no throttle response The saga goes on.

[worane]

Yesterday the really great guys at Hunter & Cutthill Were kind enough to lend me an early td5 ecu to test against the loss of connectivity between throttle and ecu.
However I have found that it takes five to eight minutes for my fuel pump to stop operating on commencing a fuel purge . In other words I think it has a lack of fuel pressure at start up.
QUESTION. ...... Would this lack of pressure set off the M&S lights and give driver demand failures?
I feel it would be better to get an answer to this question before I pull the ECU for a swap and have to mess about recoding another and then doing it all again if it has to be reversed to give H&C their ECU back .
Any ideas?
Regards Nick.

[Pippin]

Hi Worane,

I do suspect a failed fuel pump, everything else is a red herring I think.

Nick

[sierrafery]

I really doubt that lack of pressure would throw a driver demand fault code though, the proper way of diagnosing this is like i said in your other thread IMO :

If you have nanocom see the throttle tracks(accel way) in the inputs fuelling menu, way(track) 1 should be around 0.8 at idle and way 2 around 4.2 then 1 should rise while 2 drop when you push the pedal as the sum of them to be equal with the supply all the time...if that's different there's a problem with the TPS inputs for some reason(wiring or ECU)....

The pump's operating time is managed by the ECU regardless of pressure cos there is no pressure sensor to monitor this so if you have a spare ECU it would be a good move to rule this out in the first place then chasing some more odd fault, also it's way easyer to swap the ECU than the pump...you need only to make the replacement ECU to learn the security code for testing porpose no need to code the injectors for that cos all you want to see is if if it gives you the same driver demand fault or not and if it does you can go further with the diagnose IMO, after a test like this you can't revert the ECU to it's previous setting cos any ECU will need security code learning when it's moved from one car to another so if the test fails you can give the ECU back and make it learn the security code of it's original donor car that's all

[worane]

Just how does it "learn the code?"

[sierrafery]

Plug in nanocom, go o Td5 - Utility - learn security code :

Learn security code: When the ignition is turned on, the BCU or Alarm, providing it is in
receipt of a valid transmitted Key Fob code and is therefore not in an alarmed or
immobilised state sends a coded data transmission to the TD5 ECU. The TD5 ECU then
decodes this data and compares the code contained in it against a mobilization code it
has stored in it. If the two codes compare OK, the TD5 will allow the engine to start.
This forms the basis of the immobiliser. If the TD5 ECU, the BCU, or the Alarm is
changed, it may be required for the TD5 ECU to re-learn a new mobilization code. This is
done by using this function to put the TD5 ECU into Security learn mode. After setting
the TD5 ECU into learn mode it is required to turn off the ignition for 15 seconds, then
back on. Receipt and acceptance of a valid code can be verified by viewing the
'Immobilisation Status' in the 'Other' section.
that's all you need to test the ECU, the injectior coding is important for how the engine runs under load not for other things so no need to do that now

[bob10]

Simple things first. Check the air bleed valve on your fuel filter




An air bleed valve is located in the bleed line connection. The valve comprises a restrictor and a membrane. The


restrictor has a small hole in its centre. This allows air and fuel to pass through the membrane. Air can pass through


the membrane, but once the membrane is wet with fuel it will not allow further fuel to pass through.


It's on the RAVE disc

[Jazzman]

I can confirm a fuel pump with poor pressure can most certainly give a driver demand fault. Mine was a fuel pump that has not quite failed yet and under throttle demand cannot produce the output it expects to see. Up hill was when i started to notice. It would hold speed in a freeway OK.

This happened to me in NSW on my way home from the Cape.

I had a fuel pump with me, changed it and problem was gone.

If you do change the fuel pump, you must change the fuel filter. Just trust me, not because it is a good idea anyway, or anything to do with warranty. It helps prevent the pump being noisy.

