In Australia - and in many markets around the world where they are sold under a variety of names - interceptors have been a resounding success. Despite their being some fundamental limitations in what interceptors can do, their ease of fitment, relative easy tuning and universal application has meant widespread public acceptance. And now there's a new multi-purpose interceptor on the market. Developed by Gold Coast (Australia) performance specialists ChipTorque, the device - named the Xede - promises to open up even more applications for interceptors.
We take an exclusive detailed look at the module, its background and its potential - it's available right now for current-shape WRXs.
ChipTorque and interceptors...
But before we do that, let's take a step backwards. The driving force behind ChipTorque, Lachlan Riddel, has gone on the record previously as saying that the use of interceptors (which - literally - intercept the signals going in and out of the ECU and alter them) is not the best way of modifying engine management. In our most recent interview he said that interceptors "certainly can't do anywhere near the level of modifications that modifying the original factory software can do." In conversation he has been even more scathing, pointing out that interceptors cannot alter the sensitivity of knock sensors, can't alter ignition timing maps such as intake air temperature correction, and can't modify idle speed.
So now that ChipTorque has developed and is marketing just such an interceptor, how does he reconcile this with his earlier comments?
"Fundamentally there is a place in the market for this type of device," he now says. "Whether I chose to think from a purely theoretical point of view it's the correct application to solving a tuning issue or not isn't the question, it's whether people want to use this type of device for simple modifications on specific levels of vehicles.
"If you want to go to a higher level of modification you need either this in conjunction with a chip - if you are not able to tune the chip fully yourself - or you need a complete dedicated engine management system of some description."
So for simple modifications he believes the Xede is appropriate, but for more sophisticated mods either original software re-writing is needed - or a dedicated aftermarket programmable ECU needs to be fitted.
The Xede
Pronounced 'exceed', the product has been the baby of electronics engineer Rhys Drummond, who has developed the Xede from scratch, including both the hardware and software. (Early research into the concept was also carried out by Brenden Ede.) Rhys is proud of his achievement, especially the internal electronics architecture.
"It uses a 16-bit 25MHz processor," he says. "It's quite powerful - made for automotive applications, and temperature rated for that application. We're under-utilizing it a lot because it's such a good processor.
"There's lots of memory on board, which is more than enough for as many upgrades as you want to do. There's also a logic device which does most of the processor-intensive functions, and the microprocessor just supports that. It uses a 10-bit ADC [analog to digital converter] which means that there's 1024 levels."
Those 1024 levels equate to a resolution of just 0.0048 volts when working on a typical 0-5 volt signal. This also gives the interceptor the ability to work with oxygen sensor signals - that is, 0-1 volts. The ability to create a lean cruise function, or - alternatively - run richer in closed loop to overcome the stutter in a cam'd engine is now available.
"When you've only got a zero to one volt signal," says Lachlan of working with oxygen sensors, "you've got to have absolute fine detail in the resolution to either replicate that signal or modify it sufficiently."
Oxygen sensor signals can change very rapidly, so how fast are the analog inputs updated?
"It's in the order or four to five hundred times a second," says Rhys.
And on the frequency side of things (eg when monitoring a speed signal or crank signal)? How fast is the device at working with these very important inputs?
"That's happening as fast as it can, which is at 14.765 Mhz."
"Higher speed means higher ability to make smooth transitions," suggests Lachlan. "The ability to make a change in analog or timing based signals that are sufficiently smooth that the [original car] computer isn't going to get upset - in particular, misfire detection.
"A common problem in other interceptors that I have seen and used is that the misfire detection circuits will be quite upset about small changes in ignition timing signals. They assume that engine has missed, or if it happens repeatedly, they assume that there is a fault with that cylinder or the crank trigger. In either circumstance, they'll go to a default condition and not provide the result that you're looking for."
And it's not just getting the smooth transition right, but also getting the shape of the signal waveforms correct when they are reproduced. Says Rhys: "The way we reproduce the timing signals - from a reluctor type sensor anyway - is to actually reproduce the signal in it entirety, within reasonable limits of voltage, rather than just generating a pulsetrain output that [attempts] to represent that, which is I believe what most other interceptors do."
