Disco 2 Auto Disco II cranks but will not start 3 Amigo's + M&S flashing!

Got the same set of figures - not exactly the same but all in the same area - with or without the MAF connected. Not sure if it is me or hopeful thinking but the crank to throttle authority time seems to be reducing. The engine is still ' cold' so I would expect some delay as it changes from starting map to running map. Only if driving could I be certain that the changes we are effecting are having any effect.

Concerned about the Nanocom in that several times it comes up blank figures until I unplug and reconnect with ignition on. There is also a new window on boot up complaining about 'no firmware'. I did have a 64G SD card in it but it complains of having no SD card. I did try to initialise it on my old laptop which is still running Microsoft OP. The speed from which it recorded a 'disc initialised' was far too quick. I am planning to get a much smaller SD card soon!

Neptune19522 said:

Got the same set of figures - not exactly the same but all in the same area - with or without the MAF connected.

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Then the MAF is fubar and it takes some time for the ECU to recognise that and go to default hence the delay in the throttle response

Neptune19522 said:

The engine is still ' cold' so I would expect some delay as it changes from starting map to running map.

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there is no such thing

If it is a 15P get a genuine LR MAF not an aftermarket one

Took the MAF off and could not see any problems. Checked the circuit with my DVM and got what I was expecting. I then reinstalled it and found that the connector may have been poorly inserted - last person, before your requested test, to remove it was the RAC chap! No identifiable improvement although the figures were better that the first test we carried out. I am assuming that 'fubar' is a euphemism for 'failed'. Before I pay over £80 for a new component I think I need to test it out some more. Do you have any actual figures for the MAF sensor?

Also the Mil light was flashing! Extinguished upon engine starting but a worrying light. Nanocom reported no faults after the engine ran and stop.

Neptune19522 said:

Took the MAF off and could not see any problems. Checked the circuit with my DVM and got what I was expecting. I then reinstalled it and found that the connector may have been poorly inserted - last person, before your requested test, to remove it was the RAC chap! No identifiable improvement although the figures were better that the first test we carried out. I am assuming that 'fubar' is a euphemism for 'failed'. Before I pay over £80 for a new component I think I need to test it out some more. Do you have any actual figures for the MAF sensor?

Also the Mil light was flashing! Extinguished upon engine starting but a worrying light. Nanocom reported no faults after the engine ran and stop.

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What absolutely does my head in is that you would expect a diagnostic bit of kit to tell you everything like "your MAF is Naff" but it doesn't. Not saying it is the kit's fault it just seems to be that LR hasn't bit the bullet and got the ECU/ECM/BCU and all the other little pooters to report each and every fault properly. To me a diagnostic should be part of the car, a screen on the dash or somesuch that tells you all the info you need to know. Not some "Black Magic Box" that only garages and people like us have to get hold of, install and try to work with. Sure, of course, it would put the price up a bit, but in the great scheme of things I could forgo the odd cupholder, heated seat, etc etc in its place!!
As far as your issue is concerned, I don't know if the Nano would pick it up, but is your MAP/Iat sensor nice and clean? I found I had similar issues to yours when mine was dirty. But I have the earlier 10p engine.

In a nutshell:


*** AAT is not displayed

Not sure what engine I have beyond it is a TD5. Have no idea what is the difference between 10P and 15P is!

Thanks for the figures but they do not have any characteristics i.e. volts, ohms, cabbage, cubic meters of air etc. Not your fault but the error of whoever compiled that list. And as I know some of them I am not surprised.

I have written to the chap from Electrical who was the project engineer for TD5 but to date he has not replied. School holidays, left JLR or just too busy I do not know! Pity as I think he had several engine ECU's and other engine components.

Neptune19522 said:

Thanks for the figures but they do not have any characteristics i.e. volts, ohms, cabbage, cubic meters of air etc. Not your fault but the error of whoever compiled that list. And as I know some of them I am not surprised.

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I made that list myself to help others. As it's in the first sentence those figures are based on many live tests made by me and i dont understand why would you expect characteristics as long as you dont even know the difrence between 10P and 15P engines, those are the figures which you should see on nanocom's screen for each input and the unit is there, if i tell you that MAF is in kg/hr, MAP and AAP in kPa, and the temperatures all in *Celsius how would that help you more with nanocom while it will show you let's say 55 near the "air flow" reading at idle if the sensor is good and 30 if it's bad? Sorry for my sarcasm but i'm trying to help and get this kind of reply

My reply was not meant to be insulting!
Many sensors can be tested with an ohmmeter which I have. A simple test that tests a sensor on the bench away from the vehicle. Most of the test work I did on harnesses was completed on the electrical system with all components connected but not powered, at least all the time. The resistance of these sensors would indicate a fully functioning component or a failed component. Not all departments had diagnostic equipment. We did have a Test Book but it was cannibalised for other engineers to maintain their test equipment. The concept that adequate diagnostic equipment was free available is a myth. We made do with what we could make or scrounge ourselves.

Later engines need a MAF to run properly, ealry ones OK without

Neptune19522 said:

My reply was not meant to be insulting!
Many sensors can be tested with an ohmmeter which I have. A simple test that tests a sensor on the bench away from the vehicle. Most of the test work I did on harnesses was completed on the electrical system with all components connected but not powered, at least all the time. The resistance of these sensors would indicate a fully functioning component or a failed component. Not all departments had diagnostic equipment. We did have a Test Book but it was cannibalised for other engineers to maintain their test equipment. The concept that adequate diagnostic equipment was free available is a myth. We made do with what we could make or scrounge ourselves.

