the car the more adjustments will usually have to be done, because OEMs use elaborate and very brilliant systems that often are built with redundancies and that are constantly monitored by plausibility checks. If these sytems are interrupted, they will either not work, or will throw fits such as limp home mode, or only work partially.
The VQ35DE is pretty straightforward though and one of the few things to change was that on the VQ35DE the electronic throttle body had to be converted to a cable throttle body, not because AEM doesn't handle drive by wire throttle body control, it has just not been implemented into the S2 for the VQ35DE. The AEM Infinity Series however can by now control dual Drive By Wire throttle bodies though – development moves along quickly!).
One downside for me to not have electronic throttle body control is that you cannot do like some OEMs do on their modern turbo cars, close the throttle automatically in case of overboost etc, but luckily there are options in the AEM Series 2 that can help prevent overboost in different ways (such as ignition cut at a specific, user chosen boost value).
Another example when running fully standalone was modification to the peculiar camshaft teeth on the VQ35DE, in order to make use of the variable cam timing feature in the AEM S2. Modifying the cam teeth was a small price to pay though for the significant advantage of having active and working variable cam timing (another note here, AEM Infinity has been further developed for the VQ35DE application and is now able to handle variable cam timing without modification of the cams).
Wiring wise, in theory this is a pretty straightforward with the OEM ECU is gone. The circuit diagram for the AEM Series 2 EMS is easy to read and essentially you plug in ground, 12V feed, all the sensors you plan to use, each to their channel/pin and then add your boost solenoid and you are pretty much ready to start working on the calibration and fire up, tune and go. In reality it takes patience, patience, a lot of checking and double checking, and more patience, and knowledge. It is very wise to consult an expert for these types of jobs, because an expert has seen it all before, knows what needs to be done, and will get it done.
Mitch Pederson / MP Tuning applying his science on the Rydquist Racing Nissan 350Z. It is a huge boost for anyone to hire an expert for making it all play together.
In my first step, and here I am looking at wiring rework… I had an engine that already had a factory engine harness on it. Easy enough with everything already connected, just plug in and go, right? Well I can tell you that probably there are less than 10 wires out of 50 that are left stock. Everything else we have had to change, from air intake sensor, adding boost solenoid instead of throttle body control, re-wired crank and cam sensors, injector connectors are different… the list goes on. Not because of the AEM S2 but because I use different injectors and sensors than OEM. So essentially, learn from me here and do what I pushed off, have someone build a proper harness. My plan was, still is, to get a proper harness built when I pull this engine out and install a seriously built engine. But had I had the chance to do it again, I would have had a full on proper harness built already, even for this first mildly tuned engine I am using at this moment.
At the (former) SR Tuning dyno, hearing it really sing for the first time.
Old harness or not, in my case Mitch Pederson/MP Tuning set my AEM ECU up in literally no time, and whenever there was a challenge with a bad sensor signal or something like a generator that wasn’t charging, he knew what needed to be re-wired or altered to get to the right results, immediately. Without MP Tuning, I would not have made it to Formula Drift Long Beach.
Before going into diagnostics, a short note about the datalogging capabilities of the AEM Series 2. I can't go too deep into this yet since I haven’t had it for long enough, and basically in the AEM Series 2 it’s only really intended for engine management and calibration, rather than datalogging as it is known in road racing. Still, the AEM S2 has a 1Mb memory which when you are only storing columns of data, is actually quite a bit and if you choose reasonable sample rates you can actually log for quite a long time (20-30 min is no problem and this covers most session lengths).
The really helpful features though when being at the track and having a potential problem is the ability to use the AEM Tuner software with the laptop hooked up to the ECU and being able to run through a series of checks of everything and eliminate potential issues step by step until the problem is narrowed down.
All sensor windows under one tab, and the curves can be aligned/calibrated depending on the sensor output curve, allowing perfect matching between sensor and used values (visual or internal).
I’m going to offer some candid insight here, I had a bit of a challenge right around tech time just before Formula Drift Long Beach because we had done some heavy work on the car leading up to the event and we had missed a very basic item when putting the car back together – this stuff easily happens by the way when several people work on several things on the car at the same time, and you grind through the night until early morning.
So the car was in the FD garage at Long Beach and it wouldn’t fire up. It had fired up when loading, it fired up loading off, and I had had no less than three test days without any issue to start the engine. But when trying to start for our turn on the Tech ramp it refused to fire up. “Dentist scare symptom?”
I plugged in the laptop and launched the AEM Tuner software and started from the ground up to look at the basics. I had seen Mitch go through this routine before the first fire up, but obviously I wasn’t able to remember each and every detail of it. I got him on the phone and he filled in the gaps and walked me through some pretty cool custom output setups in order to cover all the bases. One specific example was that I could control one injector at a time via the gas pedal to hear each one open and close to make sure they weren’t stuck – tech nerdy all the way but oh so cool when you are in a time crunch and have a professional drift event right about to happen. This is just one little example, out of hundreds of cool trigger/actuator combinations that can be programmed via the AEM Tuner software - many of which can be set as failsafe or performance optimizers when certain conditions are met.
Photo: D. Karey
In the end we were able to establish that there were no issues with coils or spark, no issues with crank and cam sensors, no issue with fuel pressure or plenum or intake air temp or throttle position sensors, no issues with injectors, and nothing else noticeable in the ECU. Leaving what? Had to be something substantial. Like a missing ground cable. Getting under the hood for the 10th time, I found one end of the engine ground cable harness not attached. It sat close to the frame rail but wasn’t bolted on. It had moved off the rail when the car came off the trailer which is why it would not restart. I bolted the ground wire back onto the frame rail and the car fired up instantly. A missing ground is a truly basic mistake, but as I said, 5am in the morning after 10 straight hours of hard work with many different pairs of hands on the car, those things do happen.
I sleep a lot better these days knowing that with the AEM Tuner software I can simply go sit in the Sparco seat of my racecar with a laptop connected to the AEM S2, and then I can run a 10-15 minute diagnose to check if my Engine Management System is truly happy and that all conditions are met to fire up the engine, or if there is a specific wiring or sensor issue causing a no-start condition.
This is how happy I am to be able to trouble shoot my car through the AEM S2.
Once you get the hang of these kinds of basics of advanced engine management systems such as the AEM Series 2, complexity transforms into simplicity, and you are more likely to be on the starting line on time than not.