300tdi wont go beyond 2500rpm

I didn't think I had a problem with my 95' 300tdi Disco until I got a lift the other day from a guy with a 300tdi disco, in my Disco I set off in 1st and change up at about 2000rpm, same pretty much up through all the gears, mainly because at about 2500rpm it feels like a rev limiter cuts in, it sort of feels all choked up. I've always though they're all like this because performance wise it isn't bad, theres plenty of torque to enable you to change up early

But I noticed this other discovery was revving well beyond 3000rpm and sounded a lot happier about it than mine at 2500!

I'm puzzled as I've done all the usual, de-cat, de-egr, new filters, cleaned sedimentor, cleaned intercooler, changed hoses for silicon, replaced lift pump,tweaked the fuel pump, took the fan off,

Does changing up at 2000rpm and it dying off at 2500rpm sound about right, is this what everyone else's drives like? I don't know if this other guys was standard so it's hard to compare.

That doesn't sound sound right at all. Do you get alot of black smoke when it hits it limit?

Hi
Mine goes way up past 3500 revs no problem and probably a lot more if i felt abusive. I know sounds stupid check your throttle cable adjustments. maybe another fuel pump or air entering the system somewhere.

twice_nightly said:

I didn't think I had a problem with my 95' 300tdi Disco until I got a lift the other day from a guy with a 300tdi disco, in my Disco I set off in 1st and change up at about 2000rpm, same pretty much up through all the gears, mainly because at about 2500rpm it feels like a rev limiter cuts in, it sort of feels all choked up. I've always though they're all like this because performance wise it isn't bad, theres plenty of torque to enable you to change up early

But I noticed this other discovery was revving well beyond 3000rpm and sounded a lot happier about it than mine at 2500!

I'm puzzled as I've done all the usual, de-cat, de-egr, new filters, cleaned sedimentor, cleaned intercooler, changed hoses for silicon, replaced lift pump,tweaked the fuel pump, took the fan off,

Does changing up at 2000rpm and it dying off at 2500rpm sound about right, is this what everyone else's drives like? I don't know if this other guys was standard so it's hard to compare.

Click to expand...

No that’s not normal at all, just this morning on the way back from town I was coming up over a LONG steep hill, there is an overtaking lane on the way up. Minibus in front of me and some cars behind so I dropped into 4th, sat behind him for a moment and as the two lanes opened up I decked it. I was doing 70mph in 4th by the time I passed him which is about 3500rpm, and she was still pulling strong (I also wanted to see how she was performing - I always try and keep the revs as low as possible) then put her into 5th and kept the foot to the floor because a BMW tried to over take me too. NO chance, he couldn't drive it round corners.

If you have done everything else then it could be an injection pump problem with the governor system, or a restriction. Maybe you mis-tweaked it and turned the max speed down? They are all connected in as much as if you do say the maximum fuelling, you then need to tweak the low manifold pressure and boost fuelling etc or the whole system goes down the pot. Which is why I would never have a 300tdi engine someone had tweaked.

I had this on one of my old Lucas pumps, it needed new governor springs. Again, tweaking without parameters or test rigs can lead to internal components being compromised.

Could also be a fuel line restriction?

Thanks guys, food for thought. Seem like I've definitely a problem I never knew existed! I do get a bit of black smoke when I put my foot down, nothing too much though. And as for doing 70mph uphill mine doesn't do 70mph downhill !!!

Seriously what happens is as soon as you hit any kind of small incline the engine starts labouring and you loose speed.

One thing I did notice the other day was when I change up at say 2000rpm as soon I put my foot on the clutch the revs drop back to 1000rpm, so when you let the clutch out and change up you are never on boost and have to start all over again.

Will have a look for air in system and any blockage anywhere I think...

I had this same issue. Was blocked fuel lines due to running veg oil in the cold, also check your sedimenter behind rear wheel arch.

Or fecked lift pump? Or both?

Or restricted air flow?

