Tuning technology for diesel engine vehicles


In 2004 I had to do something, I had bought a New Hyundai Tucson 2.0 CRTD CDX powered by a 1991 Common Rail Diesel engine and the fuel consumption was awful and I found out on line that I was not alone in this predicament and no-one at Hyundai really wanted to know.


I began researching tuning technology and found that in Germany there were companies that had produced a Diesel Tuning box suitable for any Hyundai diesel vehicle powered by the common rail engine.


Looking into possibilities of tuning the vehicle for Economy and also a Power and Torque increase to aid my towing capacity I found that to have your ECU programmed by a specialist is rather expensive and it can be seen that the ECU has been adapted by engineers and it may cause you warranty to be voided.


Doing this research I found that there was a thing called a Common Rail Tuning box that was produced in Germany and it seemed to promise all of the things that I wanted for my Hyundai to achieve, and at a modest cost yet not have the problem of warranty cancellation.


After some further research which included visiting numerous web sites specialising in tuning and asking loads of searching questions of knowledgeable people I decided to purchase a to see if what was promised on the website could be attained.

For me this was a plunge into the unknown and quite daring as I have always left what’s under the bonnet alone.

I found the unit to be of assistance and did tell others of my purchase; as a result many other diesel vehicle owners also purchased one.


I found out that Hyundai might possibly cancel the warranty on my vehicle if they thought for one minute that this Tuning box had caused my Hyundai to breakdown and necessitate warranty repairs. It is therefore better if it is removed prior to a visit to the dealer for servicing - by the way it didn’t breakdown or need any warranty repairs.

I have also learned that some insurers do not like any form of vehicle tuning no matter what it is being done for, Economy, Better Torque or indeed extra Power when out driving with or without a Caravan on tow.

An Insurer will / may impose extra costs if the addition of a Tuning box is notified to them. (I cannot say don’t tell them but informing them or not is up to you)

I did find that once fitted the Tuning box gave me a more responsive vehicle and a hesitation lag on acceleration had gone, the fuel consumption did improved from 29mpg to 34.9Mpg (with Caravan 25 /27.5 Mpg) and the torque increase really helped with its towing power.


Now roll time on to 2008.


I had purchased a New Hyundai with a Euro IV 2.0 litre diesel engine. The price of fuel had increased then increased consistently to levels previously unheard of, although Hyundai had improved the engine and it’s fuel consumption I did think that perhaps it would be possible to obtain an improved C R Tuning box too.


This time I found it a bit easier to research and I contacted ASA Autotechnik Saretz, a company specialising in Diesel tuning products in Germany, to see what they were offering for modern Hyundai Diesel vehicles.


The company ASA Autotechnik Saretz produce an ASA ECO CR Tuning box for Hyundai vehicles and it looked quite promising on paper, I contacted them and obtained a Tuning box so that I could perform a serious road trial using it and then produce an unbiased report on the product for members of the web based forums. This may then assist forum members in making a decision whether to purchase a Tuning box in order to improve their diesel vehicles performance and / or fuel economy.

What a Tuning box does it modifies the electronic signals that are being relayed to the Electronic Control Unit (ECU) that controls the injection timing; the Tuning box has been programmed by tuning experts to provide the optimum performance from a diesel engine.


The Tuning box does not override or alter the original ECU settings, and the additional range of power provided is within the safe operating characteristics and performance parameters of your engine.

The Tuning box cannot harm your engine and any damage caused is going to be due to the vehicle operator and their method of driving. 

There can be modest gains in speed, the manufacturer confirms that the additional speed gain is 6%. The red line of the RPM range in top gear sometimes governs the limit of extra speed. This effective increase in power and torque produced by the engine is due to the Tuning box programming. The overall effect is that you need less Rpms to get the same power you get if the Tuning box is not fitted. If your vehicle is driven in a normal manner (you know what I mean - not driven like a madman) there can also be an increase in the vehicles fuel economy of around 3-6 mpg. (Maybe more-See in the report The Trials below)

This fuel economy gain is made in the lower to mid speed ranges and I was able to see this quite clearly for myself during the trials. The Tuning box can also be adjusted to personal preferences and I tried this out to see what would happen. (See in the report The Trials below)

All of the genuine Hyundai data including the Hyundai alarm system data are totally unaffected by the installation of a Tuning box and it’s diagnostics are not detected by the ECU, as does not report on the Tuning box addition to the vehicle.

The ASA ECO CR Tuning box arrived very quickly by recorded mail from Autotechnik Saretz and having signed for it I opened the package and saw impressive well-made aluminium cased Tuning box and the electronic connection cable that was provided was a good length to make it easier to fit the Tuning box to a secure area in the engine compartment.

