Hi all - my new (to me) 1999 Td5 Disco ES is very lovely in every way except for a lack of 'balls' or 'guts'.

It starts on the button with very little smoke, runs smoothly and generally seems happy except that acceleration is what I would describe as pedestrian.

Pulling away is painfully slow at times and it struggles to hold more than 70mph on the motorway. On some motorway hills it will slow to below 50mph with my foot flat to the floor.

Things that have been checked/done:

- MAF sensor unplugged, no noticeable change. (Reads 4.4 g/hr on Nanocom).
- MAP removed and cleaned, was quite black and gungey - very small improvement.
- AAP removed and cleaned, wasn't dirty, no change.
- Injector harness changed - no improvement.
- Checked for oil at red ECU plug - very small amount, cleaned with contact cleaner twice. No change.
- Checked intercooler pipes - they seem 'soft' compared to old Tdi ones but are sound with no splits or leaks.
- Checked turbo impeller for play - very little, normal amount.
- No EGR present (would a 99 have had one?)
- Will rev up to 4,750rpm/governer cleanly (perhaps a little reluctant but does get there).
- Turbo wastegate is free.

With my newly acquired Nanocom I have ascertained that the correct level of ambient air pressure (~100kPA) and manifold turbo pressure (~210kPA) are being registered, and the turbo wastegate actuator begins to open at around 160-180kPA with a reading of between 30-40%.

The only recurring error I get is 'EGR valve stuck open' which I presume has something to do with it being removed?

Any suggestions as to what I can try now? I'm at a loss really and would be overjoyed to be able to sort this and get it going properly!!

Hi, how old are the air and fuel filters though?...the fuel filter must be a good brand one

1. see the IAT(inlet air temp) reading... it should be very close to real ambient temp on cold start in the morning then as the engine warm up to +10 , max 30 degrees more than ambient depending on ambient temp, coolant temp and engine load

2. see how much the AAP drops when you floor it cos 100 is the default value the reading must be equal with real ambient pressure measured with barometer and converted in kPa and drop up to max 5 units under extreme load

3. the turbo hoses must not be soft cos if they are delaminated it'll be lack of power as 210 MAP is a bit low, you should get 230 under heavy load, better put new silicone ones cos they are not very expensive and it's something to be ruled out also the wastegate modulator even if it works it might not work as it should

4. is the FPR free of leaks? ... there is a small strainer under it in the head which must be clean as well... no fault code and lack of power can be a sign of low fuel pressure too cos that's not covered by diagnostics

5. compare the coolant temp(ECT) reading with the fuel temp(FT) reading, the FT should be around 10*C lower than the ECT at normal(around 90) ECT

these are my first ideas for now...come back with the results and we'll speak then
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One question - if the MAF sensor is reading very low on nanocom - but unplugging it makes only a very small improvement in performance, how likely is it that replacing it with a good quality one will cure my power issue?

answer in the other section where you asked