What is an Engine Management System?   And Engine Management System (EMS) is a computerized device which manages all aspects of an engine, the fuel, ignition timing, everything.  It typically replaces a vehicle's factory ECU and require a custom installation and specialized tuning.

Why would I want an EMS?   Many reasons, actually.  For one, it allows complete programmable control of all parameters regarding fuel and ignition.  With it, you can completely control your air/fuel ratios and ignition spark advance across all possible combination of rpm and boost levels.  It also allows custom tailoring of fuel-enrichment maps for air and engine temps, as well as a slew of other parameters.  It can automatically control your boost level, control nitrous activation and deactivation, illuminate a shift light at a particular rpm, and much much more.

Why did I select an Autronic EMS?    Because my first EMS, a Haltech E6K, turned into a lemon.  Because I had already ripped out my factory G-Force-modified ECU, HKS VPC and GCC combo.  Because I had installed a custom fuel rail and 720 cc/min injectors.  Clearly, I was past the point of returning to a factory ECU.  I considered a Motec system, but the costs were substantially more than an Autronic system, and I didn't know anyone already using a Motec on a 3S-GTE in either a MR2 or a Celica All-Trac/GT-Four.  I did, however, know of a fellow in Barbados, Dennis, who is running an Autronic on his Celica GT-Four and had offered assistance in helping me with advice on tuning and installation.  So, given all the options, I selected the Autronic SMC.

Why did I buy the Autronic Exhaust Gas Analyzer?    Although the Exhaust Gas Analyzer (EGA) and Bosch wide-band (w/b) O2 sensor effectively doubled the price tag of the entire SMC system, I had several reasons to buy these additional parts rather than simply have someone else tune the car for me.

• I like to learn, and knowing precisely what the heck is going on with my engine is everything to me.  I spent about $8000 building my JUN-stroked 3S-GTE engine, and I don't plan to mindlessly destroy it by failing to paying attention to everything in minute detail.  Nor am I willing to put this responsibility on someone else.  It's my car and my engine, so I'll tune the darn thing.  Besides, I plan on making continuous changes to the car and this will undoubtedly require additional tuning after each change, as is necessary with all speed-density systems. 
• You can't tune air/fuel ratios (AFRs) on a turbo car with an ordinary narrow-band (n/b) O2 and any of those aftermarket AFR gauges.  Sorry for the bad news, but the added heat under boost will distort the sensor's output and yield false readings.  Besides, typical n/b sensors can only detect AFRs of 14.5:1 to 15.1:1. While I have no intention of looking past 15.1:1, I  want fine resolution down to 11.5:1. a w/b O2 with a EGA can do that.  In fact, the Autronic EGA and Bosch w/b sensor can report AFRs between 10:1 and 36:1.
• I can afford it.  My intent is to use the EGA and w/b sensor on others' cars, for a fee, of course.  So far, that has not materialized, but than I have yet to make it available.  As for loaning/renting it to people on the Internet, I'm a bit hesitant about that because it's so difficult, at times, to accurately identify quality from the scurge.  So, unless I know you personally, please don't waste time asking if you can borrow/rent it.

If you plan to buy an EMS, I strongly suggest buying your own EGA and w/b sensor so that you may continually refine the fuel and ignition maps to your liking.  It's one thing to tune a car on a dyno for max HP at WOT.  After tuning my car for a month or so, I'd consider that to be pretty easy compared to tuning for drivability.   And since most street cars spend 95% of their operational lifetime at loads other than WOT, tuning the maps for good drivability is critical.  I also plan to create custom fuel and ignition maps for both pump and race gas, although I have yet to go down this road.  

Finally, getting the car running and in a decent state of tune is simple and straight-forward. However, keep in mind the 80/20 rule which says that 80% of the work is in the last 20% of the tuning.  So, my point is that the EGA would not go to waste.

Do not assume you can use other wide-band O2 sensors & displays to feed the SMC without a lot of custom circuitry.  The EGA is matched to the SMC for perfect operation.  Using some other wide-band setup, and you're on your own.

Here are the most commonly asked questions regarding aftermarket engine management systems.  Please feel free to email me should you have questions not answered in this FAQ.   Otherwise, enjoy!

What is needed to tune the EMS?   You will need a laptop with a functional rs232 serial port and cable, along with an exhaust gas analyzer and a wide-band O2 sensor.  Lacking those, you should take your car a shop with dyno and familiar with tuning an EMS.

How difficult is the install?   Overall, it's not a difficult installation for someone that is experienced with general electronics, wiring systems and the use of a soldering iron.  If you have a good general working knowledge of electronics and are competent with a soldering iron, you can install an aftermarket EMS.

Is any fabrication required?   Yes.  For one, the air temp probe must be mounted in a fashion where the tip of the probe is in the direct air-stream of the post-IC air-charge.  And, you'll likely need to fabricate mounts for the unit itself.

What tools are needed for installation?   First and foremost, a factory Toyota wiring manual with the pertinent diagrams for YOUR car.  Without that, you're SOL.   Basic hand tools needed would include screwdrivers, wrenches, a soldering iron, and a wire cutter / wire stripper.  You'll also need either a flat bastard file and a lot of patience, or a dremel.

What other items are needed for installation?   For a clean installation, you will need a supply of electrical tape, an assortment of tie-wraps, solder, and wiring looms, all of which can be purchased inexpensively from online catalog giant JC Whitney.  They offer colored electrical tape and wiring looms which is what I used.  I recommend buying a stock of various sizes of wiring loom.  I bought 25' lengths of 1/4", 3/8", 1/2", 5/8" 3/4" and 1".  Expect to use a lot of the small size loom and lesser amounts of the larger-sized looms.

How many hours does the installation require?    This largely depends upon your skill level with a soldering iron and knowledge of basic electronics.  I expect the average person to spend 8 - 12 hours for the install, although other factors can influence the length of time required.  Of course, YMMV.  

Will the Autronic SMC work with my factory sensors?   Yes.  It will interface directly with the factory Toyota throttle-position, water temp and O2 sensors.

Does the Autronic operate the stock Toyota Idle Speed Control (ISC)?    No.  Aftermarket EMSs drive only two-wire ISCs, and Toyota uses a three-wire unit.  I have an ISC from a BMW that I plan to install.

That's all for now.  As people ask me questions about the system, 
I'll update the FAQ with their questions and my response.

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