Tip: Evaluating Engine Management Solutions, Part 1

Haltech Sport 1000 ECU and custom engine harness. (Image credit: rotormaster.com.au)

UPDATE: See Part II of this series here!

Admit it. You’re someone who has the wherewithal to bastardize cars to have mo’ powwah, for no logical reason. You have  a shopping list for some serious engine hop-up parts. Your engine builder will put them in and add  his own supertuning and blueprinting tricks for more bad-assery. But as the powertrain bolted back to the body, you’d now want to get the car running, and running to its best power potential, while at the same time maintaining drivability and fuel economy. Thus, you have to consider your engine management options.

Engine Management is the management of the three elements of combustion (fuel, air, and ignition), plus other aspects like valve timing, in order to achieve optimum combustion in the engine, maintain proper idling, and to generate power for vehicle movement. An Engine Management System is the sum of engine components that allow proper engine management to take place. Every engine has some form of engine management, whether based on mechanical items (i.e. carburation), electronic (i.e. ECU), or even electromechanical (i.e. drive-by-wire throttle body). Thus, the trick to getting your modified engine to run right is to gain the ability to adjust the different components to get it purring pretty.

Personally, I have thought long and hard about engine management, and got to apply what I’ve learned to Project Elantra. Though I can’t tune an engine for the life of me, I can at least guide other lost souls towards a solution. Read on for Part I of what I think would help the enthusiast tune out the most from their engines.


Image credit: dragracingonline.com


0. Caveat

The article assumes your car has an electronically controlled engine management system from the factory. It’s hard to give recommendations other than general advice, as each application may have different needs and solutions that cannot be accurately defined in a basic guide such as this. Note that we are sponsored by a supplier and tuner of programmable ECUs (Haltech Philippines), so I may be biased with a particular tuning path.

I mention products and brands of engine management solutions in this guide. I am not recommending or dissuading the use of any equipment other than what we have had experience with. Furthermore, do not assume that they are all the stuff available in the aftermarket. You have to do further research and see what are available and what would and would not work for you. Don’t hesitate to ask around for advice. And if you think I’m wrong, please do not hesitate to hand my ass over on a silver plate by your hopefully PG-13 comments.

If you live in an area with government regulation that affects engine management (i.e. vehicle emissions laws), you better find out how not to run afoul of them. This type of modification may void your new vehicle warranty faster than castor oil voiding your bowels. And, if you blow up an engine or two, it’s not my fault.

Caveat lector.


1. Evaluate your starting point and your goals

Are you setting up an obtuse car like a J2 Hyundai Elantra? Or a mainstream (well, in the Philippines at least) tuner car like a Civic, Corolla, et.al? Or a V8 pony car? Or an Audi/Bimmer/Benz? Obviously, knowing the car you’d be playing with would define the options that you’d have at your disposal. Common tuner cars like Hondas, Nissans, or GMs may have solutions that allow you to reprogram the stock ECU. Otherwise, you may have check out other options (see steps 2 and 3).

What you plan to do to the car would also dictate your engine management needs. Are you merely improving the engine’s breathing (i.e. I/H/E mods)? Are you turbocharging an originally naturally-aspirated engine? Are you dramatically changing the internal specifications of the engine (i.e. bore or stroke up, longer duration camshafts)? Basically, the more radical the modification, the more the need for you to address engine management.

I cannot emphasize enough the importance of goal-setting if you are just starting your project. Plan properly and you will avoid over-spending for something you don’t need, or under-spending for something that is downright critical. If  right now, you are finding yourself in a hole you cannot tune yourself out off, then I guess you didn’t plan ahead.


2. Do your research

Now you know what needs to be tuned, now’s the time to do a bit of sleuthing on what can be done. Google your issue up. Ask your virtual car friends at your marque or model’s local message boards for advice. Go to a tuner near you for their thoughts and their available options and products.

At this stage of your research, you might even realize that you can do some or all of the work yourself . Read DIY’s, installation manuals, and the like if you are so inclined. Even if you end up having someone else do the install and tuning, at least you can tell him off when in the unlikely chance he’s doing something stupid to your car.


3. Consider your options

After your research, advice-gathering, chikahan, et cetera, you would see that basically there are 5 options in modifying engine management. They are as follows:  Leaving the stock ECU alone, Confusing the stock ECU, Tweaking the stock ECU with a piggyback, Retuning the stock ECU, and Deep-sixing the stock ECU with a standalone, programmable aftermarket ECU. We’ll throw in the oddball choice – converting to carburetion – just to cover all possible bases. We’re covering half of them in this Part. Stay tuned for Part II for the rest.


Mazda Miata stock ECU. Image credit: nile13 of miataturbo.net 


a. Leave the stock ECU alone

Most simple, because you ain’t doin’ nothin’ to the stock setup. Note also that the stock ECU is far superior to almost anything aftermarket. The tuning parameters programmed into the unit are the result of a load of time and a ton of effort by a pretty smart bunch of powertrain engineers. The stock setup allows for the engine to cope with environmental changes like temperature and barometric pressure for drivability in all conditions, while at the same time being squeaky clean for the smog testers and being thrifty at the pump. It is far easier to screw up than to improve upon the standard tuning.

Leaving the stock ECU alone is a viable option if you’re just going for I/H/E mods or any other mild modifications. The ECU can compensate for the minor changes brought about by these mods. If you’re adding a turbo, upping the boost of the stock turbo setup, running a wild cam, changing compression ratio, or adding displacement, then you have to do something, as the ECU would think it still is controlling a mouse instead of a monster that you made it to be. You can’t expect the boffins back in the factory knowing your need for mo’ powwah. Or your need to mess with something that’s already perfect. Whatever.


