Mitsubishi Sedan Range

It definitely could be the transmission’s main pump. Without this pump working properly, it can’t create the pressure necessary to select gears via the valve-body or indeed, produce enough drive force to actually get the car to move.

But, you could also be looking at a broken valve body, faulty selector cable from the cabin to the transmission, a broken torque converter or a complete, catastrophic internal failure of the gearbox. Instead of guessing, take it to a transmission specialist who is very likely to have seen this very problem many times before.

This is definitely not the sort of information car makers publish. Instinct suggests the headliner should, indeed, fit through one of the door openings, as that’s how it would be fitted on the production line. Try a front door opening first with the front seat slid all the way back and the backrest laid right down.

The other option would be to politely ask a motor trimmer how they manage this job.

Some of these east-west mounted V6s can be very difficult to access the rear bank of cylinders. A quality workshop manual will detail how to remove the rear rocker cover and spark plugs, and there are also some very good online tutorials you can tap into.

The fact that no error codes have been logged suggests that the spark plugs are at fault. In some cases, on-board computers can detect a bad ignition lead or coil, but will not recognise a dud spark plug. But oil leaks can also cause misfires if the oil gets into contact with the leads or spark plug contacts, too, so the leaks need to be fixed as well. The spark plug theory is also supported by the fact that the miss is occurring under load, which is when an ignition system is working its hardest.