I have an Isuzu KB 280 D LE, 1997. The problem is that the speedo readind does not match the rav counter eg at 3000 RPM speed will be 115 and 130 km/ hr its close to 4000 RPMS or red zone on a flat road or downhill yet its got so much power uphill. What could be the problem and what can I do?
The reading would not be proportionally related, especially at high speed due to aerodynamics. The higher the speed, the higher wind resistance and that would result in more slipping of the torque converter thus the higher rpm.
Check the transmisison fluid level, if it is low, more slipping would be evident.