It's very easy to spend a lot on engine management modifications. A chip, a programmable ECU, a new interceptor unit - the dollars can easily blow out into the thousands. In fact, most people assume that a minimum of $4-500 is the starting point, with $5-7,000 not an uncommon spend. But often that money is wasted.
So far in this series we've looked at how an exhaust will (typically) get you about 10 per cent more power, and how modifying the intake is often good for about 5 per cent gain. Taking a budget approach, that means that for under $1000 you should be about 10-15 per cent ahead. But what do you do next?
That depends very much on what it is that you are trying to achieve.
If the air/fuel ratios are correct and the engine does not detonate, it is a very worthwhile option to make no changes at all to the management system. This has a huge advantage - it costs nothing. This might seem pretty obvious, but many people shell out large dollars to buy a chip, or even replace the management system, when there's nothing wrong with the standard system!
Many people see a chip as a viagra equivalent (in fact, one company advertises their chips using that analogy!). But independent tests have shown that, in terms of peak power, a chip does almost nothing on a naturally aspirated car. Certainly, in my experience it usually does less for power than $10 of stormwater pipe fitted to the airbox. A chip may be more sexy, but it often has less performance. With the fitting of a chip there can certainly be subtle changes to driveability (eg through increased low-load ignition advance), but you're paying an awful lot in relative terms for this change. If you're on a budget, it's simply unjustifiable.
Deciding whether or not the engine is running lean can be done with the assistance of a cheap LED Mixture Meter (see "Cheaply Monitoring Air/Fuel Ratios") or by a logged dyno run with full gas analysis (the latter is better!). Detonation is best detected with a cheap electronic system like the one covered at "DIY Detonation Detection - Part 2".
Modify the Standard System
If the engine is running lean (for example, you've improved the power to the extent that the standard ECU no longer copes) there are plenty of low-cost ways of overcoming this problem. You can increase fuel pressure with a rising rate or adjustable fuel pressure regulator (see "Boosting Injector Flow" for the change in injector flows that result); you can adjust a vane airflow meter to enrich the mixtures; you can fit larger injectors and then modify the load signal coming from the MAP sensor of airflow meter to compensate (see "DIY Bigger Squirts" for one effective technique). You can enrich the fuel supply by making the ECU believe that the engine is cold, and you can retard ignition timing by making the engine believe that the intake air is hot. These mechanisms can be switched in and out with throttle or manifold pressure switches.
If you work carefully and test each change, taking these sorts of measures will result in very good results for almost no money at all. When dealing with a budget car (say $3-6000) this is the approach that I would always take. However, few workshops know much about these techniques, so you'll be mostly on your own.
Real Time Re-Mapping
Factory engine management systems of the last ten years (15 in some cases) are much superior to most aftermarket systems. This point is often glossed over, but companies like Bosch and Delco have standard ECUs which have far better functionality than cheapy aftermarket boxes. This means that if the standard management system can be re-mapped to match the modifications, the results will be superior to all but the most expensive of aftermarket ECUs.
However, if the re-mapping doesn't occur in real time with the car on a dyno and the operator tuning the ECU, it's all hit and miss. And very, very few companies can re-tune a variety of cars in real time using good software. In fact, I have seen only one Australian company able to do this with any degree of skill - Queensland's ChipTorque. Many other companies use the 'we'll-see-what-happens' approach (eg "let's increase this number here - that'll change the timing upwards by some amount"), and/or they have little idea what they are doing. Certainly the way in which some of these cars drive after re-mapping makes me strongly believe the latter.
The exception to all this is the quite brilliant Kalmaker software for Holdens, developed by genius Ken Young. Some confusion exists about this software - confusion not helped by competitors suggesting that there's nothing special about it. The software allows the plain English viewing of every single map inside each of the Delco ECUs. The relationship between all of the variables is clear, and there is absolutely no blind man's bluff required when making changes. AFAIK, this software is unique in the world. I have watched Kalmaker being used for many, many hours of dyno time, and am happy to report that it is as clear and simple as a programmable system like Haltech. It's just that there are an awful lot of maps inside a Delco....
At least one workshop in each Australian state has the full package, and if you want to have a go yourself, the software can be bought directly from Injection Connection. If I had a Holden I would not use anything else at all in the way of management systems. Nothing! And in fact when I did own a budget modified Holden, that's just what I did."
The marketing of interceptors has recently risen to new heights (eg with the Unichip). These devices are fancy versions of the simple changes made to the input and output signals of the factory ECU, an approach discussed above. However, they are usually much more sophisticated in that they can be programmed by laptop, and are often two-dimensional (ie they can respond to engine load as well as revs). However, because they work by confusing the standard ECU, there are some things they cannot do. For example, they can't change the speed with which a knock sensor pulls off timing (or the amount of timing it pulls off); they can't change the air/fuel ratios within the closed loop range (eg at idle and in cruise conditions); they can't easily alter the rev limit, and so on.
However, they are very good at making slight changes to full throttle mixtures, allowing the swapping of an airflow meter, or the use of larger injectors. In some applications they have advantages over full programmable management, because much of the sophisticated functionality of the standard ECU is retained. But beware of interceptors that are marketed as full programmable management systems - for both good and bad, they are not.
Full Programmable Management
Cheap programmable systems (say, less than $1500) are mostly crap. People try to dress that up in all different ways, but for a budget car it is far better to tweak the factory management system than to throw it away and buy a vastly inferior system - even if the latter can be tuned. From a cost and functionality perspective, a modest power-up (and that's as much as 35 per cent in a turbo car) is better served by a modified factory system than a cheap and nasty aftermarket system. If you're prepared to take some risks, you can go even higher in power - I've seen turbo cars with double the standard power still running the factory ECU, complete with budget tweaks. In the context of the amounts of money we're talking about, that's a very major saving.
Compared with a cheap programmable ECU (even if it's well programmed!), the factory ECU will usually have better starting and driveability, feature closed loop running which is good for economy and emissions, have accurate acceleration enrichment and deceleration enleanment, have limp home modes and fault codes, and won't have problems interfacing with other car systems like factory security and trip computers. But, just as you can blow up the engine with poor tuning of the aftermarket system, so you can also blow up the engine with poor modification of a factory system. Certainly, it's far easier to make the factory system work with a heavily modified turbo car than a heavily modified naturally aspirated engine.
Five years ago I used to write stories encouraging people to fit programmable management - now at least with budget modified cars, the fashion has swung too far the other way! Everyone seems to fit programmable management, even on the cars where there's no real reason to do so. On a car with modestly improved power, unless you can justify $2000-$3000 (fitted and tuned) for a new management system, stick with the factory ECU. In Australia, the three quality aftermarket programmable systems are Autronic, Haltech and MoTeC.
You want good engine management performance at low cost?
Intelligent Performance, Part 1 - Starting Points
Intelligent Performance, Part 2 - Exhausts
Intelligent Performance, Part 3 - Intakes
Intelligent Performance, Part 5 - Turbo Cars
Intelligent Performance, Part 6 - Engine Swaps
Intelligent Spending, Part 7 - One Man's Approach
- Stay with the factory management system as long as possible.
- In a very budget car, tweak the inputs and outputs of the factory ECU.
- If it is possible, get the factory ECU re-mapped in real time on the dyno. If you have a Holden, make sure that Kalmaker software is used.
- Where this is not possible, use a 2-D interceptor to tweak inputs and outputs.
- Fit only expensive, good quality programmable management systems.