hi my missus car is at the garage they plugged it to the computer and told me that the turbo boost valve needs replacing(symptons car has no power), they changed it but still there, they said the turbo is fine, what else can they check to cause overboosting.thanks

 

If the car has no power, i'm guessing it isn't overboosting regardless of my lack of mechanical knowledge!

 

the car is a 4x4, so took it to a independant isuzu dealer that also selll range rover/discoveries etc, thats what they keep saying the turbo is fiine just overboosting causing the lack of power the car feels like in limp home mode.

 

Have they checked all the pipework to make sure there is no boost leak?

You normally feel overboost and then it goes into limp. If its driving with no turbo straight from the off, I suspect there will be a boost leak somewhere. A hose that has popped off around the intercooler tract or inlet manifold perhaps?

 

when u star from 1st gear it accelerates ok until u get to 50mph, then nothing

 

Did you try changing to second gear?

 

meant to saywhen you hit roughly 50mph so i use 1,2 and 3rd gear, not 1st gear in 50mph.