Langers

Langers

Well-Known Member
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
 
Thanks Sierrafery, that info is helpful to even those of us whose Td5's are running well.

I'd first though stick an SD card in your Nanocom and record data during a run when the problems are happening and graph it out. It could be that a sensor is going bad and the ECU is compensating for it by reducing fuel. My guess is that you (or we) may be able to see the issue on the graphs of data. As an example, if your temp sender was going bad, your gauge won't necessarily move (a "feature" of the Td5) but the ECU will reduce fueling/power.

In addition to what Sierrafery says, I would be looking at flushing your intercooler. That's a routine maintenance item for the Td5 IIRC, and at that age it's pretty guaranteed to be dirty inside which would reduce its efficiency. Although this obviously would mostly affect higher RPM/load situations. Does it accelerate ok from stopped? Can you feel the turbo kick in?

Also if your MAF is showing 4.4 when its plugged in, then it's bad. And although the engine will run decently without it, I've found it certainly runs better with a good, OEM-spec (Siemens) one. Avoid the Chinese knockoffs.

I don't think a '99 would have a catalytic converter either, and the fact that you're hitting decent boost levels would mean air is flowing in and out decently well, but that's a culprit sometimes too.

Overall easiest thing to do is to look at the data. After that it'll be getting dirty. Let us know how you get on.
 
sierrafery said:
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
Click to expand...

Cheers for the reply!

1 - IAT seems to be about right, begins to rise when the underbonnet temperature starts to rise. Up to about 35.

2 - AAP only drops by 1-2 units at full chat.

3 - Bypassed the wastegate modulator (pipe straight from intercooler piping to wastegate actuator) - little to no change, except MAP is now reading slightly lower, approx 209.

4 - Not noticed any leaks. How is best/easiest to check fuel pressure?

5 - Coolant temp runs between 88-90, fuel temp approx 79. So this all checks out.

Any further thoughts? :confused:
 
isn't the wastegate rod stuck? ... only way to measure fuel pressure is to insert a gauge instead of the FT sensor in the FPR
 
sierrafery said:
isn't the wastegate rod stuck? ... only way to measure fuel pressure is to insert a gauge instead of the FT sensor in the FPR
Click to expand...

Stuck? How do you mean? I can move it with a pair of grips, quite a strong spring action but it does move.

And any pointers on the thread/type of fitting the gauge would require?
 
by the way, if you'll go with a gauge in the FPR leave the FT sensor connected to it's plug to not get open circuit fault code on it while you watch the pressure cos it might be hard to start... you must get 4 bar there
 
I had this problem with a 2001 110 td5 that I bought a few years ago. Absolutely flat as a fart would'nt even pull in 5th on the motorway. First thing I did was buy a NNN ECU off a mate with a stage one boost, absolutely transformed the vehicle !

I have had other TD5's and have never to do this, fuel pressure regulator leaking would'nt cause this! I would start with air filter or snorkel if there is one that might be blocked, turbo pipes colasped but you usualy get black smoke.

Blocked diesel filter or the filter on the bottom of the tank pump but they are a bit of a tw@t to get out.

1999 would have a EGR valve when new !

Good luck !
 
Jason2 said:
I had this problem with a 2001 110 td5 that I bought a few years ago. Absolutely flat as a fart would'nt even pull in 5th on the motorway. First thing I did was buy a NNN ECU off a mate with a stage one boost, absolutely transformed the vehicle !

I have had other TD5's and have never to do this, fuel pressure regulator leaking would'nt cause this! I would start with air filter or snorkel if there is one that might be blocked, turbo pipes colasped but you usualy get black smoke.

Blocked diesel filter or the filter on the bottom of the tank pump but they are a bit of a tw@t to get out.

1999 would have a EGR valve when new !

Good luck !
Click to expand...

Cheers - wonder what was wrong with your original ECU then? Because surely it should have been a lot better than that as standard if working correctly?

To be honest I am half considering chucking it into Alive or someone for them to sort it out, I'm losing inspiration with it now after fitting a new fuel pump today for it to have no effect :confused:
 
Langers said:
Cheers - wonder what was wrong with your original ECU then? Because surely it should have been a lot better than that as standard if working correctly?

To be honest I am half considering chucking it into Alive or someone for them to sort it out, I'm losing inspiration with it now after fitting a new fuel pump today for it to have no effect :confused:
Click to expand...

Sorry to hear that matey ! Only other things I did were the usual filter changes and nanocom was saying that the MAF was ferked so I changed that too.
 
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?
 
very likely cos with good MAF it should run better than in error default mode(open circuit with it unplugged) where the MAF reading is a fix preset value for the ECM
 
Last edited:
sierrafery said:
very likely cos with good MAF it should run better than in error default mode(open circuit with it unplugged) where the MAF reading is a fix preset value for the ECM
Click to expand...

Well, MAF replaced this afternoon with no improvement. Readings on nanocom now should a healthy sensor though, 55g/hr at idle rising to 550-600 at full chat. Doing my nut in!! :Cry::wtf:
 
Fuel filter and also filter mesh on the bottom of the fuel pump.
As already said you really need to check for good flow and pressure.
Just because the pump runs does not mean it is developing good pressure.

Langers said:
Fitted a new FPR yesterday but forgot to check the little gauze filter, will check that later. Any other problem areas for fuel supply?
Click to expand...
 
Shifty1962 said:
Fuel filter and also filter mesh on the bottom of the fuel pump.
As already said you really need to check for good flow and pressure.
Just because the pump runs does not mean it is developing good pressure.
Click to expand...

Fuel filter is a new MANN one, should be OK?
Fuel pump including mesh is new. Since the problem is exactly the same as before fitting a new pump and FPR, I am assuming that fuel pressure isn't an issue, but could be wrong. Also removed the FPR again today and thoroughly cleaned the gauze filter behind it - was dirty/clogged but no improvement.

Another point to note is that the turbo shaft has a fair bit of play side to side and a small amount in and out. Nanocom reads about 190-200 kPA max boost, and shortening the wastegate actuator doesn't seem to do anything. Could it be replacement turbo time?
 
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