Having your engine “chipped” for a power gain is bit like playing rugby: you have a lot of fun taking part, but you cannot avoid suffering some physical damage in the long run.
The engine fun starts when you go with your mates to watch a mechanic spend a couple of hours with your car, a chassis dynamometer, a laptop and a programmable chip. He fine-tunes the fuel mixture and spark timing at various loads and throttle openings to force the engine to develop more power and torque than its maker intended.
The next stage commences when you and your mates drive around town at ridiculous speeds to show how exciting the car has now become. The final stage is when you accompany your car behind a tow truck to a workshop because something has broken…
My good friend Haker Fourie, who manages a small hotel, used to be very good in the scrum before his body packed in, and he has the ears to prove it. He recently started to play the chipping game, and progressed quite quickly to the final stage. He was lucky, because his 2009 Nissan X-Trail 2,0 dCi 4×2 did not need a towin. It was still drivable, but the transmission was making an ominous clunking noise. It was at its worst at low speeds but was less noticeable higher up.
Syd took the car for a spin and said he suspected there might be some broken parts in the clutch mechanism but this model has a layout that he was not familiar with, including a dual-mass flywheel This consists of two flywheels that are joined together with a spigot and a set of springs in such a way that the flywheel attached to the crankshaft is able to vibrate with the crank. The second flywheel accepts the drive via the springs and carries a clutch unit. He was in unfamiliar territory, and ’phoned Henry, an acquaintance who works on Nissans.
Henry confirmed that the first flywheel is in constant motion whenever the engine speed is low enough, because it oscillates some millimetres with respect to the second flywheel as it copes with a diesel engine’s massive torsional vibration. As the engine speed increases the vibrations die down and so does the oscillation.
When Henry heard that the Nissan’s engine had been chipped, he had no hesitation in saying that the extra torque had weakened the dual-mass control springs, thus causing the transmission noise. He said these units do not take kindly to any form of abuse, and the complete dual-mass unit and clutch needed to be replaced. His workshop would charge about R23 000 for the job. Haker was visibly shaken when I gave him the bad news and started to mumble something about warranty, so I had to tell him that manufacturers’ warranties do not cover any modifications.
I then decided to see if there wasn’t some alternative solution. I ’phoned the manager of a workshop that specialises in drivetrain repairs and discovered that it fixed these units in one of two ways, depending on the owner’s bank balance. They said they would replace the complete dual-mass or substitute a regular single flywheel and clutch from another Nissan model that just bolts on. Total cost, R11 000.
If the latter option is chosen there will be some drivetrain vibration at low engine speeds, but experience has shown that if these speeds are avoided this fix should be robust. We explained the technicalities to Haker and he chose the less complicated solution.