Remapping as far as it is concerned for guys like me who worked with OEMs. its changing specific .C files ( we add certain _msg if new sensors are added or just change the values of _C parameters ) and create a new HEX file and then loading the recommended DCM file which will ahve new setting for calibration parameters which are meant to have setting that improve the performance of the engine based on Customer request.
then run this new HEX in a Closed loop VIVA lab car and then monitor A-Z for 1000 Start and driving cycles together with temperature profile testing after keeping the ECU in temperature chamber.
once this is done , the eCU is sent for series production with this NEW HEX file inside it.
this is how OEMs Remap.
tuner remapping is like an easy way to do the change to all parameters by studying the END product of the ECM software life cycle. based on the 1000s of .C individual files, a HEX file is generated .
HEX file represents the whole thing. it has got HEX values written at address lines which start from 0000H to FFFFH ( this is a typical example in reality its much more complex) so from address 0000H to 0056H might be for example injection limiter or any one parameter the map-location that is the term for finding the meaning of the data at given address lines. so a tuner reads the HEX file which came inside the ECU of the car, changes it ( usually .HEX , .bin, ORI file format etc ate there) and then writes the same into the ECU inside the CAR. as an Engineer all i can say is when a tuner knows the exact tolerance ranges of all the components that would get modified behavior due to the remap, then only he should remap. trial and error remapping is asking for trouble IMHO.
if the values are altered and then a corresponding checksum is calculated and both the new file is written to ECU and the checksum in the ECU is updated, once the start up diagnosis happens the eCU checks for concurrency between memory in flash and memory in eeprom! if a mismatch is there. then start again!! Good luck!
so what is mentioned above is how tuners do it. they use software like WinOLS, then Tuenr PRO, Tactrix ECU flasher KWP2000 flashers etc to read the HEX files ( any HEX editor will work! ) then write this back into the ECU and take care about the Checksum. thats about it.
so then remapping what types??
well this also depends on the approach.
before i explain about remapping one word of advice . Have a SPARE ECU. this is one step that can always bail you out should something go wrong. but then again anything electronic in the car can go for a toss if the value fed is wrong to a particular actuator!!
in car remapping is done through the use of KWP2000 ( a communication protocol used for automobile ECU) connected to the OBD2 port.
CAN Programming can also be done. but a simple problem Vector tools are obscenely expensive a simple CAN CARD can cost 3-5 lakh rupees.
this is a risky one as one hiccup in car power level or mistaken flip of switch of key from batter y to ignition position etc, or even a problem in the laptop used like a crash for example can land you with a locked eCU or worse a bust one!!.
then there is chiptuning, here the EEPROM from the PCB of the ECU is taken out and reprogrammed or atleast the eCU is taken out of the vehicle and using a LAB power supply hooked up and then the reprogramming is done.!!
the thing with Remapping is that.
you play GOD more or less. you get to control almost everything . things you should control and things you should not control also!! this makes remapping all the more risky!! so always have that bloddy spare ECU with you!!!
then the most advanced one is the live remapping, this is done with the use of ECU emulators which will have a running car hooked onto a dyno and remapping can be done in real time when the car is running in dyno to achieve optimum results.
but now a days the CRS systems are so complex the Emulator will have to emulate a Body control MOdule. which is like asking for trouble. this method is done ,more or less on gasoline vehicles!! . since the system is more simple there.
ok then stage1, stag2..stage x..??
stage 1 remapping doesnt warrant any change in hardware more or less a stcock car can be used. stage 2 onwards hardware upgrades are required.
a simple problem with HEX files is that eveyrhting is in HEX format and based on the starting adress and ending address a HEX table is formed which controls a particular parameter, torque limiter, gearbox torque limiter etc.
if the tuner sets any one parameter at a value which is dangerous to the component it is intended for , then trouble!!
simple example is in laura and BMW 5 series remapping with DSG gearbox , the DSG BOX MAP is best left untouched, since it changes or shifts based on the torque output from the engine. so what happens is though after a remap more power is produced , the DSG box will shift up much earlier!! so what a tuner does is he plays with the DSG map making it shift up at a higher torque rating! this will simply lead to DSG box going Bust earlier!! ( simply put a lot of R&D had gone into those settings so that the DSG Box lasts!!)
here a hell lot of freedom is available, but its more or less hell risky also!! turbo tuning with VGT turbos is a pain altogether unless you are well versed in the particular algorithm that the VGT is controlled through, the MAP should not be touched!!
the problem with the re-mapping is that the base map which the tuner in europe work on is based on the european maps. the indian maps are always different. the main changes coming in the turbo tuning, EGR tuning, and also when injector and rail pressure mappings are altered, the first thing to be made sure is that the injectors and rail can take that kind of abuse, the OEMs test the inejctors with specific injector duty cycles which are never agressive in nature since injectors and rail are NOT REGULAR changed items while running. its supposed to last as long as the engine.
now suppose the normal duty cycle is 5
60% max and 20% min for a set rail pressure. of min 800BAR and max 1500bar!. 70% duty cycle at 1500bar is already bad on the injector . but when the rail pressure changes to 1600bar and duty cycle is changed to 70%?
the stress on the injectors are increased exponentially, it can give irratic behaviour.
in case of tuning boxes, there is no mixed trouble like this. the tuning boxes cannot alter what is inside the ECM hence tuning BOX is a reasonably logical safe bet for a stock car. but when bigger inejctors are swapped on, turbo upgrade etc. remapping is the way to go. but a small thing to be kept in mind is .
FIND out how much the internals of an engine take and then only go ahead with remapping!! . remapping is boundless it can be used to create hell lot of power gain ( if the internal cant handle it, the engine will be shortlived!!)
mainly injectors, fuel metering system, turbo boost pressure, rail , High pressure pump, Glow control and EGR control is remapped while a remapping is done.
IMHO remapping should be done only when one wishes to go for real deal as in hardware upgrade of injectors, turbo , pump etc. ( performance events like drags, track use, rally use etc.)
for normal street use tunin boxes are more safer bet.
so as can be clearly seen Remapping is more better for better power gain!. but unless done properly its hell dangerous. has the potential to DESTROY!!!
tuning on the other hand has got the ECM left untouched and also has an inbuilt safety bypass whould the box screw up, it gets bypassed and ECU does all the work. in remapping, nothing doing! the remapper should ensure all the safety measures are left untouched or changed properly.
steps to be followed for Box is.
if IM type available. Go for it. Deal closed. use better filter if needed.
RPM type. use with caution never exceed the Box manufacturer limits. as in put jumpers to increase rail pressure even more!! not a good idea. latest gen are IM types so more or less. thats said and done.
be ready with Sapre ECU atleast and always get a GOOD MAP file. do not go for Clone tools!!! ( buy original software!! ) its hell expensive but well worth the investment. then comes the blue printing. get the service manual of the vehilce and check how much abuse all components can take!!.
this step is really necessary if you wish to go the full deal.
get the Software Docu for the ECU. how you get it is left to you!!! . it will only help!.
and make sure that remapping is done keeping in knowledge the upper limits of each of the Maps. and where ever possible. try to get the latest software for the Engine. its a known fact that OEMS often update MAPS on the vehicles while service happens. so keep all in mind.
advantages and disadvanatages are there on both sides. its the Use and application and GREED!! that tilts the scale to either side!!. my report is more or less over. feel free to ask Qs will answer to the best of my knowledge. i have kept the real deal with OEM tunign and Remapping due to obvious reasons!! but what tuners do is more or less what i have explained.
thanks to everyone for their patience and acceptance of this report