Drinking too much
beer in Munich ;)
Join Date: Feb 2012
Location: I would rather not say
I've been chatting to a few people who've used tuning boxes, particularly the fuel rail pressure offset type.
Nobody has found that the pressure is manipulated to a dangerous level or that there's been any engine damage. However most people agree with what's already been said so far here, that they apply a bulk solution to a problem which only sometimes exists, in a way which means it is also applied when it isn't required.
The crudeness of rail pressure manipulation comes in as a result of the fact that engine revs or load aren't even considered. Although pressure is proportional to load and revs there is nothing particularly artful about just adding more fuel through the rev range.
Other tuning devices intercept the injector signals. Good quality digital tuning boxes can distinguish between a pilot injection pulse and the main injection pulse. Toyota makes it's own injectpr tuning box which plugs straight onto the injectors for this very reason and it's known to be very good. At a cost of £3000 I suppose it should be.
Injector tuning gives the user the ability to tune the car for the latest conditions, which is probably of greatest interest to racers who want to alter the engine's performance with respect to the the particular circuit they'll be racing on.
From talking to the people who have first hand experience with different tuning boxes it's clear that the refinement of Toyota's injector tuning device gives the level of control which people who are interested in tuning for prevailing conditions can use to really good effect.
What has become clear is that the few people have tried to apply a similar level of refinement to fuel rail pressure manipulation by coupling it with rpm and load information have found they can make a very refined device. For example, everyone knows there is an issue with the torque curve of the 1.9JTDm engine between 1650 and 2300rpm (approx - when the turbo control changes from open loop to closed loop control and the VGT vanes are moved to the large turbo position) and something which removes that lull in acceleration just at that range of performance can be made using rail pressure manipulation based on dynamic rpm and load monitoring. It actually seems to become possible to draw your own torque curves in this way.....within sensible limits. It would never give the same level of ultimate torque that a remapping tuner can achieve by manipulating more parameters than just fuel rail pressure (which they already also do), but some people are attracted by the ability to gently tweak the torque delivery here and there for themselves in order to fine tune their cars basic performance.
Last edited by FixitSan; 05-01-13 at 14:36.