Disco TD5 Problem

greenpilot

Hi Guys,

I have a 2002 disco TD5, and all was well untill I have recently noticed slight erratic trottle behaviour and once, loss of power. If i accellerate, and them ease off on the trottle, the engine braking really kicks in in a jumpy fashion, as if it torques down too rapidly-not smoothly as it should. Also, a couple of times, while accelerating through 2200/2300 rpm, at the point where the turbo should kick in, it doesnt...the power just pegs on that rpm and goes no further. I had to pull in and switch off the engine, and back on again to reset the ecu.......Then all was fine. Otherwise, a great machine.

Any thoughts???

Thanks,

Paul

101sean

Could be several things, oil in the injector loom, throttle pot playing up, failing MAF sensor, dirty IAT/IAP sensor or failing fuel pump. Doubt if it's a sticking wastegate as the problem isn't consistent.

First choice would be oil in the loom, design was changed post 01 to stop it but it still happens :rolleyes: Locate the ECU under the bonnet and pull the red plug off and see if there's signs of engine oil. If there is, clean the plug and ecu socket with brake cleaner or similar solvent and see if that improves things. You'll need to change the injector loom, straightforward and costs around €50, the red plug will need cleaning for a couple of weeks after until the oil stops coming through.

If there's no oil, pull the plug off the MAF sensor (between air cleaner and turbo) and see if it drives much better. If it does, you need a new MAF sensor, only buy a genuine one, around €90. MAF failure usually means loss of performance and won't rev over 3000, your problem seems more variable.

The other faults require plugging in to diagnostic equipment to check.

Whereabouts are you located?

greenpilot

Hi,

Im in westport. I ran a diog test, and all came up OK. I will check for the oil in the loom tomorrow. I wonder does the ECU need a remap or reset??
Thanks for the quick reply.
Paul

101sean

No, it works or doesn't, not much in between, if the ECU is dead then normally you will see 'Topside Switch Failure'.

You're sorted if you have diagnostic gear, you can check things like throttle tracks with it but I'm betting it's oil in the loom.

If not, here's how to diagnose the MAF from the UK's Td5 genius (Porny on most of the LR forums :rolleyes:) -

It does come up on the diagnostics - you've just got to know what you are looking for. Just looking at the Fault Codes is only part of using diagnostics.

A Td5 MAF sensor typically fails in two ways -

1) It goes dead completely and returns a value of 0kg/hr to the ECU. The ECU logs this as fault, and adds it to the fault code list.

2) The more common way a MAF fails is to return a value of 4 kg/hr to the ECU. Because it's not 0 kg/hr, the ECU does not see it as a fault - so it does not add anything to the fault code list. This is where most dealers and quite a few independants seem to fall down.

You need to check the live date values - with the engine running. If at idle you see 4kg/hr your MAF is dead (and the one effect is the poor starting and lack of throttle response as mentioned). At idle a MAF should read betweem 52 and 60 Kg/hr (depends if you have a genuine part MAF or a cheap copy).


There is a 3rd common failure mode I see quite often, which is worse with cheap copy MAF sensors...

When you out driving you should see 525 + Kg/hr (standard, not remapped) when under load and making it rev a bit. I've seen quite a few MAF sensors max out at between 250 and 400 Kg/hr - which results in a very flat TD5 as the MAF sensor is telling the engine it's not seeing that much air, so the ECU matches air flow to the fuelling.

The other issue is 'failing' MAF sensors, which at idle give a value of 20 - 30 Kg/hr at idle - again the lower air flow value results in poor low end performance, but the off set from what it should be at idle gets multiplied at top end, so the max air flow the MAF believes it is seeing is actually lower than it should be - again affecting performance.

The MAF (Mass Air Flow) sensor is located at the clean out outlet side of the air filter... and is connected to the pipe that goes down to the inlet of the turbo.

OldGuysRule

Had a similar problem on my 01 td5, it appears to have been the fuel pump failing, following replacement, all seems well.

Caddyvanman

As above Fuel Pump on the way out !