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There's summat on the front of the 15p engine where the EGR piping goes, that isn't there on the 10p engine. Can't remember what as I have a 10p, cooler maybe.
And I'd try hard to not upset @sierrafery as he is a huge guru in all this. (I know you didn't mean to!)

Thanks for your help Stanley steamer. Harness problems or even making a loom from scratch I am well capable but engine were the area of the other chap in our workshop sorted out. I will listen to anyone who knows more than me but I do have 42 years at JLR and did pick up a lot but not just engine's!

Neptune19522 said:

Many sensors can be tested with an ohmmeter which I have. A simple test that tests a sensor on the bench away from the vehicle.

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Many sensors but not the really important ones...there's no way to rule out important sensors like the MAF or MAP based on resistance check other than find it open or solid short circuit, the MAF's resistance is temperature dependant and it's an electronic circuit's resistance not a simple resistor so the value will vary based on the ambient temperature and the multimeter's battery voltage too... the MAP sensor is a pressure sensitive piezo crystal, ohmeter is useless again....the only sensors you can check on a Td5 with partial accuracy based on ohmeter are the NTC sensors like the ECT/FT or IAT which have a chart like in the attachment or the ABS sensors which have a winding and declared resistance range, eventualy the TPS which is kind'a potentiometer. Better learn to use your nanocom once you paid good money for it cos that's the proper way to diagnose management problems and the inputs are the best signs of theyr's behaviour, believe me or not.

You are perfectly correct in that the MAF cannot be fully tested with a DVM however as long as there is a circuit then the chances are that the MAF is still functioning but the efficiency of that component cannot be fully tested without advanced instrumentation. A short circuit would automatically condemn that component. To expect accurate resistant readings from a DVM particularly one that is well out of calibration would not be logical, they must be considered only indicative. Which is what I have done! Whilst I acknowledge your depth of experience and knowledge of the Discovery 2 I hesitate to rush out and spend £80 on a new MAF before I exhaust all other possibilities with my limited knowledge and equipment. Ideally I would like to try a known good one and then take it from there. New fresh out of the packet does not mean good fully working although it is highly probable that it is; I have fitted too many 'new' faulty components to ignore that possibility.

It's more simple to test the MAF or any other sensor by connecting nanocom on inputs fuelling or instrument mode and watch the figures, if you get readings like in my list the sensors are OK. Of course that if you want nanocom to work for that you have to plug it in then start the engine or plug it in while the engine is running.

You mean it does not plug itself in?

All worth trying but not now it is 20:16hr here and tomorrow is a new day.

Todays, Tuesday the 10th of May, report
Checked out the MAF connector and firmly reconnected it. Started up and there was that delay with the rev's jerking up slowly until throttle authority was there. Reading on the Nanocom was stepping up for the air flow - forgot the precise numbers but it was increasing well above the datum seen when disconnected. Disconnected the MAF and 4.4 was stationary on the Nanocom. Less of a stepping problem and throttle authority was quicker. I have to say that I am not totally convinced that this is the MAF. It would be one huge coincidence if the MAF and the engine ECU fell over at the same time, although I do concede that once under way the MAF may have fallen over between my stop on the service station and arriving at the club.

Inspection of the 'Mini-Timer' connection showed that the pins were tired and I will try to squees them gently to establish a good connection. I suspect that there has been concern over the MAF from the previous owner. The absence of the anti-back out on the xyz switch is also an indication of some meddling - the xyz was poorly adjusted when I picked the vehicle up!

Update number 6
Replaced the MAF with what is supposed to be an original equipment component. Checked the settings with Nanocom and they were very much the same only about 5% better than the 'old' MAF. Reved the engine, off load, to around 3K rev and figures went up to 300+ area.

On start up the MIL light was flashing and while the engine is still subject to the 120second delay before there is any throttle authority. Once the throttle was working the MIL light was extinguished.

I looked for any faults with the Engine ECU and the BCM - there were no faults logged on either unit!

Whilst waiting for the MAF I did an oil change but I do not think that had any affect upon this problem.

Anyone got any further ideas?

Neptune19522 said:

On start up the MIL light was flashing and while the engine is still subject to the 120second delay before there is any throttle authority. Once the throttle was working the MIL light was extinguished.

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The MIL is suppozed to flash in ONLY one situation: if you push the throttle 5 times for the purge process untill it's done(around 2-3 minutes)... this is definitely an ECU misbehaviour cos it seems that it goes into purge mode without request ... check the accel way 1 and 2 inputs after start up without touching the throttle and if they are OK and steady the ECU becomes very suspect

OK tested that.
Acc Way 1 - 0.567 off - Not measured with engine off load
Acc Way 2 - 4.465 off - Not measured with engine off load
Acc Way 3 - 4.677 off - Observed to be not very closely following way 2. Minor moment at around 3k rev 4.677 changed to 4.676

Starting was very quick moving from the no acc peddle to throttle authority, about 10 seconds. This was normal behaviour under the old engine ECU. Could cycling the ignition have caused the new component to 'settle in', (for want of a better phrase). It was my assumption that the engine was moving from a starting condition to a running condition but you have stated that there is no such condition! Perhaps I have always had that 10 sec delay? This sounds like it could be the throttle pot' miss behaving. I have a spare Disco 1 'pot' and another that may be a Disco 2. Is this throttle pot mounted inside or adjacent to the peddle or on the engine?