What do we talk about when we use the term re-mapping? We refer to the re-orgainising of the so called mapping tables, which as a matter of fact are only a small part of the ECU's program. Of course, it can extend to further parts of the ECU, but at that point it migh be much better to go for a standaq alone ECU. Whether using a piggy back/tuning box, generic re-map, custom re-map, live re-map or stand alone ECU, they all share the same idea: Altering the fueling and timings as well as boost in froce induced systems. But the end result might be very different using each of the ideas/systems. Piggy back: Some people try to sell resistors as a piggy back. They usually are to bebrought in line with the ambient air temperature sensor. The theory behind this is that the ECU is made believe that the air is cooler than it actually is. This would inject x amount more fuel and the result is that the richer mixture will give more power. So far the theory. But the practical side looks different. The ECU has got more sensors and the one picking up on it is the lambda sensor, which will correct the fueling to a certain extent. The resistor will have no effect on perfromance in a positive way. It will rather loose performance and/or will increase fuel consumption. To rate this idea anyone being generous would give 0/10. Not so generous people would give it less. The real piggy back ECU's or tuning boxes should be quite a bit more advanced. On normally aspirated engines they are of very limited use. In Europe they are only used if other than going stand alone no other alternative is available. The gains usually do no warrant the expenditure. Problem is the they are not capable to adjust the ignition timing. This might not affect the engine to a significant degree, but does not aid performance gains to the degree a proper re-map does. Where it weighs in heavier is when it comes to further modifications where ignition timing is very important to change. My rating on the normally aspirated applications is at best 2/10. In force induced petrol engines I personally would not consider any piggy back (includin Pete's). If further modifications made to the engine I would strongly advise not to use it at all. My rating on the force induced petrol engines is 0/10 On the turbo Diesel applications the tuning box is more acceptable because the crucial ignition timing is not existent. However the tuning box can not replace a proper re-map. Unfortunately not all ECU's can be re-mapped. This is where the piggy back is a winner. The only real other advantage is the convenience factor. It can be easily installed and removed. But it isn't working on all ECUs, because some late ECUs are so smart that they effectively will override the tuning box. Also quite a few ECUs now can 'see' an alteration and log on a fault code. My rating on the Turbo Diesels where it is the only alternative solution is 4/10. For all other applications it is much less! Stand alone ECUs: Stand alone ECUs are the most flexible solution in performance tuning. But this comes at a price. Additionally there are 2 problems to it. One of them affects the daily user the other effects the daily user as much as the professional racer. The first problem mentioned is due to the fact that a lot of driving is done with an engine warming up. Warming up is for the software designers a real head ache. A cold engine needs overfueling (which is why carburettor engines have a choke). But the dosage is rather tricky. To get the balance right it takes a lot of testing (costing manufacturers at present over 10 million USD per ECU in man hours alone). This we can't get right with reasonable cost. The other problam that the user of a standalone is being confrontet is the map in general. Every parameter needs setting, which sounds much more complicated than it is. It is easy to decide the different inputs (sensors) to be used and the same goes for the outputs. Where it gets involved is the actual mapping. None of the ignition advance tables are set. And none of the fuel tables either. And if it is turbo applications it will get even worse. To get thing to work properly a rolling road with an Eddie current unit needs being used assisted by a lot of road testing, where you need a second person on the lap top. And this gets expensive. But the reults are rewarding. My rating for road use is 9/10 because of the warm running issue. For all other applications it has to be 10/10. Generic re-maps: A generic map is usually coming from a test car that the supplier of the software has developed. This is fine for the car that it was done at, but doesn't mean it is all that good. First of all these maps are done on new cars that aren't even run in properly. Then a couple of things are underestimated. Every engine is slightly different. When we had on some rolling road days a number of cars of the same model with the same engine. We had AFR graphs differing as much as torque outputs. This was not only because of tolerance issues on the engine but also because of the fuel used and some other reasons. A generic re-map will be useless when it comes to modifications. When a proper induction kit is installed it can combined with a generic actually lose perfromance against stock. My rating for the generic re-map is 4/10. Custom re-map: The custom re-map is a hevily misused term. Strictly speaking any modification of a re-map could be called a custom re-map. To do it properly a rolling road is needed. Before any re-mapping is being done a couple of runs on the rr are done with an AFR graph (unless it is Diessel) and the troque curve and boost in force induced engines. From there the mapping tables are looked at. If it can be live mapped then it will be done constantly on the rollers while running the car, but this is not possible with most of the modern ECUs (more in live mapping about that). A professional mapper is more than an oldschool mechanic and therfore is able to read out of the graphs what the map has got to be to make the best gains. But the improvements done will not be the optimal results. This can only be done by quite a number of runs and map alterations. However a good mapper gets very good results that are very close to the optimal results within an acceptable finacial and time frame. My rating on a custom re-map when done by a professional is 8/10 Live re-map: We are talking a bout a live map, when the ECU can be accesses with an emulator that makes the ECU believe that the lap top attached to the emulator is the actual memeory. This way the mapper can alter the values in real time on the rolling road. By using the Eddie current unit rpm and load can be held at any point wanted. This way every mapping point can be addressed and optimised. This is as much a custom re-map as what is classified in general a custom re-map, but has got the advantage that the live re-map can be done much faster in real time than any other map. Any custom map can be made as good as a live map when enuogh time and money is at hand. The live mapping is not possible with all ECUs. It is only possible when the ECU can be 'extended' to a memory that is outside the ECU and be live programmed. It can not be done through the OBD socket. Difference between chipping and re-mapping: The difference between chipping and re-mapping is the physical action. Chipping is referred to as removing the chip (memory) of the ECU by ar e-mapped chip. Technically it is the same programming job. Re-mapping is usually referred to as up loading the program throught the OBD socket, pinning the ECU or using a BDM apaptor. Some ECUs can be programmed/re-mapped by using either method, most of the old ECUs can only be chipped and many of the modern ECUs can only be re-mapped. But whatever needs to be applied it all is re-mapping.