I, like many others, feel that most "tuning boxes" are a real bodge, there are lots of cheap plug in modules on ebay that do little other than change the air sensor readings making the car think the air is colder than it really is and all they contain is a small resistor and a switch or two.
It used to be piggy back ECU's that were all the rage and now these "tuning boxes" are gaining popularity.
There are a few boxes that when connected to the car upload a new map to the car - these deserve to be called tuning boxes as this is exactly what they do, and they do a reasonably good job although this is still off the shelf and a half hearted effort at tuning.
I have heard great things about proper remaps and these really do seem to be the way to go. You get more power and if it is a custom remap it takes into account the condition of your car and any other mods you have had done. Make sure the remap is custom, ie they download your cars map, modify it and then upload it again. Ideally the car should be setup on a rolling road.
I've not looked at the links you've supplied and am not familiar with the companies recommended but as with any mod I urge caution. Get a recommendation from someone who has experienced the mod on the same model of car as you.
Also claims made by manufacturers are often wildly optimistic so don't compare peak power gains - the whole map needs to be taken into account.
You get what you pay for.
Generally yes, you do get what you pay for. But it's still possible to be overcharged.
The cheapest boxes are simply devices which contain a couple of resistors in a voltage divider pair configuration which do, as you say, simply mis-represent some real time data so that the ECU over-fuels the engine.
Others, however, can work very well indeed. In some cases it's the only option if the remapping community hasn't yet 'cracked' the code to a model or manufacturer specific ECU.
Notice I say 'yet'. Time is of the essence.
Even the best of tuning boxes, or the more elaborately titled 'piggyback' ECUs will not be able to determine the car's own ECU's intentions at any particular time. They can all 'stretch' the fuel injector dwell (open) time. Some can allow greater rail pressure lower down in the rev range. Some will also allow for higher boost pressure.
But I still see tuning boxes as crude when pitched against a well designed ECU remap.
Rather than 'fooling' the engine into delivering extra fuel, surely it's better to instruct it explicitly to do so and make sure that the airflow is adequate to take advantage of this.
A good remap will offer silky smooth torque and power delivery with most or all of the flat spots and high spots eradicated. A tuning box only makes a rough torque curve rougher still, even if the the overall power delivery as measured is broadly similar.
There are other issues to consider as well. Euro IV and Euro V diesel engines will have some highly unusual operating situations when the soot filters (DPFs) are regenerating. No tuning box will understand what the ECU is trying to achieve when operating in such a mode. In the same breath I do strongly advise against bypassing or removing the EGR (exhaust gas recirculation) valve in cars which are required to comply with the aforementioned standards.
Despite common belief, removing or bypassing the EGR will not result in excessive exhaust gas temperatures or engine operating temperatures in general. Some have asked whether engines were less reliable before the introduction of EGR systems. The short answer is yes, they were less reliable before the widescale intorduction of EGR systems.
Not as a result of the absence of an EGR valve though. Simply because engines of 25-30 years ago were generally less reliable than modern engines anyway. It's important to avoid confusing cause and effect with associative journalism.
In the case of DPF equipped diesel engines the EGR is crucial to the filter's regeration cycles. The objective is to get the exhaust gas temperatures high enough to burn off the soot which has accumulated in the DPF. Some systems employ heavy metal compound fuel borne catalyst additives to reduce the ignition temperature of the accumulated soot.
In my opinion, a well designed ECU remap will give a far better driving experience than any tuning box can currently offer. You will almost certainly avoid many of the medium/long term reliability problems which piggy backs or tuning boxes can create.
DISCLAIMER:-- *I do not work in the motor trade at all and therefore have no commercial grounds for saying this. Nor do I have any affiliation whatsoever, whether commercial, professional, or personal with any tuning company. I say simply for the benefit of anyone else is looking to persecute me for holding this opinion.
