The biggest problem associated with programmable management systems - other than cost - has always been the complex installation process. But owners of 1999 - 2000 Subaru WRXs are in luck - you can now buy a programmable Autronic replacement board that plugs into your existing loom and hides in the original ECU case. There's no extra harness, no additional relays and no wire cutting or splicing.
And at AUS$1950 RRP, it's a relative bargain.
The Autronic 'plug-and-play' replacement board is based on the universal-fit SMC programmable management system. This means you get a PC-programmable 16Mhz Intel 16-bit microprocessor, 3D fuel and ignition mapping with up to 32 user-defined rpm and 16 load sites (giving a total of 512 sites), closed-loop mixture control and sequential injector firing. High current injector drivers are also available for 0.9 ohm or twin injector applications.
The ignition side of things offers 0 - 45 degrees (crank angle) adjustment in 0.5 degrees increments, the capacity for up to 30,000 rpm and potential to operate direct-fire coils. There is no knock control function.
Other features of the board include electronic boost control, anti-lag, soft rev limiting, fuel pump safety shut-off, altitude compensation, diagnostics, limp-home error function, idle and fan control, data logging and auxiliary outputs (one pulse-width modulated and two on/off). Note also that a 500 kPa (absolute pressure) in-built MAP sensor is used as the engine load input, negating the need for the factory airflow meter.
In short - apart from that lack of knock sensor input - there are all the functions and flexibility you're ever likely to need.
Installation
We went along to Adelaide's Turbo Tune workshop to watch an Autronic plug-in board being fitted to a 1999 WRX. This particular car had already been equipped with a 3-inch exhaust, Trust Airinx pod filter, A'PEXi front-mount intercooler, Blitz blow-off valve, oil catch can and a boost bleed, which worked the standard turbo up to 15.5 psi (just before the factory ECU fuel-cut).
Interestingly, the owner says his big attraction to the Autronic unit was that it allowed the removal of the factory airflow meter - two meters (costing AUS$620 each!) had broken since the fitment of that Airinx pod filter...
Of course, another reason for the move to Autronic was the extra power it releases. The Autronic ECU raises the factory over-boost fuel-cut level (allowing for further increased boost), gives the flexibility for optimal fuel and ignition tuning and, lastly, eliminates the restriction of the airflow meter.
Note that during its visit to the workshop - and simultaneous with the installation of the Autronic programmable board - the owner also had a slightly larger IHI VF30 turbocharger bolted on. Doing it all at once saves needing another re-map later down the track...
Mounting and wiring the Autronic board takes around 30 minutes.
The passenger side interior floor panel is removed, the factory computer is unscrewed from its mount and the harness connector is removed. The computer case is then opened, and the Autronic board and connector plug fastens in place of the original. There's no wire cutting or splicing involved.
Following this, an intake air temperature sensor is inserted into the intercooler-to-throttle plumbing. This wires into the ECU connector pin that's otherwise used by the factory air temp sensor (whose probe is located in airflow meter, which can now be removed). A small diameter hose is then run from the intake manifold, through the firewall into the Autronic's internal MAP sensor.
In most installations, the standard airflow meter would be removed and replaced by a fabricated filter adapter. In this case, however, one of the previously broken airflow meters simply had its internals ripped out and was fitted - this gave maximum intake flow while maintaining a standard appearance under the bonnet.
With the Autronic board installed, MAP sensor hose fitted, AFM gutted and air temp sensor wired in, we were impressed to watch the engine fire into life on the first attempt - this is most unusual when a computer swap is being performed. Furthermore, it also maintained full operation of all electrical accessories.
Tuning
While the Autronic computer arrives with a base program, further tuning is essential.
On Turbo Tune's four-wheel-drive Dyno Dynamics chassis dyno, it was noted the supplied base program ran the engine a bit lean under load. John Keen - the man behind the installation - commented that most pre-programmed computers come set to run rich as a precaution.
In any case, the 'proper' tune was to follow...
The Autronic plug-in board comes standard with a so-called auto-tune program. With the necessary software loaded onto an IBM-compatible laptop, the auto-tune facility enables hands-free tuning on-the-fly. The only thing the tuner has to do is enter their desired air-fuel ratio at each load and rpm point and run the engine through each of those sites. Then, using a wide-band AF meter in the tailpipe, the program automatically sets the injection quantity to deliver the desired mixture.
