Yes, i do need reassurance.......my V70 T5 Volvo was remapped and just got it done no problems but with a Merc. i just want to be sure it will do no great harm!
I love the motor to bits even though it is not new but almost bang on for condition, so i don`t really want to damage the engine if it can`t take the extra horses...
I simply don`t trust all these mappers that throw adverts everywhere and also sell tuning boxes that have to be turned down otherwise limp mode....i just want a few reports from C320CDI V6 engined owners that have had remaps.......
Being new to Mercedes i have just found out through my reading that a diesel badged C350 has the same engine as mine but is 261bhp so that is sort of telling me it may be ok to remap safely....
Understood. Well I ran my ML320 CDi for 40k with no issues and a friend brought the car off me, and has since got 80k further on it and still happy. Apart from the usual issues non have surfaced which can question the map.
I understand where you are coming from so let's go through the tuning world and give you some advice from all angles to see if this helps.
Firstly tuning boxes. What do they do? Well very simply a cheap tuning box is a simple pot which adjusts the voltage from the common rail sensor to fool the car that there is not enough fuel going into rail. As with diesel tuning the very simple way is, the more fuel that goes in the more power it will make (Very crudly described). There are some more expensive tuning boxes that can adapt at different points along a customised curve, and some others which go into your injectors and/or MAP sensor and some work well producing good power.
However, no-one can argue that a well calibrated remap to your car isn't better. But this opens a whole new box of worms.
There are numerous mapping companies out there who claim their maps are custom, but all they do is read a file, it's encrypted and sent off to their master tuner. The master then writes the file, encrypts the data and sends it back to the slave tuner. The slave tuner flashes the file in, doesn't know what is in there and gives car back to the customer. Which in practice works well if the master tuner actually understands the car, rather than simply percentage based increases across the board. 4% on boost, 25% on torque limiters, rail pressure 2-3% unless they are feeling brave etc. Effectively as generic as they come.
When tuning a car you need to develop and see how things react based on logs/dyno feedback etc. For instance as you say the 7G has a torque limit. So whacking 25% on the torque limiter is going to be 25% harder instantly under full throttle, and can effectively ruin the gearbox. However progressively bringing in the torque on the car is a nicer drive as well as being more mechanically sympathetic to the car.
For example on your engine I would not raise the torque massively below 2000rpm, except to smooth it out to get rid of the flat spot. Boost pressure I would be at maximum 1.52bar progressively built up and kept smooth.
I've seen some typical generic remaps on some late cars, such as the later 2012 C350 CDi engines with 265bhp, with fault code errors, broad percentage changes and using large amounts of boost to get the feeling or more boost. A proper calibration will use the correct amount of boost based on fuel/torque/drivers wish etc.
On this engine keeping it smooth, progressive torque delivery and the car will perform superbly well.
DPF removal if your car is fitted with one is no problem, as EGR removal.
On your car if it is the last of the W203 chassis then you should ideally want:
224bhp Standard - 260bhp Tuned
510nm Standard - 605nm Tuned
As with any diesel, it's all about the torque.
Hope that helps. Ask any questions
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