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SA4x4 Clinic got a technical query



Question by: Antonio Barone Answer by: Arnold VenterI own an ‘03 Nissan Patrol 3.0 TDI GRX. I bought the vehicle about two and a half years ago with approximately 18 000 km on the clock. My driving style is very tame and I’m always trying to get the most out of a full tank.
To further improve the Patrol’s fuel consumption I had a performance chip fitted, and the catalytic converter removed. My thinking was simple: the more power I’ve got the lighter I can be on the throttle.
I was particularly hoping for more low-down torque to lessen the effects of turbo lag, but unfortunately I have yet to experience any performance increase. The workshop that performed the installation also detuned the vehicle’s boost control as I was experiencing overboost, which caused the Patrol to lose power if the engine speed was kept at a constant rev for four to eight minutes, resetting again if the throttle was released.
The boost problem is now solved but I now need to depress the throttle a lot more and the Nissan seems to lack power. I’d like to know two things: was the Dastek chip the wrong choice for my vehicle and is the overboost now set too low?
Antonio Barone

A Unichip is like a piece of raw steak: it has the potential to taste excellent but it depends on who’s doing the cooking. The point I’m trying to make is that performance chips are seldom faulty or incorrectly matched to an engine; it’s more likely that the person programming the chip has done a poor job.
It sounds to me like your Dastek performance chip was mapped incorrectly, possibly too rich. Unfortunately, by detuning the boost the guys that installed your Unichip have made matters worse because there’s now even more fuel and less air entering the system.
I would have the Unichip remapped at a different engine tuner, preferably one that specialises in diesel motors. Visit to find a Unichip dealer or tuner near you.
Arnold Venter
CRD (4×4 fitment & repairs)
(011) 907 0580 /