Isuzu Ute Range

Making a change like remapping the transmission in a brand-new car could potentially bring you undone come warranty time. If it is deemed those changes in any way contributed to the downfall of the transmission, even years later, the manufacturer might refuse your claim.

The best advice it to approach Isuzu to see if any running changes have been made to the transmission programming, as these would be factory changes and would not jeopardise your warranty. A jerky transmission is often cured by a new software package and car-makers often offer these at the next service. But going for an aftermarket re-tune or recalibration of the transmission is potentially asking for warranty hassles down the track.

What you’re experiencing is the front and rear axles fighting each other. Us old-timers call it axle wind-up and, as the name suggests, it’s what happens when the various wheels need to turn at different speeds, but can’t.

When you’re in 4H, you’re effectively driving the front and rear axles at precisely the same speed. Logic says this shouldn’t matter, but, depending on what lumps and bumps they’re covering at the time, there are times when the front and rear wheels need to travel at slightly different speeds. Throw in full steering lock, and you’ve just made things very difficult for the driveline with all sorts of competing forces being fed around the various tyres, axles and driveshafts.

This is far from limited to the Isuzu, and many four-wheel-drives without a centre differential (such as your D-Max) when driven at full lock in 4H will exhibit the same shunting and apparent loss of power. The power loss, meanwhile, is simply those front and rear tyres fighting each other; nothing to do with the engine at all.

When you shift back to two-wheel-drive (2H) the front and rear axles are suddenly free to turn at different speeds, and the sensation goes away. This whole situation is why you can’t use 4H on dry bitumen in a four-wheel-drive vehicle without a centre differential. Meantime, there’s no fix for it other than learning when and when not to engage 4H.

Any time a diesel engine produces black smoke, it’s doing so because too much fuel is entering the engine. The danger then is that the engine will start to run hot and that can cause all sorts of meltdowns. But combined with a knocking noise, black smoke can also signal serious internal engine damage.

The best advice is to not drive it any farther and get a diesel specialist to look at it. Diesel engines often make a knocking noise as a normal part of their operation, but if this noise has changed, then something’s wrong.