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The connection to the modified ECU is made by fitting this BNC socket. The “BAAM VP Auto” label refers to the car (a VP Commodore with automatic transmission) and the unique broadcast code of this MemCal (BAAM). By JULIAN EDGAR Reprogramming the Holden ECU Real-time reprogramming of Holden’s ECU (electronic control unit) is now possible thanks to a very clever software package. It takes the guesswork out of optimising performance if engine modifications are made. No major car company provides software that allows its engine management system to be reprogrammed. This means that anyone who is capable of reprogramming the main chip in the ECU has previously been involved in some clever detective work, to find out how it works! Some aftermarket companies make chip changes on an experi­ mental basis, altering a byte and then observing how the engine responds to that change. In that way, they gradually build up a picture as to which parts of the program control which aspects of the engine behaviour. A radically different approach has been adopted by Ken Young, the programmer behind the Kalmaker (former­ly DynoCal) package. Ken has identified the function of each byte within the dozen or so programs used by Holden in its various ECUs and has written a software editing package to suit. Basically, the Kalmaker software runs on a portable PC and allows real-time reprogramming of the Holden ECUs. As indicated in the July 1997 issue, the Holden ECU is based on a MemCal. This is a plug-in module that contains an EPROM (for program and engine data) plus DIP resistor packs to provide engine fuel backup values. The rest of the electronics within the ECU module includes the injector drivers plus various counters, timers and so on, as required in any engine management system. The EPROM in the MemCal is not amenable to byte-by-byte reprogramming. To get around this problem and to allow data changes “on the fly”, the MemCal is replaced with a new PC board dubbed a “Real Time Board” October 1997  37 GMH 16K ECM Programs H35 Base program used on 1.8l TBI Camira H54A H54B 1.6l TBI + 1.8l PFI Pulsar/Astra 2.0l PFI Camira H5D Late 1.6l TBI + 1.8l MPI Pulsar/Astra? Late 2.0l PFI Camira, also VL Walkinshaw & VN V6 & V8 FVA FVB FVC FVD Series of programs for Formula Brabham V6 HA5 Used on later VN V6 only HB1 Minor change used on VN V6 & Group A V8 HDB Group A V8 & HSV HFB Used on all late VP V6 & V8 H03 V6 LPG GMH 32K ECM Programs H12A H12B VR 3.8l V6 & 5.0l Manual Transmission H3C VR 5.7l V8 Manual Transmission H5B VS 5.7l V8 Manual Transmission H5A VS 5.0l V8 Manual Transmission GMH 64K PCM Programs H11A H11B H11C VR 3.8l V6 & 5.0l V8 with 4L60E H2A VR 3.8l V6 LPG H3D VR 5.7l V8 with 4L60E H59 VS 5.7l V8 with 4L60E H84 VS 5.7l V8 with 4L60E 96 transmission update H58 VS 5.0l V8 with 4L60E H83 VS 5.0l V8 with 4L60E 96 transmission update Fig.1: a number of different ECU programs have been used by Holden over the years. Each of these needs a script containing data ad­dresses and other information purpose-written for it. 38  Silicon Chip (RTB). This contains a static RAM and a series of resistors. The resistors calibrate the engine’s fuel backup values and also tell the ECU how many cylinders the engine has (the latter is done in both the hardware and software). The static RAM contains both the program and the engine management maps and it is the latter that are changed during reprogramming. Connecting up A coaxial cable is used to connect the PC to the ECU. One conductor is a ground while the other connects to the data port already present on the ECU. This port is normally used to read sensor data for fault diagnosis and several commercially-available tools are available to do this. One aspect of the Holden system that makes it amenable to program manipulation is that the data port is bidirectional. It is used by diagnostic tools to temporarily disable the input of a sensor, allowing easy fault diagnosis. If, for example, a coolant temperature sensor is suspected of having an open circuit in its wiring loom, it can be software-disabled and the resulting engine change studied. This bidirectional port has its origins in the US On-Board Diagnostics (OBD) legislation, which requires that vehicle emissions be kept within certain parameters for long periods. The Kalmaker software modifies this facility, using it to write the transmitted data to the static RAM rather than just using it to disable a particular input sensor. The program addresses are contained within the individual Kalmaker scripts. The Kalmaker program itself is just a general purpose editor; it’s the scripts that contain all the intel­ ligence and a script has been written for each of the different Holden MemCal programs. Fig.1 shows the different MemCals