 There was also accompanying documentation containing directions how to connect the Tuning box to the vehicle. The document also explained how the Tuning box could be easily adjusted to suit the vehicle owner preferences. I adjusted the Tuning box to the first position as described and began the trial. (I did think that these instructions could have been better) It took me less than 15 minutes to fit the Tuning box to my vehicle and although I knew it would fire up I checked that the engine started before I closed the bonnet.


The Trials


So resetting my on board computer after refuelling my vehicle I left home, taking it steady at first (Necessary as I was in a restricted 30mph zone) to get the feel of my vehicles response to this ASA ECO CR Tuning box. I pressed down on the accelerator and immediately the engine felt more responsive, more powerful and smooth.

I must admit that I really started to smile; I am no technician but my vehicle was driving along so well and with no hesitation, as It pulled away from the traffic lights and I pressed down on the accelerator the feeling of extra power was immediate and the smile turned into a grin. (All this from such a little Tuning box –wow)


I drove along a mixture of roads, travelling along minor local roads to the A road and then on to the Motorway, now the trials had started in earnest, the road conditions varied between rain, more rain and then some sun and dry roads and my object was to see how the Tuning box performed so I kept my speed to just below the national speed limit travelling on the motorways between 65 to 70 mph.




It became obvious that I only needed to use only a light pressure on the accelerator as I could feel that my vehicle responding quickly as I accelerated. The increase in torque and power were readily apparent and my vehicles engine sounded or seemed to sound smoother. I overtook vehicles with ease and on the odd occasion mistakenly (if you know what I mean) let it go over the 70mph limit by a smidgeon or two when passing slow moving trucks or cars.


I had reset my on board computer and Refuelled my vehicle before setting off and now returning home and parking up on the driveway I noted that the mileage covered was 126 miles and the vehicles computer indicated a figure of 38.7 mpg overall during this initial trial.


Next time out was for the weekly trip to the supermarket for the weeks shopping and driving locally for 18 miles return trip saw the same smile on my face but the fuel consumption was considerably higher, local roads and fairly heavy traffic conditions plus roadwork’s saw the computer register a miserly 29.9 mpg still hopefully better things to come.


It was a Saturday the weather had improved and it was sunny and the temperatures were heading upwards so a trip to the coast seemed to be a great idea. To get there I decided to take a scenic route along both A and B roads, a leisurely drive was planned and the computer trip was set in readiness for the journey. For the first 9 miles or so traffic was heavy but travelling along at around 45-50 mph glancing at the computer I and slowly (much to my annoyance I must admit) saw it was registering 35.6 mpg and then annoyingly some idiot had decided that on this day a main A route would be closed on my side to facilitate road works and a diversion was in place and that’s where we started to queue for the next 40 minutes moving so slowly that an elderly cyclist even passed me. By the time I reached the end of that road and got back on track my computer was reading 30.7 Grrrr. Finally arriving at the coastal car park I checked the computer and was pleased to see that it had moved to 39.1 and that was pleasing.


What I did find at this first setting (quarter to nine position) was that I had to use my gearbox more than usual as the engine didn’t like me going down to really low speeds 28mph-30mph in a high gear then pushing the accelerator down without choosing a lower gear, it seemed to push me into choosing a lower gear before I could progress properly. I suppose really I was at fault not having the right gear at low speeds but I was checking to see what could be done with the Tuning box plumbed in.


So before setting off back home I adjusted the Tuning box setting (to 10 to 4) and reset the computer.


It became immediately apparent once I set off that my vehicle was really more responsive than on the journey down to the coast at the previous setting, I was amazed that and even the lightest of touches to the accelerator pedal produced an immediate response from the engine and the speed picked up very quickly.


To travel home from the South Coast I had to use the Major A3 road, although this particular route has moderately heavy traffic it flows exceedingly well but it does undulate quite a bit from the Portsmouth area it has some very steep hills that take you past the Queen Elizabeth Country Park and then to Petersfield and beyond, but the performance of my vehicle with the Tuning box attached making the necessary electronic requirements for the engine it seemed inspired.