In this instance, John chose to run the engine at around 15:1 under light load, 14.7:1 under slight load, 13.5:1 while coming up on boost, 12.0 on max boost and 11.5:1 at full power. Some adjustment was also made to acceleration enrichment and temperature compensation on start-up.
The board's ignition timing must be manually entered at each load and rpm site. John increased the amount of advance off-boost and kept on-boost timing around standard. He says there shouldn't be any problem running regular unleaded in an emergency - so long as the car isn't hammered. Remember, though, there's no knock sensor function to help you out...
Also, because John noted the newly fitted VF30 turbo wasn't performing brilliantly toward the redline, he brought the 7500 rpm limit (as arrived in the base tune) down to just 6500 rpm - as he says, there's no point revving it extra-hard if it's not making any more power.
Finally, with the Autronic computer taking over control of the factory boost control solenoid, there's the flexibility to program a custom boost curve. This allows you to specify - say - a reduction of boost pressure as the injectors approach their limit at higher revs. This particular car, however, was set to hit maximum boost - 17.5 psi - as quickly as possible and then hold it.
Overall tuning - which was performed both with the engine cold and fully warmed up - took a total of around 3 hours.
Results
Here's the dyno result when the car ran the standard intercooler, turbo and management, but the aforementioned 3-inch exhaust, 15.5 psi boost, catch can, blow-off valve and air filter.
And here's the 'after' result, with the Autronic management, slightly higher boost and the new turbo.
As you can see, the latest configuration is fractionally down at very low revs. In the lower midrange, however, the new set-up explodes to deliver 40-45 percent more grunt. Interestingly, once past mid-rpm, torque then starts to nose over and there's only 10kW difference across the entire top half of the rev range - there's between around 160kW and a maximum of 170kW. Still, 170kW ATW is a gain of 47 percent - remember, though, that's having changed the engine management, turbo, boost pressure and intercooling. It's impossible to tell how much of that 47 percent power increase came solely from the mapped Autronic board.
Summary
The Autronic plug-in replacement board is by far the easiest - and cheapest - way to get a full-function programmable management system into your 99 - 00 WRX. There's no stuffing about with ignition pick-ups, igniters and all of the other things that typically cause headaches when installing a programmable computer.
It gives the ability to tune for optimum power, you can customise various settings (such as rpm limit), there's flexibility for further tuning later on (like when you bolt on that massive T60 turbo!) and - of course - it allows a freer-flowing air intake. Add to that the functions we haven't yet explored - such as data logging and anti-lag - and you're talking immense potential. Finally, the system is very unobtrusive - the chance of being nabbed for aftermarket management is minimal.
The owner of this particular car came away very happy with the result.
He tells us he enjoys stronger performance in the mid-range/top-end (largely thanks to the larger turbo), factory-style throttle response and a much more stable boost control system. The only downside, he says, is slightly increased lag compared to the standard turbo - 10 psi boost now arrives at 3200 rpm and maximum boost (17.5 psi) arrives at 3500 rpm.
Still, that's not too bad for a big turbo'd Rex...
In terms of dollars, the VF30 turbocharger cost AUS$1450 (sourced in New Zealand), its fitment cost AUS$300 and - finally - the Autronic board cost AUS$1950 (through Allan Engineering) and it was only AUS$500 to install and tune.
A top programmable management system bought, installed and dyno tuned for less than AUS$2500? Amazing.
At last - here's a no-hassle, cost-effective engine management swap; it's great if you happen to own to own a 99 - 00 WRX!
Footnote: Autronic also offers a 'plug-and-play' board for Mitsubishi Lancer Evos (4 through to 7), and a board to suit the 01 - 02 WRX should arrive later this year.
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Important Note!
After contacting the originator of the Autronic plug-in ? Richard Aubert ? we?re advised that the abovementioned price is not the RRP (although that?s what the buyer paid for it? go figure!). The official price for the replacement board is $2300 and the auto-tune software costs a further $200 (prices do not include GST). All inclusive, the system amounts to $2750.
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Contacts:
Turbo Tune
+61 8 8297 1030
Allan Engineering (South Australian Autronic Agent)
+61 8 8527 2266
More Autronic info at http://www.turbofast.com.au/autronic/autronic.html
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