Have you checked pump timing

check alternator , you get different gearing on alternators , this works your rev counter , Changed my Alternator and the one i put on has a different size pulley wheel thus alters rev counter reading as for power change filters

Check the intercooler pipes aswell. They might be delaminating.

You have enough to keep you busy there mate.
PS
Don't forget transparent fuel pipe for air check,

twice_nightly said:

One thing I did notice the other day was when I change up at say 2000rpm as soon I put my foot on the clutch the revs drop back to 1000rpm, so when you let the clutch out and change up you are never on boost and have to start all over again.

Click to expand...

That is quite normal, the engine will fall back to idle more or less during a gear change, you do want it to fall back anyway and if you are changing gears at a sensible speed then it should have the chance to do this (this will prolong the life of your gearbox).

When you bring the foot up on the clutch the engine speed will soon come up to the required RPM for the given road speed.

So if your trying to drive fast say during overtaking and don't want to lose much speed, thats when you carry on up the rev range to say 3000rpm in 4th which is 60mph, then when you go into 5th, your revs will fall back to 2400 which will still be on boost so you can keep accelerating, or just cruise.

I don't see what the problem is if you just change at 2000-2500rpm then what more do you want. I change mine at that point as well very rarely go above 3000rpm because mine does the same as yours. I'm happy with it though I don't want to go mess about as it will break something else (damn land rovers).

dannythedog said:

I don't see what the problem is if you just change at 2000-2500rpm then what more do you want. I change mine at that point as well very rarely go above 3000rpm because mine does the same as yours. I'm happy with it though I don't want to go mess about as it will break something else (damn land rovers).

Click to expand...

Max torque/power is at 1800rpms. You are not driving a f1 car rev the **** out of a diesel and you get death to a good motor. Why do you think there are rev limiter on lorry diesels and they do a million miles on a engine

Thor1950 said:

Max torque/power is at 1800rpms. You are not driving a f1 car rev the **** out of a diesel and you get death to a good motor. Why do you think there are rev limiter on lorry diesels and they do a million miles on a engine

Click to expand...

I can't agree more with you. I always shift gear as early as I can and don't like to rev my engine hard either, but like my overtaking at the weekend, I needed to let to climb up to 3000 odd and that probably is a sort of 6 or 7 times a year occurrence.

Diesel engines like to work hard not rev hard. But, something is wrong if he can't pull well up to 3000...

Thor1950 said:

Max torque/power is at 1800rpms. You are not driving a f1 car rev the **** out of a diesel and you get death to a good motor. Why do you think there are rev limiter on lorry diesels and they do a million miles on a engine

Click to expand...

discomania said:

I can't agree more with you. I always shift gear as early as I can and don't like to rev my engine hard either, but like my overtaking at the weekend, I needed to let to climb up to 3000 odd and that probably is a sort of 6 or 7 times a year occurrence.

Diesel engines like to work hard not rev hard. But, something is wrong if he can't pull well up to 3000...

Click to expand...

It is down to fuel and air, not getting enough.

First I would check/change air filter then fuel filter.

Check turbo hoses

Is inter cooler clean or the inside( full of oil) and outside fins full of mud etc.

Then check fuel pump in tank for out put at correct flow and output psi

What type of fuel is he burning

But it will be a process on elimination could be simple or could be expensive

Thanks guys for all the advice. I think it maybe a fuel blockage as suggested because bizarrely this morning for no reason it ran completely different, I mean it sounded quieter at tickover, it ran much smoother and it easily ran up to 3000rpm, in fact I even felt the turbo boost at one stage which was a novelty. Then coming home it was back to that strangled feeling and everything an effort, even tickover sounded different.

I'm not sure about treating a diesel gently is necessarily good for it, diesel lorries run to high mileage because they are serviced regularly and are properly maintained. My wife's BMW 330d feels like an f1 car when you're right up on the limit, I've driven it across Europe and the harder you pushed it the better it felt, back home on the shopping run it soon starts to feel sluggish. I accept though that a 16 year old 300tdi is somewhat different!