TD5 15mpg?

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Freelander1banger

Active Member
Posts
111
Location
South England
As per the title my td5 seems to do shockingly bad on a run, roughly getting about 15mpg using the pump to measure it out.

This is sitting at 70 with cruise control on, its on 265/70/16s, winch bumper, light bar, and snorkel.

Its had new injector washers/seals, injector loom, stage 2 storm tuning map, egr blank, and just had the manifold skimmed and refitted as it had warped.

Maf is mapped out

any ideas? injectors? FPR? temp sensors? i was going to re do the timing to begin with.. but it seems very low, and I cant think of something that would cause that
 
Tyre dia v speedo reading accuracy?

Quick google suggests 26/70/16 i.5 inch dia larger than 255/55/18 which is a massive 5.1 percent!
 
Freelander1banger said:
thats taken into account for the mpg, not to sound rude but ive read a dozen threads that are 90% people arguing how they got their mpg figure, only answers on possible causes please
Click to expand...

Manual/auto/rooff rack/spot lights bars etc, anything that will cripple air flow?

My d3 pretty much does 20mpg everywhere, a run gives 25mpg.
Last td5 wasnt much better 22 and run 27.

Fuel figure easy to work out and theres only one accurate way and thats fill up to fill up, none of this 20quid gives me x miles rollacks.

Wont be long before some wise arse says get a v8!
 
lynall said:
Manual/auto/rooff rack/spot lights bars etc, anything that will cripple air flow?

My d3 pretty much does 20mpg everywhere, a run gives 25mpg.
Last td5 wasnt much better 22 and run 27.

Fuel figure easy to work out and theres only one accurate way and thats fill up to fill up, none of this 20quid gives me x miles rollacks.

Wont be long before some wise arse says get a v8!
Click to expand...

Manual, no roof rack just a full length roof mounted light bat, winch on the winch bumper but still a fair amount of flow, it struggled to maintain 70 up a hill before the map so I'm wondering if that could be linked, turbo actuator is free and working
 
Freelander1banger said:
Manual, no roof rack just a full length roof mounted light bat, winch on the winch bumper but still a fair amount of flow, it struggled to maintain 70 up a hill before the map so I'm wondering if that could be linked, turbo actuator is free and working
Click to expand...


That rings a bell, my td5 was chipped/larger cooler/boost controller etc, then started to gradually lose power, wasnt convinced at first but yes it was down and struggled at higher speeds until it even got flat at lower speeds in the end it was the sensor thats bolted to the inlet manifold, boost pressure/intake temp I think, wasnt that dear genuine and LR dealer had it on the shelf which kind of tells you all you need to know!
Iirc I removed pretty much all the tuning goodies as convinced they were at fault, but it was even worse in std tune.
 
lynall said:
Manual/auto/rooff rack/spot lights bars etc, anything that will cripple air flow?

My d3 pretty much does 20mpg everywhere, a run gives 25mpg.
Last td5 wasnt much better 22 and run 27.

Fuel figure easy to work out and theres only one accurate way and thats fill up to fill up, none of this 20quid gives me x miles rollacks.

Wont be long before some wise arse says get a v8!
Click to expand...
Nuff said
 
If you have mapped out the MAF I assume the engine is using the MAP for fuelling data. Have you checked cleaned the MAP? You could also have a turbo problem and the extra fuel is being used by the extra throttle being used to compensate.

I would start with comparing live data from the MAF and the MAP (hopefully your MAF still works!). If you don't have a suitable diagnostic then the Foxwell NT530 with Jag Land Rover software is a cheap option that works well on the TD5 and it captures live data very well. Full throttle up a hill you should be seeing close to 650 (air flow, but cannot remember what the metrics are) from the MAF if the turbo is delivering properly. If the air is all getting to the intake manifold then you should be seeing close to 230 (pressure) at the MAP. If a lot less than 650, there is a turbo issue. If you have 650 but not 230 then you are losing air somewhere between the two. Check hose connections, check hoses for splits or internal collapse, maybe even clean out the intercooler and check it for leaks.
 
