g400 loss of power

cafex wrote

Hello j walker,

In cases like yours', it is always a good idea by starting with fault code readings. You may ask your local M/benz dealer to give you a reading for which they will naturally charge. In my opinion, they should be charging in the region of 0.3 hr. to 0.5 hr. Labour to give you a reading. I have known some greedy Dealers charge out up to an hour for the same!

Alternately, go to a reputable independant M/benz specialist but, he need not, be a G-W agen expert, who has fault code reading equipment. If they have the "autologic kit", I would suggest going to them. I know that, this kit is very comprehensive and the close to M/benz equipment genericaly speaking. It was our company at that time, that supplied data to quite a few G-Wagens on their system, which included the newer G-series, the like of G500, 500G, etc...

Some times fault codes need to be erased, although the repair may have been effected, otherwise you could get a re-curring fault. Whilst not having access to the equipment, I would firstly, check the earth strap to the body. Poor contact here, has been known to cause similar faults to what you are suffering.

Without the fault code readers, you need a very experienced mecahnic and technical capable to test all types of sensorary equipment. Diagnoses has developed to a stage that just the test light and multi-meter can no longer be used on its own to do this type of work. One needs osiciliscopes and the like.

Once you have got some fault codes, it need not be everything on the list is faulty, this only gives you a narrowed down area to start investigations, once you have the codes, then start diagnoses of those possibly components. Effect your repairs, then get the code s to be erased and cross your fingers.

Regards,

The early (year 2000) G400 had problems with the pressure control valve. also worth checking the inlet temperature sensor and the operation of the throttle unit, near the intercooler. but could be many things and a diagnostic of the error codes is probably the best way forward.

There are many valves, pressure sensors, turbocharger electric guide-vane control, electronic accelerator pedal, fuel pump, fuel filter, fuel pump, temperature sensors etc.... any of which could be the problem.