300tdi struggling to pass 70mph

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barney66

Member
Posts
12
Location
Telford
Hi, I have a 300tdi defender 90 with a disco transfer box and it pulls well up to 60mph and slow after that and wont go past 70mph unless downhill.

Here are some details about it,

compressions 400psi on all cylinders checked lift pump plenty off diesel flow while cranking, cleaned intercooler,good hoses, boost reads 1.1 at manifold accelerating, never burns oil, recon injectors around 1500 miles ago, no brakes binding, clutch fine, no middle box, all new genuine fuel and air filters, fuel tank clean Texaco premium diesel, lift pump gauze clean, new timing belt and solid bottom belt pulley, pump timing set with a dial gauge at 1.54mm lift at tdc, tyres are 31x10.5x15s, speed is accurate with a sat nav.

Any ideas please ? I am now stuck for any ideas of what it could be, if I tweak the pump any more I get black smoke and high Egts, I have the madman ems2 engine monitoring system fitted so alarms for egt, coolant temp, oil pressure and coolant level,
Thanks in advance,

barney
 
Trewey said:
Why is that a problem?
Click to expand...

Which bit ? if you mean 70mph tis only a problem because surely with the defender box it should easily do this and it doesn't plus it slows on hills.

Don't get me wrong, I am not looking for a sports car, I have had a series for 10 years and this for 6 years but more of my journeys go on motorway now and you struggle to pass anything that's doing just under 70mph
 
barney66 said:
Hi, I have a 300tdi defender 90 with a disco transfer box and it pulls well up to 60mph and slow after that and wont go past 70mph unless downhill.

Here are some details about it,

compressions 400psi on all cylinders checked lift pump plenty off diesel flow while cranking, cleaned intercooler,good hoses, boost reads 1.1 at manifold accelerating, never burns oil, recon injectors around 1500 miles ago, no brakes binding, clutch fine, no middle box, all new genuine fuel and air filters, fuel tank clean Texaco premium diesel, lift pump gauze clean, new timing belt and solid bottom belt pulley, pump timing set with a dial gauge at 1.54mm lift at tdc, tyres are 31x10.5x15s, speed is accurate with a sat nav.

Any ideas please ? I am now stuck for any ideas of what it could be, if I tweak the pump any more I get black smoke and high Egts, I have the madman ems2 engine monitoring system fitted so alarms for egt, coolant temp, oil pressure and coolant level,
Thanks in advance,

barney
Click to expand...

70mph in a 300tdi 90?! :eek:

How long do you think it would take you to stop if you did hit 70mph?

Not something I'd like to try. 55 - 60 is plenty for mine!
 
Chr1s said:
70mph in a 300tdi 90?! :eek:

How long do you think it would take you to stop if you did hit 70mph?

Not something I'd like to try. 55 - 60 is plenty for mine!
Click to expand...

Not long, new vented genuine discs and calipers on front, new servo, brakes are good and I don't travel close to the person in front, I don't do this on A and B roads it is on the motorway.
 
My 200tdi 110 happily sits at 70 on the motorway, afaik nothings been done to it.

And how's it any different driving a Landie or say a Transit at 70?
 
Have you tried with the landy stationary and the engine switched OFF getting someone to hold the accelerator pedal all the way down and seeing if the linkage on the fuel pump is going all the way to the stop screw to the left of the accelerator linkage, could be the stop screw is screwed in too far stopping the accelerator linkage to go far enough and won't rev anymore or the accelerator linkage could be fitted in the wrong position on the pump so when the pedal is pressed all the way the linkage on the fuel pump is not toughing the stop screw on the fuel pump, hope this helps :)
 
Another thing to try is making sure the bulkhead is nice and tight / not rotten as if the bulkhead is loose / moving or flexing when being driven that can cause the problem aswell, just a thought :)
 
cornish rattler said:
Another thing to try is making sure the bulkhead is nice and tight / not rotten as if the bulkhead is loose / moving or flexing when being driven that can cause the problem aswell, just a thought :)
Click to expand...

no rot in my bulkhead and hits the stop screw on the pump both me and my mate have checked this, like I said previous it produces the boost at the manifold just over 1 bar and can get the black smoke and egt but no more go,
Thanks for trying
 
harry2012 said:
My 200tdi 110 happily sits at 70 on the motorway, afaik nothings been done to it.

And how's it any different driving a Landie or say a Transit at 70?
Click to expand...

Agreed, My 110, Original 200 tdi with nothing done to it will cruise at 70 MPH all day. Its recently done a 19 hour trip each way from France to southern Spain and back cruising at 70 mph and heavily loaded.
 
My 90 will sit comfortably at indicated 70mph on a light throttle and has some in hand to accelerate and overtake. (unmodified)
Have you checked engine rpm at full throttle? are you sure about final drive ratio's ? Tyre size? If ratios have been altered you might just be running out of usable engine speed if ratios are too low. :boom:
 
smbaker said:
My 90 will sit comfortably at indicated 70mph on a light throttle and has some in hand to accelerate and overtake. (unmodified)
Have you checked engine rpm at full throttle? are you sure about final drive ratio's ? Tyre size? If ratios have been altered you might just be running out of usable engine speed if ratios are too low. :boom:
Click to expand...
No I don't know rpm at full throttle I don't have a rev counter, but it is a disco box and you can tell it lacks power as its getting up there, clutch isn't slipping as its not revving, checked fuel pump plenty coming out the connection where it connects to the pump when cranking , fuel is there as it produces smoke, tyres are as I stated 31x10.5x15 which I think is same rolling diameter as the standard ones.

I was wondering could this be a problem with the fuel injection pump, like I said plenty of power low down pulls pretty well up to 60mph with little smoke unless you got your foot flat down, starts well hot or cold

Thanks again
 
barney66 said:
No I don't know rpm at full throttle I don't have a rev counter, but it is a disco box and you can tell it lacks power as its getting up there, clutch isn't slipping as its not revving, checked fuel pump plenty coming out the connection where it connects to the pump when cranking , fuel is there as it produces smoke, tyres are as I stated 31x10.5x15 which I think is same rolling diameter as the standard ones.

I was wondering could this be a problem with the fuel injection pump, like I said plenty of power low down pulls pretty well up to 60mph with little smoke unless you got your foot flat down, starts well hot or cold

Thanks again
Click to expand...
Might sound silly, but have you tried a new fuel filter and air filter?
 
Yeah, it should definitely go faster than that, I got 80 chasing some guys with td5s a while ago in mine and that was going uphill. They kept accelerating when they got to 80 and I didn't, but it kept up valiantly up until that point!
 
mikescuba said:
Might sound silly, but have you tried a new fuel filter and air filter?
Click to expand...
Yes those are genuine and only a few weeks old, I have had them off again since to check plus the gauze out of the pump, all were clean, even had the pick up out the tank no gauze on that but tank is spotless inside,

Thanks again
 
barney66 said:
no rot in my bulkhead and hits the stop screw on the pump both me and my mate have checked this, like I said previous it produces the boost at the manifold just over 1 bar and can get the black smoke and egt but no more go,
Thanks for trying
Click to expand...

Just seams strange as i have had 300tdi disco's that will top 80mph and my currant 1988 2.5td ( defender 200tdi ) with 265 special track's just fitted, tweaked pump and straight through exhaust max's out at 85ish mph using satnav, not sure really :confused:
 
It's got me now, run out of ideas, what sort of egt,s are you all getting over 70, that's my big worry if I keep my foot in it it will go a bit more but egt,s go over 700c so I back off
 
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