discovery 300tdi low topspeed

i have a 1995 discovery 1 300tdi we have removed the egr, had a new lift pump and the fuel pump turned up we have also had a new fuel filter and bypassed the sedimenter we have just put new turbo pipes on it and cleaned the intercooler out and it is quite nippy in 1st,2nd,3rd, and 4th but in fifth it is sluggish and it just reaches 65mph!!!! does anyone know why?

discovery94 said:

i have a 1995 discovery 1 300tdi we have removed the egr, had a new lift pump and the fuel pump turned up we have also had a new fuel filter and bypassed the sedimenter we have just put new turbo pipes on it and cleaned the intercooler out and it is quite nippy in 1st,2nd,3rd, and 4th but in fifth it is sluggish and it just reaches 65mph!!!! does anyone know why?

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Not really but there is a possibility that either the cam timing or the pump timing is slightly out. These cars will run even when the valves are hitting the pistons. The clue is broken or badly worn valve caps. When these cars are old a top speed of 65 is fairly common but what is it that causes the missing horses?

I know someone who used to be in a mobile maintenance team. They tried Discovery, Range Rover, Land Rover 110, Toyota Landcruiser, and Nissan Patrol. Allegedly the star performer was the Discovery which allegedly could do 90 to 95 but perhaps the speedo was optimistic. Their vehicle maintenance expert didn't think too much of the 300TDi engines and said that the cams used to wear down prematurely. Obviously if the valves aren't opening properly the performance won't be there. Another failing is allegedly clogged injectors. It is fairly easy to measure the valve lift. It can even be done with plasticine and a ruler. Good luck!