View Full Version : Tunit box v chip
Hello everybody.
I`m new to diesel tuning, could somebody please explain the difference
between the tunit box/module and a chip change/remap.
Tunit say that they do not increase boost and that chip remaps can only achieve more power by boost increases, which shorten turbo life.
I spoke to Tunit at Autosport earlier this month.
TDi Tuning is 99% about fuelling. it's just how you go about it that makes the difference.
a chip can do it across the rev range, some chips will just multiply up by say 20%.
you do need to increase boost slightly, but it's hardly any %age wise (unlike petrol cars)
This has been discussed at some length in the TDI forum - worth a search.
Boxes are a crude (but effective) method of increasing power. They basically intercept the signal from the ECU to the injectors and hold them open for longer than the ECU intended. More fuel = more power, and this indirectly increases boost pressure due to the extra exhaust gasses moving through the system.... this extra boost means more power, and more exhaust gases... It takes a long time to read, but it happens much faster in reality ~ net results is more fuel and more boost.
Remaps replace the standard ECU Programme. They have a whole new "map" of fueling and boost accross the rev range. One big advantage is that they can open the injectors before the standard programme - a couple of degrees more "advance" if you like. This is good, because diesels smoke if you're injecting more fuel than can burn.
Remaps add extra fuel (compared to std) at the start and the end of the injection cycle. Boxes can only add extra at the end.
Remaps are therefore technically superior, but can't be unplugged in a few mins. "Un-Plug" is of prime importance to some so they go with a box, although almost all remaps are very "stealthy".
Is the tunit just a resistor like the cheap boxes?
They for sure don`t claim 180 bhp and 300 ftlbs (or more) for the PD 130 as claimed by the Jabba/Revo remaps yet costs about the same:confused:
FabiaTDi
24-01-2004, 10:15
On my last car I had the Tunit fitted for a while and although the power increase was very noticable, it was nowhere near as smooth as the Jabba remap that was done later on. Power and torque output were better than the Tunit.
Considering the Tunit is switchable between all PD engined cars, It can't be as good as a specific remap for an individual engine. Having said this the tunits can be adjusted, but not sure of the variables that can be changed etc..
Now, I would go for a remap every time. It depends if you want the removable advantages of the Tunit etc...
:wink2:
Originally posted by Slark
Is the tunit just a resistor like the cheap boxes?
They for sure don`t claim 180 bhp and 300 ftlbs (or more) for the PD 130 as claimed by the Jabba/Revo remaps yet costs about the same:confused:
No it's not a cheap resistor. As m0rk mentions most of the tuning on diesels is solely fueling. Most of the boxes are also wired to the maf sensor to up the boost abit.
Since boost is only slightly incremented, with all the extra fuel your getting in diesel with boxes produce much more soot than chipped/remapped diesels.
As mik mentions you can change when fueling begins as well as boost with a chip/remap.
Originally posted by prc
Most of the boxes are also wired to the maf sensor to up the boost abit.
ohh is this true? how does it do that though the maf?
Originally posted by sssstew
ohh is this true? how does it do that though the maf?
I have to check, but I was told that indirectly (via the MAF reading) an slight increase in boost was possible.