Automatic 300TDI low on power but otherwise running fine. What to check?

[JamesO]

Hi guys,


I've recently ended up with my dad's Land Rover Discovery 1 300tdi Automatic (so has EDC pump rather than manual pump). The vehicle starts first time with the smallest puff of smoke, idles fine, and doesn't have any check engine lights. When driving it's smooth, no smoke from the exhaust, and no issues other than it being very slow, even for an auto 300TDI. When he bought it at the end of 2019 I drove it home a few hundred KM's for him and found it quite acceptable on power even compared to my V8. It would happily run up to 130-140kmh without too much struggle for overtaking and never felt like I was in danger of not having enough power at intersections to pull out. Now that I've taken over it as he's moved overseas it's intolerably slow. I'm talking 0-100kmh in around 25 seconds with properly inflated tyres, and struggles to make it past 110-115kmh. I don't know when it lost its power, if it was sudden or gradual since I'm not the one who drove it the last year and half.


I'm going to dive into it this weekend hopefully to figure out what's going on and was hoping for some recommendations or things to check? This will be the first time I've ever worked on a diesel so please be kind I don't know all the terms!


Cheers,
James

[edddo]

Given that it ran quite well not long ago it might be as simple as split or delaminated turbo hoses. Also worth checking the throttle throw to ensure it is free to full throttle.
Has it had any recent work done?

[JamesO]

I would have thought a split turbo pipe would cause black smoke given that there would be too much fuel available for the amount of air getting through. Or does it reduce fuel by some mechanism if there's a boost leak? It's recently had a new (used) transmission installed, but it was down on power before I replaced that so I assume it's unrelated.

[Fattima]

Check the sedimenter and fuel filter, mine was full of crap when I got it and valve clearances were way out.

[Blknight.aus]

Check the sedimenter and fuel filter, mine was full of crap when I got it and valve clearances were way out.

fuel lines filters and the lift pump need to be checked out first, if the delivery to the pump falls off the power falls off as well.

[workingonit]

...things to check?

When looking at the turbo outlet area you will see the main pipe to the intercooler, and harder to see, two small diameter pipes.

One of those small pipes goes around the back of the engine to the injector pump and seems to me to help proportion fuel to air flow. Most of that pipe is tough plastic (ABS?), However, it is joined to the turbo body by a very short piece of rubber pipe. The rubber perishes over time. When working in that area the pipe is easy to break as is the plastic barb connector. With that fault the vehicle runs up to cruise speed at a snails pace. From experience...