On my arrival on the driveway I was really dumfounded as my computer red 43.6 mpg (a double wow)


Now after a few small local trips to small local towns in a radius of about 12 / 15miles from home I found that the vehicle still responded exceedingly well to the throttle but petrol consumption was lower and figures of 33 to 34 mpg were more common. I suppose that all things considered local trips involve more stopping, starting, queuing and road workings and the lower figure was to be expected from my 2.0 litre diesel. (Although I plan to try some other adjustments to the Tuning box later. (Turning a small screw makes the adjustments)


Where I was able to use a Motorway I found that by maintaining around 60 mph the fuel consumption improved tremendously and once when I found myself on the road during commuting time with extremely heavy traffic I skipped using the motorway and drove home via the A road as my top speed was 50 at best and I fully expected the fuel computer to be low on my arrival home but I was pleasantly surprised by a reading of 41.7 mpg overall for this relatively short round trip.


Towing trial


I hitched up the caravan, as it’s ready loaded for our next trip when the weather improves everything was correct for a normal tow. I decided to take the caravan on a round trip up along the M3 for 15 miles then back towards home using the A30 and then local twisty roads and home again total mileage of around 35 miles or so.


Started off as normal and within seconds I was travelling along at 30mph, the extra power and torque left me in no doubt that I really should have no problems, negotiating the minor roads and stopping twice for traffic lights then it was full speed ahead (well the legal limit of 60 anyway) along the M3 where I found the Tuning box really came into its own as I just had to push down on the throttle and speed increased quickly and without hesitation, it seemed so powerful and responsive.


I did some overtaking along the way, as lorries seemed to be going slower than normal on the inclines (well slower than I was travelling anyway) so I passed a few, admittedly one at 72 mph. I had no problems with towing and almost forgot the caravan on more than one occasion. (Which I put down to my age!)


Leaving the Motorway and returning via the A30, I found travelling within speed limits very easy and a couple of times even looked in the rear view mirror to make sure the caravan was still attached as my vehicle was completing the task with ease. (It is that memory thing again) Having negotiated some fairly steep hill conditions and also some really winding roads I arrived home, my vehicles computer read 27.6 mpg overall and I felt the tuning box had acquitted itself very well.


Summing up and the final assessment


I am not a technical person but I have now been trialling this ASA ECO CR Tuning box produced by ASA Autotechnik Saretz for a fair period, in varying weather conditions. My only thought was to compare it to another that I currently own to see if a product could be improved on and also changed from my original supplier.  I can definitely say that I felt that the Tuning box was all that the company said it would be, and for me it offered an improvement over my current Tuning box.


ASA Autotechnik Saretz promised increased Torque and Power and that is what I definitely received, they promised fuel savings if the vehicle is driven modestly in the low to mid speed ranges and I found that there was an improvement, especially when I maintained consistent speeds on motorways or fairly clear ‘A’ roads. Travelling at distances of around 12 miles with a light accelerator use also saw mpg gains but they were smaller mainly due to the fact that the fuel returns are better if the engine is really warm and at optimum speeds.


I completed 315 miles overall, and filled up with 44 litres of fuel, therefore overall I got a creditable 32.50 Mpg and as this trial was inclusive of a caravan tow, short journeys, long journeys etc I feel the ASA ECO CR Tuning box produced by ASA Autotechnik Saretz was a success. I intend in the future to change the settings of the Tuning box to see if this makes any further improvements to fuel consumption or power and torque gains.


I do believe that this Tuning box is better than my previous one. The performance has brought a smile to my face as the Tuning box appears to make my vehicle perform better, and the program setting from the manufacturers seem well balanced.


I end by saying that should you be considering the purchase of an ASA ECO CR Tuning box then this is definitely one that will satisfy your requirements. The product produced by ASA Autotechnik Saretz has a 2-year warranty, is modestly priced and will make sure you smile as you enjoy your driving.


ASA Autotechnik Saretz have a tuning box for all Hyundai diesel vehicles (plus other diesels too), if you do decide you would like one then remember to tell them you want it supplied with the correct connection cable for your vehicle. (Details of the type can be found alongside the listing for the unit on their web site)





A really special price to forum members has been negotiated with ASA Autotechnik Saretz who can offer a Tuning box, plus appropriate connecting cable complete and delivered to your door for an all-inclusive Special price of  € 99 plus shipping costs of  €10 to the UK. (A total of  €109)

Members in other Countries should check shipping costs prior to purchasing but I have been advised that they will be as reasonable as is possible)


Please Note: -

This is a considerable saving on the regular ASA Autotechnik Saretz Internet price of €148 plus postage.


This is the best available offer on the Internet. Contact them by Email to order at




When ordering please quote reference Itza/ASA ECO CR/Special Offer


If you have another vehicle that has any other type of diesel engine, ASA Autotechnik Saretz possibly manufacture a tuning device for that as well so contact them to see what they can offer you.