lynall said:
That rings a bell, my td5 was chipped/larger cooler/boost controller etc, then started to gradually lose power, wasnt convinced at first but yes it was down and struggled at higher speeds until it even got flat at lower speeds in the end it was the sensor thats bolted to the inlet manifold, boost pressure/intake temp I think, wasnt that dear genuine and LR dealer had it on the shelf which kind of tells you all you need to know!
Iirc I removed pretty much all the tuning goodies as convinced they were at fault, but it was even worse in std tune.
Click to expand...

the map sensor was changed with one of my mates defender when it was stock and didn’t make a difference, but it’s only a £40 part so Ill call LR today and get one, can’t hurt
 
Si Click said:
If you have mapped out the MAF I assume the engine is using the MAP for fuelling data. Have you checked cleaned the MAP? You could also have a turbo problem and the extra fuel is being used by the extra throttle being used to compensate.

I would start with comparing live data from the MAF and the MAP (hopefully your MAF still works!). If you don't have a suitable diagnostic then the Foxwell NT530 with Jag Land Rover software is a cheap option that works well on the TD5 and it captures live data very well. Full throttle up a hill you should be seeing close to 650 (air flow, but cannot remember what the metrics are) from the MAF if the turbo is delivering properly. If the air is all getting to the intake manifold then you should be seeing close to 230 (pressure) at the MAP. If a lot less than 650, there is a turbo issue. If you have 650 but not 230 then you are losing air somewhere between the two. Check hose connections, check hoses for splits or internal collapse, maybe even clean out the intercooler and check it for leaks.
Click to expand...
Maf was brand new when it was stock as the map was my bodge to a underpowered vehicle, but the map was reading around 30 psi absolute with the turbo played with, but the tuner did say all fuelingcis not calculated off this one sensor, so a new one makes sense.

can the timing make much difference to fuel economy? I did it already but I remember not being able to get it exactly bang on as I forgot to let off chain tension, but it was pretty damn close
 
A brand new aftermarket MAF can be a problem itself in a 15p engine. But that should be irrelevant if you have mapped it out. You seem focused upon sensor performance, so I would clean the MAP, but then check the live data in order to rule out a turbo or air leak problem. I assume you have checked the connections to the wastegate control valve?
 
I found that mine was overboosting (air flow too high), so fitted a new genuine MAF and tightened the rod, much better and a little less fuel

Check your boost
 
I think I’ve the issue, I was thinking about it was when I installed the snorkel and did the 2nd trip to strata I noticed the range decrease (pre-mapped) so I’ve disconnected the inlet from the air box went on a run and for the first time ever I hit 100mph with ease, it feels slightly more alive, so atm I’m guessing it’s the ill- fitting snorkel as it’s the eBay cheap one, but I was always able to hit peak boost according to my live read out. I’m going to leave it off since I’m only doing motorway runs in it for a while and see if my mileage increases as I suspect it will
 
You should also see the real coolant temp reading cos the gauge goes to the middle at 70*C and if the thermostat is blocked open and the viscous fan locked the ECT won't exceed 80*C and that would increase the consumption cos the optimal consumption is at 90-92*C. Also at the wheels and tuning you have you need a EGT gauge cos high consumption means high EGT too which will kill the engine on a long run. To find the cause you need a run with a diagnostic tool hooked to record live data otherwise it's a guessing game
 
For what it's worth, my TD5 Defender seems very susceptible to anything that increases the air drag. If i have the roof rack on, even if I'm not carrying anything, it takes a bit off the top speed. It's not a very aerodynamic shape to start with, so I was surprised it made such a difference. A snorkel would have a similar effect. Also, it does like to be able to breathe freely. As the air filter reaches the end of its design life it becomes smokier and a little less sprightly, so I put a new air filter in before the MOT. Again, increasing the length of the inlet tract with a snorkel would very likely have the same effect.
 
