Hi everyone, first post here, was wondering if people could offer some advice about my 300tdi Defender 90. The engine has been totally reliable since I bought it about a year ago, and performs well at high revs - it'll sit at 70 all day on the motorway with forays to 75 for overtaking, and I've had it up to an indicated 80 - didn't have the nerve to go faster than that, but it seemed like it had some left to give. So it seems the engine is in rude health... and yet, it's SO sluggish in the lower part of the rev range. Now I know it needs the turbo boost to perform optimally and it's not going to be as nippy before that kicks in, but on a recent trip down to cornwall I was having real problems on hilly back roads. If I had a decent run-up at the hills and could keep the revs up, it would pull up them just fine in 3rd, but if I had to stop or slow down for any reason, it would barely be able to drag itself up in 1st or 2nd. One one occasion I started off on a moderately steep hill and simply couldn't get into 2nd - the engine would be screaming in 1st but every time I tried to whack it in 2nd it would be incapable of holding its speed, let alone accelerating, and would judder to a stop. I can't believe that this lack of power is normal without the turbo boost - even a N/A diesel must be able to get into 2nd gear on a hill, no? So my question is, since the turbo seems to be working when it cuts in, and since the power is fine for high-speed driving, what could be causing this lack of guts at the bottom end of the rev range? Can the turbo be adjusted to kick in lower? Is there anything else that could be causing the problem, which is then masked when the turbo is active? By the way the mileage is 167k, but the truck has been well serviced and had an easy life, it seems... any suggestions would be much appreciated!
300tdi very poor performance at low revs (only)
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Cutty Dyer
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Welcome to the forum - always nice to post a hello in the "Introduce Yourself" thread.
Could be injectors - filling the fuel filter with a concentrate injector cleaner made a noticeable difference to my 300tdi pre-boost performance.
Have you checked the valve clearances recently?
The pre-boost performance can be dramatically improved by turning up the "smoke" screw on the Bosch VE injector unit. The screw is located under a anti-tamper cap which is easily removed. Just undo the 13mm lock nut and turn the screw clockwise 1&1/2 turns (screw = 27mm torx from memory). I would only make this adjustment if you've exhausted all over possibilities (& make sure that it hasn't previously been adjusted).
There's a very good guide on this adjustment:
http://www.landroverweb.com/Pdf-files/Tuning_Land_Rover_Tdi_engines_Rev_2.pdf
EDIT:
I live on a very steep hill; just 1 & 1/2 turns of the smoke screw made a great improvement - in the mornings my 110 powers up the hill with ease & I can keep the engine revs right down (before the adjustment it would struggle to get going & require a lot of cold engine revs).
Could be injectors - filling the fuel filter with a concentrate injector cleaner made a noticeable difference to my 300tdi pre-boost performance.
Have you checked the valve clearances recently?
The pre-boost performance can be dramatically improved by turning up the "smoke" screw on the Bosch VE injector unit. The screw is located under a anti-tamper cap which is easily removed. Just undo the 13mm lock nut and turn the screw clockwise 1&1/2 turns (screw = 27mm torx from memory). I would only make this adjustment if you've exhausted all over possibilities (& make sure that it hasn't previously been adjusted).
There's a very good guide on this adjustment:
http://www.landroverweb.com/Pdf-files/Tuning_Land_Rover_Tdi_engines_Rev_2.pdf
EDIT:
I live on a very steep hill; just 1 & 1/2 turns of the smoke screw made a great improvement - in the mornings my 110 powers up the hill with ease & I can keep the engine revs right down (before the adjustment it would struggle to get going & require a lot of cold engine revs).
Last edited:
Thanks for the suggestions! I'll try those. In the meantime is there any possibility the turbo isn't licking in as early as it ought to, and could this be a symptom of a worn one? I don't have a boost guage or tachometer fitted so I'm not sure what revs it comes in at, but I'm guessing about 2k or not far below that. Is there any way to get it to boost lower in the range or are you talking an aftermarket variable geometry turbo for that?
Also could a worn or clogged intercooler be causing or contributing to the low pre-boost power?
Ps I'll post on the introduce yourself section too, thanks for the tip!
Also could a worn or clogged intercooler be causing or contributing to the low pre-boost power?
Ps I'll post on the introduce yourself section too, thanks for the tip!
storm99
Spreading Joy & Harmony
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Clean the intercooler and pipes out.
Thanks for the advice. Going to try all these suggestions (leaving the smoke screw til last, that is). Re valve clearances, no I haven't checked but will do when I get a chance. Would be great to get this sorted cos I can't fault the highway performance but it's a bit of a pig to drive around back roads, especially if there's any incline involved. Anyone have similar impressions with the tdi? I'm just wondering to what extent it's also just a trait of these engines. My dad's TD5 has a lot more punch lower in the range. But I can't believe this performance is 'normal' as even my 2286 petrol has more get up and go at low speeds!
