Sluggish defender td5 90

Hi guys,

Just bought a defender td5 90, and she is being very sluggish now I understand defenders aren't built for speed and I don't expect it to be, but when I get to 50mph trying to get to 60 involves flooring the pedal and even then she just sits at 60 wont go any higher, search lots of different forums disconnected the MAF sensor thinking that might have affected it, seems to be running a little smoother but the exact same issure at 60,

Anyone got any ideas, now people ive spoken to said they easily can get to 70 and cruise at 70 in their TD5?

cheers in advance for the help

I've only just got my td5 too, but I've had 80 out of mine.
My wife's disco 3 went as flat as a fart a couple of months back and I tried changing man's etc to no avail. In the end I blanked the egr valves and now it runs fine

Strange, I can't understand it, was thinking of blanking the EGR but need to do the clutch master cylinder first, (first mechanical job ill be doing myself :S)

They can be slowed down by a dirty air filter or poor fuel supply too. Mine had a bit more pep after we changed the fuel pump earlier this year and will now go up hills in third that used to need second. As I'm sure you've seen on here, you might want to check the wastegate mechanism moves freely. Possibly the fuel pressure regulator is getting slack and letting the fuel back into the tank at less than 60 psi. The injectors only have tiny little holes in them so unless the fuel is at full pressure at the engine they're not going to pick up a full charge to squirt into the cylinder, especially when they're rattling up and down 30 or 40 times a second.

Ive changed the fuel filter yesterday, going to clean Map sensor tomorrow, Will also do air filter at the weekend, as for the rest I understood none of it (im a novice, what's is all the mentioned and how do I check them?) pics would be amazing!

not sure on the td5,but my 300 had similar problems only yesterday and the locking nut on the throttle had slipped,went from 60 flat out on the m way to 90+without trying but i think the pumps been played with,one extreme to another

See if you can get a nanocom/hawkeye plugged in and see if there are any faults. Post up if there are any.... To see tach, air conditioning, and ABS faults are normal (if you don't have any of those).

Check the red plug to the ECU (under the drivers seat), for oil. If there's oil in it; clean it with electrical/brake cleaner. If that is also true, change the injector harness. Actually if you just purchased it... Add this to your list of things to do.

If it runs better with the MAF unplugged; get a new VDO MAF. Unplugged and better running means it's bad.

Look around the FPR (fuel pressure regulator); under the intake, side of the TD5. Look for leaks, as they will do that over time.

Has the air filter been recently changed?

Check for any leaks or cracks in your turbo pipes.

Maybe pull the tank (or cut an access hatch in the tub; I did this... HIGHLY recommend it) and check for sludge in the bottom of the tank. Driving it will kick up the sludge and block the fuel pump screen.

How do I check for sludge in the bottom of the fuel tank and how easy is it to do? I am a novice and have limited tools currently, pics would be much appreciated for all the above things to do, thanks for the advice so far

I once got to 85 in my 300tdi.

Problem is, I live at 93.


Ba dum tish.

Siphon as much fuel out as you can first! In the defender TD5 the fuel tank sits on a kind of tray behind the back axle. This is attached to brackets on the underside of the chassis rails with bolts in captive nuts that are apt to liberate themselves when you try to undo the bolts. That way, in theory the tray can be dropped, and so can the tank, so you can get at the pump. What a lot of people do is cut a hole in the floor of the rear tub to access the pump. The Discovery boot floor has a little hatch in it already, right from the factory, but they never gave you one on a Defender for some reason. There are a few threads on here with suggestions of where to cut. If you do so, be careful as the tank is very close to the boot floor, so it would be really easy to hit it with a drill or jig saw blade, and as it's plastic (OK, it's thick plastic, but it's still plastic) it would be very easy to damage. The pump and fuel gauge sender unit is a big cylindrical thing held in by a collar that can be unscrewed. There's a special tool for this but most of us get by by tapping it round with a suitable drift on the notches. The pump unit is spring loaded so it can come out with quite a jolt. Hey presto, you're in the tank. When I did this to mine I discovered that the plastic mesh at the bottom of the pump unit was covered with what appeared to be grass clippings. The TD5 likes a free flow of fuel at maximum pressure, so any restriction here can impede performance.

That's my quick story. You'd probably be better off checking the manual for the exact procedure, but that's roughly how it's done.

Hey guys cheers for the replies so far today ive cleaned the map sensor, free'd up the turbo wastegate, I had a look at the injector harness the plug under the bonnet seems to be some oil there so will be changing when I get a chance, went for a test drive she seems to be running better MAF sensor turns out to be okay, runs the same both plugged in and unplugged but the engine just seems like its working far to hard at 65mph pedal on the floor she starts jumping and vibrating almost like the engine is working far to hard, any ideas or is it still going to be a case of fuel tank put a new pump in ect?

With your engine running the same when MAF sensor is plugged in or unplugged would suggest an issue with the MAF sensor.
I had a similar issue with TD5 running the same when MAF unplugged and plugged in and I did take some convincing that MAF was at fault but when I changed it (for an original LR part) the engine ran better. Now if I unplug the MAF sensor engine performance drops restored when plugged back in.

If the engine runs the same with the MAF unit disconnected, then the MAF unit is defective.
In this case the engine management unit will run a default map, and will not deliver the optimum performance.
Fit a new MAF unit.