An interceptor such as this has the potential to be used in a wide range of applications - much more so than the basics of altering fuel and ignition. Automatic transmission control, electronically-assisted power steering - even stability and traction control should be able to be modified. However if it is to be used in more than just engine applications, it will need a multitude of inputs and outputs.
"It provides for three analog signals to be used as inputs," says Rhys. "Two of those which can be modified and sent out as outputs, and the other one can be input only. One of those analog inputs can be sacrificed and made into a frequency input and output. There's also the two timing signal inputs and outputs for a crank and a cam, if they need to be regenerated. There's two auxiliary inputs and outputs, and two PWM [pulse width modulated] drivers. And there's a bi-colour LED output, which just indicates the status of the Xede when it's waiting for the car to be started, when it's running, and if there's a fault or an error or anything like that."
ChipTorque is a company extremely familiar with both factory software and all of the main aftermarket programmable engine management systems. In fact, it would be no exaggeration to say that they are in a unique position to pick and chose from the good and bad that they see.
"We looked at what was possible from a ground-up design," says Lachlan, "and included all of the features that were pertinent from current automotive engine management systems like MoTeC and Autronic - all the things that we have used that were functional and had good ideas in a complete dedicated engine management system - and applied those to the design of an interceptor-based system.
"We wanted the same sort of functionality, in particular the flexibility of changing rpm points and changing map load points - we aren't fixed to a certain set of load points. If you want to have nothing happen for the first sixty percent of an analog input and have all of your resolution dedicated to the next forty percent, that's entirely possible - in fact, desirable in the way our system is set up."
The availability of software for the commonly available interceptors has been an interesting feature of the modification landscape. While aftermarket engine management manufacturers usually make the software for their boxes available free or at nominal costs, some interceptors have been available only with jealously guarded software. Basically, unless you take your car to a dealer to have it tuned, you were stuck. It's not clear whether this will apply to some versions of the Xede.
"The software will be available in various levels, some of which may be available to the general public to adjust their own settings," says Lachlan. "Certainly they will be available to workshop levels who want to do their own settings - who want to password lock their own settings - so that they can have individual set-ups that are their own and can't be read by other tuners."
A key consideration in the approach that is taken to modification is cost. At this stage the Xede is being built in small batches, and so the cost - while competitive - is higher than we'd like to see.
"With the most basic harness, it should be around AUD$840-$850," says Lachlan. "We haven't released the basic harness versions of it at this point in time - we've only released the Subaru-specific versions which are a direct plug-in and contain the Subaru harness section of it. They're AUD$990.
Wow, so many dollars for what probably costs in raw materials AUD$200...
"I'd be happy if you'd like to pay all of our research and development salary and allow me to produce it at the physical cost of the device...." finishes Lachlan triumphantly.
But what about releasing some cut-price, simpler versions - complete with home tweaker software? A boost or water injection controller, for example?
"At this point in time it's not going to happen," says Lachlan, "but it is feasible. The car obviously has some method of engine management on it originally - why not use the function of being able to modify engine management at the same time as to control your water spray and boost control and so on?"
But it's in the current shape Subaru WRX where ChipTorque see the big potential - especially since the WRX factory engine management still remains a black hole.
"At this point in time we don't have the information on the microprocessor that's in the current '01, '02 Subarus so I guess [the Xede WRX kit] is killing two birds with one stone. There was a request from - particularly - America for this style of product where they could modify it themselves and use it in multiple applications. We did it on our own test vehicle here to see whether a stable and suitable result could be achieved for the types of kits which were being done for this application, rather than going into development of the chip. We will probably come back to the chip shortly."
At first look the Xede appears to be a fresh new approach to interceptor-based engine management modification. With its resolution and speed it should work very well in the traditional areas of fuel and ignition, while its ability to work with oxygen sensor signals opens up a whole new field to explore. And with the increasing popularity of variable cam timing and electronic throttle control, we can see this product also being used in far wider fields...
www.chiptorque.com.au
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