Rising Rate Fuel Pressure Regulator. Image credit: saabperformanceparts.com


b. Work-around the stock ECU

These bunch of mods leaves the tuning parameters of the electronic side alone, and just modify other parts of the system that is needed to get the job done. For example, adding more fuel is the pressing need for turbo conversions. Changing the fuel pump and the fuel injectors to higher flow specifications would fulfill the engine’s new fueling requirements on full load. But on idle, you’d flood the engine, as the ECU still thinks it’s injecting X cc’s of fuel when in fact the injectors are squirting 2(X).

Instead, for low boost applications, the mechanical modification is a rising-rate fuel pressure regulator, where the fuel pressure is increased in relation to boost pressure, thus providing more fuel to the engine, without changing injectors. This solution is not perfect, however. There will be a limit to the flow of the stock injectors, even on elevated pressure. You will eventually have to replace the injectors, to the detriment of idling. Fortunately, there has been progress in aftermarket tuning and we don’t have to rely on work-arounds anymore.



Installing a resistor to the coolant temperature sensor. Click the image to the source of this picture, featuring a great installation guide by Dino Savva for this cheat.
Installing a resistor to the coolant temperature sensor. Click the image to the source of this picture, featuring a great installation guide by Dino Savva for this cheat.


Another work-around that is purported to work is installing a resistor in-line with the car’s stock coolant temperature sensor. How this works is that the engine adds more fuel than otherwise during cold starts and cold weather. When you fool the coolant temperature sensor to sense things cooler that actual, the ECU will thus peter out more fuel, adding slightly more power when putting the pedal to the metal. Just don’t use it in stock-class racing, because that would be cheating. *wink*

Note that there are many other work-arounds – too many to list in this guide – and many are still used as part of a proper turbocharged setup. But there will be some cases where the car’s ECU cannot be hacked or replaced. Autospeed has a great article on their exploits on turbo-ing a first-generation Toyota Prius. The stock ECU has to control both a gasoline engine running an Atkinson internal combustion cycle and an electric motor. How does one add a turbo and tune such a thing? Check out this link for how they were able to get this “hybrid” running properly.


Haltech Interceptor piggyback ECU. Image credit: jayracing.com

c. Tweak the stock ECU with a piggyback

In the early days, the average Joe was not able  to tune his stock ECU’s settings. There weren’t as yet open-source solutions to hack through the stock ECU programming. Programmable ECUs used to cost as much as a decent car, and the tuners capable of messing with them were like mysterious warlocks, distant in space, time and size of ego.

Here came the piggyback computer. For Filipino enthusiasts at least, the first tuning godsend was the Apexi S-AFC, the piggyback fuel computer with a fancy blue display. Since the S-AFC can only mess with the fuel timing, Apexi came out with the less-known S-ITC to advance/retard ignition timing. Early EFI super-tuned cars worldwide ran a whole bunch of piggybacks to allow the car to run with some modicum of civility and reliability, but they weren’t too perfect. Integrating fuel control, ignition timing, extra injector control, boost control, and other such functions were something of a miracle solution. For many enthusiasts in the PH, it is the GReddy e-Manage that is the wonder piggybox.


APEXi S-AFC piggyback computer. Image credit: japandyno.com


A piggyback works by interfacing with the engine’s electronic engine management paraphernalia and outputs the tuner’s desired outcome, which may be very different from the stock program of the ECU. It reads the stock setup’s inputs and can give its own outputs towards fueling and ignition to get the car running properly. Depending on how the piggyback is wired and tuned, this setup may combine the strengths of having both a stock ECU and an aftermarket ECU. The stock controller can be set to handle non-boost operating cycles, perfect for daily drivability, emissions, and fuel economy considerations. The piggyback, however, comes on-line only when boost is detected, backing timing and adding fuel as and when needed, to get the car running powerfully and happily.

Going back to the problem tackled earlier, instead of going with a rising-rate fuel pressure regulator, a piggyback can instead run a single or a bank of additional fuel injectors to provide fuel during boost. That raises the allowable boost pressure the engine can run in, to a point where the ignition timing has to be adjusted for it to safely run more boost. With a feature-packed piggybox such as the e-Manage or the Dastek Unichip, even that point can be safely breached. Idling is unaffected as the stock ECU handles that aspect. And piggyboxes are not too expensive to procure and tune.


Dastek Unichip. Image from classified ad entry at olx.co.za


The rub with piggybacks is, well, the stock ECU. ECUs in modern cars are very smart. Regulatory and economic requirements dictate trouble-free, emissions-compliant operation at all environmental conditions. Thus, modern ECUs have a feedback loop, via use of oxygen sensors, that detect abnormal combustion, resulting to poor emissions. When it detects what it thinks is abnormal combustion, it will do what it can to bring it back to normal. I guess it’s like organ transplantation. The body’s immune system attacks the foreign object, even though it be a new kidney giving a second lease of life to the patient. Doctors fight the response with immunosuppressants; piggyback tuners have to do the same on their end. They’ll get your car running well and running hard, but if you see the check-engine light constantly flickering like a misplaced firefly, you might just have to bear the minor irritant.

I would recommend piggybacks such as the e-Manage, Unichip or the Haltech Interceptor (pictured above) to people with low- to mid-effort tuning setups, whether N/A or turbo. Higher-effort setups like Project Elantra require a high standard of tuning. (I would like to think that our Project car is on a high level of modification, but in some eyes, maybe not.) For many common tuner cars, that higher level is very accessible by the ability to retune the stock ECU. For other cars, the only choice is to wire in a programmable ECU.

Next Time

I’ll cover the remaining half  and conclude the guide in Part II. I hope that you guys will stay tuned (geddit?) for that. In the meantime, if you are reading this and have found something wrong with the info herein, I highly urge you to comment via the comments function in this post or via our comment form.

See Part II of this series here!

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