[sierrafery]

That's really interesting and good to know... though if that's the case i'm sure that the TP inputs on live data are OK which would rule out other faults

[worane]

Thanks for that Jazzman, that is the direction I was looking too.
I have acquired a fuel pump from a good friend who upgraded to a D3.
Today I will do the swap.
Silly thing is, the situation now is that you can drive 150 kms. and stop. Some times it will start (always does) and the throttle will be there OK. other times it is getting throttle on second start up. This is a lot better than when I started this post where it was taking MANY start ups to get the throttle to respond. Could it be a self healing Disco..... Naaah, Not in a Disco!
I have also bought a full set of injector washers and o rings to try as plan B.
I just don't want to have to go there just yet!
I will keep you all posted. Nick.

[Jazzman]

That's really interesting and good to know... though if that's the case i'm sure that the TP inputs on live data are OK which would rule out other faults

Yes. This is correct.

[Jazzman]

What exactly do you mean by throttle response? Does the throttle not do anything? There is a lot of lag time? Or perhaps the car is lacking power?

Surely if the throttle does nothing it is more likely to be the throttle itself or the wiring / voltage supply.

Just by the way, it is not easy to change the fuel pump. After you get the carpet out of the way it is realitily easy to undo all the fuel lines paying attention to the colour codes. But getting the new one in and screwed down can be difficult.

[Pippin]

TD5 Disco Fuel pump/sender unit - Land Rover Technical Archive - LR4x4 - The Land Rover Forum (http://forums.lr4x4.com/index.php'showtopic=54796) not if you look at this link which describes exactly how to remove and fit a pump in words and pictures. There is also another good link posted in the last few days that also describes how to remove the carpet and trim etc.

Nick

[Pippin]

This is it posted by Bohica:www.discovery2.co.uk / TD5 Fuel Pump replacement. (http://www.discovery2.co.uk/fuel_pump.html)

[Jazzman]

Thanks for the links. I've done it 3 times now. I guess i'd personally find swapping the ECU easier.

But either way, the fault finding is progressing. It doesn't really matter which he does first, I just hope for his sake he gets the right one the first time.

[worane]

Hi guys, I have done nothing to it today as the damn thing ran and went well with no loss of throttle , would you believe.
By no throttle response , I mean, put your foot on the pedal and get no response at all.
When I do get response it drives just fine.
Nick.

[sierrafery]

... I mean, put your foot on the pedal and get no response at all....

I'll be the most amazed guy here if that's the result of low fuel pressure... it'll be another specific LR oddity :cool:

[Pippin]

I must admit that I lean in your direction Sierrafery after Woranes last post.

[discorevy]

If there's no cavitation noises from the pump when the ign is turned on , check fuel pressure , if that's OK , check cam timing as I have twice had people that have done their own head gaskets and have had these symptoms, because of retarded valve timing , the last one would only give revs under certain conditions ( usually warm ) but also had a slow idle so check idle correction with nanocom. Driver demand faults were also logged , they can also log when an intercooler hose is off or with leaking inj o rings as well as previously mentioned fuel pressure issues.....and if the pump is making cavitation noises when ign on the look at inj washers

[worane]

I don't believe it but the bloody this is behaving it's self again today.( two days in a row)
I suspect it is because I now have a spare fuel pump and a set of injector washers and O rings! must have scared the hell out of it.
Time will tell. Going out for a day of flying tomorrow if the weather is good.
Nick.

[worane]

Still behaving!

[Bohica]

You've put the nanocom in the glovebox? :D

[LandyAndy]

Still behaving!
By any chance does this problem occur on rainy days?????
If so I would check for a leaky windscreen and corrosion on the actual pedal electronic mechanism and the connector.Check the contacts on the SLABS and BCU ecus behind the glovebox for water too.
Non genuine windscreens are shockers to seal in a D2;);););)
Andrew

[worane]

No rain is not the issue. We have had a really long dry spell here and it has only rained in the last couple of days so it is not the reason but thanks for the thought.