Hi Trevor
You havn't said which engine is fitted to your 400 but here's my advice anyway. I'm assuming that timing etc is all OK ie if it's got a belt that it's been fitted properly.
First most obvious check is that you're getting maximum fuel at full throttle. Get someone to push their foot to the floor on the throttle pedal, then check that the lever on the pump is touching the stop.
If that's OK and it's a fairly old higher mileage engine you can try adjusting the fuel screw on the injection pump. It will usually only need adjusting a half a turn but will transform the performance. If you turn it too much then you'll produce black smoke and have trouble passing your next MOT. It would be best if you marked the screw so that you can put it back to where it was if you have any problems.
Most mechanics won't touch these screws but if you're careful it will make a huge difference to your low down pulling power. I have tweaked a diesel RangeRover and a Discovery like this and they both still fly through the MOT on smoke.
One word of warning. You need to make sure that you're turning the right screw and may have to break a seal to do it. I would suggest you speak to your local friendly diesel specialist who should be able to tell you which screw and which way to turn it.
Good Luck
Graham, June 2008