that have been produced over the years. Note that there are often update MemCals within the one model. However, these only change the program data (rather than programming technique) so they don’t need a new script. Using the bidirectional port to write directly to the static RAM gives seamless changes in real time. This is important as sudden mixture or timing changes can be dangerous if the engine is being run under load on a dyno during the reprogram­ming. The MemCal is replaced with a Real Time Board which contains a static RAM chip (the empty socket) and resistors that configure the backup fuel maps. Another approach used in some systems is to use an EPROM emulator in conjunction with a standard EPROM. Each time a data change is made by the emulator, the ECU toggles to the standard EPROM, covering up the data gap, so to speak. This can cause hiccups as the engine is momentarily run by a program that is no longer ideal for the operating conditions. It’s for this reason that the Kalmaker program avoids this approach. The serial data cable connects the PC’s parallel port to the ECU via an interface board. The interface is needed because the ECU high speed serial data link does not conform to RS232 specifications and its baud rate is 8192, not the standard 9600. The interface board allows bidirectional communications via the PC’s parallel port status lines. The PC can then poll the paral­lel port for incoming data in a similar fashion to Laplink’s PC-to-PC communications software. Reprogramming a Holden A development ECU is used during the real-time reprogramming. Once the program is correct, it is burnt into a normal MemCal’s EPROM which is then re-inserted into the standard ECU. If the engine has been modified or its operating parameters changed (eg, if premium unleaded fuel is always used), changes can normally be made October 1997  39 SILICON CHIP This advertisment is out of date and has been removed to prevent confusion. SUNSHINE DEVICE PROGRAMMERS Power 100 Universal Programmer 48-pin Textool Socket para I/F ............$1371 Hep 101 Value for Money 8MB E(E)PROM - 1 slave socket ...................$283 Hep 808 High Speed 8MB E(E)PROM programmer 1 master 8 slave sockets .. $790 Jet 08 Production Series E(E)PROM Programmer Stand alone or PC (para) .$1590 PEP01 Portable 8MB E(E)PROM series Programmer, Parallel Port ....................$295 EML2M EPROM Emulator ....................$480 Picker 20 Stand Alone IC Dram CMOS Portable Tester ......................................$199 RU20IT 16 Piece UV EPROM Eraser with timer .............................................$187 Plus converters, adapters & eproms. Contact us for other spe­cialised development tools or data acquisition, industrial elec­tronics, computer and electronic parts and service. Available from: D.G.E. Systems; Nucleus Computer; Stewart Electronics; TECS; X-ON. SUNSHINE ELECTRONICS 9b Morton Ave, Carnegie, Vic, 3163 TEL: (03) 9569 1388 FAX: (03) 9569 1540 Email: nucleus<at>ozemail.com.au 40  Silicon Chip Effective engine management reprogramming must be done in real-time on an engine or chassis dynamometer, as shown here. to the engine management program to improve performance. However, for this to be done efficiently, real-time reprogramming while the vehicle is tested on a dynamometer is a necessity. While it would be possible to remove the MemCal, reprogram it on the bench and then plug it back into the car, this approach is very time consuming because the changes are unlikely to give the optimum performance “first go”. Instead, the complete ECU is removed and temporarily replaced with the development ECU con­taining the serial cable plug and Real Time Board. Changes can then be made in real time while the car is under load. Typically, the air/fuel ratio is sensed by a high-speed heated oxygen sensor placed in the exhaust and the engine power checked on the dynamometer at full-load for air/fuel ratios ranging from 13:1 to as rich as 12:1. Both the Commodore V6 and V8 engines develop maximum power at an air/fuel ratio of about 12.5:1. Ignition timing changes are normally made by holding the car at a certain MAP setting (ie, at a constant load) and RPM and then advancing the timing until the rate of the measured power increase slows or stops, or detonation intrudes. The timing is then generally retarded a few degrees from this point. Note that in some cars, no power gain at all can be made by remapping in this manner. Once the new program has been devised, the original program can be erased by removing the protective sticker and exposing the MemCal to UV light. The new program can then be burnt into the EPROM of the MemCal and the MemCal re-inserted in the standard ECU. Contacts (1) KAL Software (Brad Host) – phone 0412 266 758. (2) Awesome Automotive – phone SC (08) 8277 3927.