While we have run many stories on programmable management, we've never covered the step-by-step process of fitting management to an engine. So that's exactly what we do here. The car's a 4WD Australian-delivered Mazda 323 Turbo (yep, they sold a few) that comes as standard with the B6 1.6 litre intercooled 100kW four.
But first, a bit of history on the car. Mods that had been performed before we got to see it included the fitting of a big exhaust and the installation of a new exhaust cam. The engine had been rebuilt at the time of the cam change, with the engine builder also running the car up on a dyno. This had shown that it had needed a little less ignition timing and a bit more fuel, and so the car went off to have its standard management chip re-mapped. Then it was found that it wouldn't start, let alone run... The owner went back to the engine builder, who suggested that fitting programmable management would get away from the apparent chip problems - and would also allow the appropriate tuning to match the mods. So that's the background.
John Keen of Adelaide's DAT Racing got the job, and he picked a management system of which he is a fan - Autronic. An SMC unit was installed, with the total bill (including the unit, sensors, fitting and mapping) being A$3200
This is how the car arrived - just off the back of a truck. The airflow meter cover was missing, the ignition coil was held onto the wrong bracket with one bolt, the aftermarket air filter had holes in it. Whether it was a result of the previous workshops not taking enough care, or that simple maintenance had been sadly lacking, things didn't look good. And remember, the car wouldn't even run.
The first step that John undertook was to remove enough of the plumbing and top-of-engine bits and pieces to allow easy access. If doing the same, remember that the wiring to the injectors, distributor, coolant and intake air temp sensors, throttle position sensor and ignition coil will all need to be easily accessible. Note also the rag in the throttle body and (out of sight) in the turbo's compressor exit.
Rather than use the new Autronic loom right up to the standard injector plugs, John decided to extract from the under the bonnet a sub-loom fitted as standard. This contains the four injector plugs, coolant temp sensor and idle speed control. Note the large plug at the left-hand end of the pic - if John could wire the Autronic to the ECU side of this plug, the sub-loom would plug straight into the wiring going to the new computer. Nice and neat.
To suss out the wiring in the sub-loom, John checked the colour codes and then got to work with a multimeter. He wanted to ascertain which wires were for the injectors, which were for the sensors, and so on. But he also wanted to see whether the Mazda was wired to have sequential injection - that is, did each injector have its own pair? If not, the sub-loom could be changed so that this was the case.
It turned out that there were enough wires to run each injector individually, so after John had jotted down the colour codes, the original factory sub-loom could be re-installed, ready for the wires on the other side of the standard plug to be cut and then connected to the new Autronic loom.
And that's exactly what was done. With each wire individually covered in heat-shrink (and then later wrapped along with the rest of the loom) a neat and durable wiring harness resulted. The sub-loom can still be unplugged (eg if the engine is being removed) and the wiring around the injectors and other sensors that are still used is of course factory neat.
One new sensor required was for inlet air temp. The Autronic unit will not work with the standard Mazda sensor and so the alloy cross-over pipe from the intercooler to the intake plenum was drilled and tapped to take the new sensor. On a turbo car, this sensor should be located after the intercooler. The standard engine coolant sensor was retained with the new system.
A new throttle position sensor was also needed. The Mazda sensor was removed and then a thick alloy plate cut out and screwed to the original bolt holes. It was then drilled and tapped to take the screws from the new sensor. For neatness, Allen-key bolts were used. The 'D' end of the original throttle shaft matched perfectly with the opening in the new sensor, with the direction of movement also being the same.
A new Bosch ignition module was required to trigger the new single coil. The module demands that it be placed on a heatsink, and John chose to integrate the heat sink with the module mount. He cut out a bracket from thick aluminium angle and then drilled it for the module bolts and a single body-mounting screw.
The module was then mounted from an original tapped bolt hole, there to locate a relay. (The relay was mounted lower on the inner guard.) Heatsink compound was applied between the module and its bracket before it was screwed home.
Next up was the wiring of the module. While John has fitted many Autronic systems in the past, he still checks what he is doing against the supplied wiring diagram. Compared with a factory ECU loom, aftermarket systems are fairly simple - the wiring diagram is included at the end of this article.