Brown said:
For what it's worth, my TD5 Defender seems very susceptible to anything that increases the air drag. If i have the roof rack on, even if I'm not carrying anything, it takes a bit off the top speed. It's not a very aerodynamic shape to start with, so I was surprised it made such a difference. A snorkel would have a similar effect. Also, it does like to be able to breathe freely. As the air filter reaches the end of its design life it becomes smokier and a little less sprightly, so I put a new air filter in before the MOT. Again, increasing the length of the inlet tract with a snorkel would very likely have the same effect.
Click to expand...

my snorkel is still fitted, I’ve just pulled the maf out the air box so it’s unrestricted, so far it seems it’s gone back to normal, but that’s a very rough guess using the gauge. I’ve just brimmed her, so I’ll drive it for a few days, fill it up and work out the MPG, then reconnect, and work it out again just to make sure it’s not a fluke.

if it is the snorkel I’ll have to enlarge the inlet in the wing as that’s the bottle neck.

I’m also going to fit a new FPR, mine drops below 4 bar when measuring head pressure while revving, the new regulator is only £20 since mine doesn’t leak I don’t see the need for a new unit, but a few others on other forums noticed an increase in fuel efficiency after replacing it so worth a go for an easy ish job

I also checked my live read outs inlet temp was as expected, coolant temp is 190/200f so bang on 92c really. Boost is at 30psi absolute so again as expected, eveything looks good there. Just a shame the d2 EMS is so lacking compared to most vehicles
 
Brown said:
For what it's worth, my TD5 Defender seems very susceptible to anything that increases the air drag. If i have the roof rack on, even if I'm not carrying anything, it takes a bit off the top speed. It's not a very aerodynamic shape to start with, so I was surprised it made such a difference. A snorkel would have a similar effect. Also, it does like to be able to breathe freely. As the air filter reaches the end of its design life it becomes smokier and a little less sprightly, so I put a new air filter in before the MOT. Again, increasing the length of the inlet tract with a snorkel would very likely have the same effect.
Click to expand...
Even on a not very aerodynamic shape, anything that sticks up above the smooth surfaces will create turbulences and reduce smooth airflow even further.
I think this was one of the reasons that as Land Rovers got faster, the ribs on the outside of the roof became ribs on the inside of the roof.
All matters of drag only become a noticeable factor above about 50 mph.
Hence, on a vehicle that is used a lot on motorways and A roads, snorkels, roof racks, winches, etc. will have a surprising impact on fuel consumption.
Around Town, or on country lanes, they probably won't make much difference.
 
A fuel pressure regulator for £20 sounds a little too good to be true - perilously close to the Britpart side of things. Unless you mean the repair kit.
Once the engine is running, the fuel pressure itself isn't too critical on a TD5. If you unplug the fuel pump it'll keep going, albeit at slightly lower revs. I haven't dared drive around like this though, in case it breaks down in a difficult position, so can't comment on the fuel consumption. But it'll certainly run OK.
 
Brown said:
A fuel pressure regulator for £20 sounds a little too good to be true - perilously close to the Britpart side of things. Unless you mean the repair kit.
Once the engine is running, the fuel pressure itself isn't too critical on a TD5. If you unplug the fuel pump it'll keep going, albeit at slightly lower revs. I haven't dared drive around like this though, in case it breaks down in a difficult position, so can't comment on the fuel consumption. But it'll certainly run OK.
Click to expand...

yeah just the actual regulator seals and gasket, not the whole valve block. Mine does run fine, others just said it made their td5 become a lot more responsive and better on fuel, so I thought I’d try it for the sake of £20
 
Our TD5 is very sensitive to speed on a motorway.
I had to drive 550 miles mostly on M ways recently and went no faster than 55, for a different reason. The fuel consumption dropped right down. even the difference between 60 and 70 will cost you at the pump.
But 15 mpg is ridiculous.
+1^^^ As others have said re wind resistance, plus, if you have to use a snorkel, which way is the top end facing?
Apparently that can make a difference too.
Best of luck sorting it.:)
 
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