Next the Autronic loom leading to the ignition module was sized and cut to length. Always plan the cable runs carefully, leaving enough slack that tension won't be placed on the cable - but not so much cable that there is an obvious surplus.
The Bosch plug that connects to the ignition module uses slip-in pins that are crimped to the wires and then inserted from the back of the plug. Using the correct pins and the correct crimping tool gives the best results. Note that these pins should not be soldered to the wires, as the stiff join then resulting can cause the wire to become fatigued and later break off at this point. Soldering's fine in some situations though - as we'll see.
In installing pretty well any engine management system the trickiest bit is interfacing the ECU with the engine crank or dizzy sensors - usually both position and rpm inputs. The standard B6 engine uses a magnetic reluctor distributor, while the BP18 uses a twin optical chopper disc system. Optical switching (and Hall Effect) are the preferred inputs to programmable ECUs, so John swapped in a BP18 dizzy (right). Mechanically, it fits straight in.
The four wires coming from the new dizzy convey both position and rpm signals. However I stress that this is the area where the most problems occur - even the experienced John had to do some fault-finding when the ECU couldn't hear the signals being transmitted to it. The problem? - a reversed connection and some mode flag discrepancies (in older model Autronic software the mode flags configure the ECU to accept certain inputs, enable boost control, etc).
Where a wire needs to be joined to another in-line (and so there won't be bending forces occurring at the join), a powerful soldering iron will give the best connections.
John chose to pick up the main ECU power connection from the cables coming from the back of the ignition switch, adding an in-line 30 amp fuse for safety.
The Autronic SMC is quite a small unit, able in pretty well all cars to be fitted where the factory ECU sat. The plumbing connection at the top-left is for a manifold pressure hose - in this system, the MAP sensor is on-board.
With the car running on a map hastily punched in to get her started, it was time to remove the tailshaft so that the car could be mapped on a two wheel drive dyno. It all looked like it was going well, but a problem was about to loom....
When the car was running it just didn't sound sweet - even for an engine operating on a hastily constructed map. It fact, it sounded awfully retarded. John checked that the timing being shown on the laptop screen matched that actually being experienced by the engine - fine. He then hooked up a vacuum gauge, which showed that vacuum was much lower than would be expected from an idling engine. Even with a hot exhaust cam, it shouldn't be this low...
It was all distinctly odd. John checked the cam timing - yep, that was fine. He then got serious, and pulled off the engine timing belt covers and outer crankshaft pulley, so that the timing of the cam belt lower pulley could be checked. Hmmm, the lower pulley hadn't been put on properly and was rocking. The keyway had been chewed out, and so the cam timing was all wrong. Back to the engine builders....
Once the cam timing problem had been fixed, the car went back onto the dyno and proper mapping was started. As with many people these days who do a lot of management mapping, John already had a Mazda engine program that proved to be a good starting point. Used in Chris Higgs' awesome Laser turbo ("Try It On!"), all it needed to be correct at lower rpm and in the mid-range was a global adjustment of fuel - in other words, bringing down the fuel values everywhere by an equal amount.
Using his newly-acquired Autronic air/fuel ratio meter to accurately measure real-time mixtures, at higher loads John found that he had to lean-out the mixtures (using the high power BP18 as the base map, remember) - as expected, the Mazda had worse intake airflows in this area.
In fact the limitation to power development in the Mazda was the fuel flow. The injector duty cycle with the standard injectors still in place got very high - here it's 92.6 per cent. Any more power would need more fuel, which would need bigger injectors (and probably a bigger fuel pump, then a new intercooler would be nice...) so John capped the rev limit at 6500 rpm to keep injector duty cycle within reasonable numbers (ie less than 85 per cent).
In this form peak power was 95kW at the wheels. However, the Autronic system gives an infinite room for further modification - with better intercooling and an upgraded fuel supply, adding another 30 per cent or so in the area of power should be only a few more key-strokes away. And then there's the possibility of a bigger turbo....
Contact: DAT Racing + 61 8 2774222
|