Nanocom Reading

Hi,

A few questions regarding the readings and hope someone can help...

My accelerator pedal way 3 reading can get up to 8v so does that mean that it's had it?

is it normal that the manifold pressure not reaching 200kpa when driving at around 2000ft with an ambient pressure of around 89kpa?

Further more cylinder 1 & 3 reading can vary from -8 to 8... can they be serviced or do I have to replace them?

It's a 2000 Disco 2...

Thanks

Hi Borneo,

1. Don't know

2. Normal inlet manifold pressure at sea level is about 220Kpa. This is made up of standard atmospheric pressure of 14.7psi (101.3Kpa) and the maximum TD5 turbo boost of about 17psi (117.2Kpa) making up 218.5Kpa

At 2000ft your ambient pressure reading of 89Kpa (12.9 psi) is about right so with maximum boost of 117.2 Kpa you're going to be reading about 206.2Kpa. Of course your maximum boost is going to compress less air at 2000ft than it would at sea level so is you maxi,um boost is down by 11/12% then you are going to get a reading of about 192Kpa max. at the inlet manifold. My maths are done in my head so they're spot on but near enough to be accurate.

If you are at that altitude all the time I would suggest upping the boost on the turbo so it pushes out 11 or 12% more boost about 19psi (131Kpa). This would bring you back up to 220 Kpa at the inlet. Again if you go down to sea level and floor it may sense overboost and cut back on power as it is supposed to do.

3. Cylinder balance readings are only of use when idling or pulling at a constant power, not accelerating up a hill but pulling at the same speed for instance. As soon as you accelerate or lift your foot off slightly the balance readings are meaninglesss. I read somewhere on the web that TD5's give an error reading in the ECU if cylinder balance is above +15 or -15 when it shouldn't be. If you look at your fuelling records with Nanocom you my find the odd reading which is above these parameters for instance after hard acceleration and lifting your foot off quickly but the engine's clever and won't log that as a fault whereas it would if it were idling.

Hope this helps

Hi again,

Just been looking at some of my old fuelling records for my 2000 TD5 Discovery. I think I can answer you question 1 now. My model only has a 2 pot throttle sensor and not the 3 pot one fitted to later models but Nanocom comes up with a pot 3 reading. At constant speed, say on a motorway it reads 0 but as the readings fluctuate I have found voltages on pot 3 up to 8.6v. The readings from pots 1 and 2 never go out of range. If you have a 2 pot model up to VIN297136 then don't worry about pot 3 readings.

Regards

Hi,

Thanks for the feed back...

Now at least I can eliminate pedal and injectors as the problem...

Might have been worth mentioning the problem - who knows, more info might have helped set the alarm bells off for someone...

HAha!! you have a point there...

Basically horrible pick up especially from rest and moody gear change...

Sometimes it'll change ok but sometimes I need 3000+ before it'll change up under lite load... changing down in a hurry is extremely rough with a loud clunk...

Basically the car was in the workshop for over a year...

You can read about the history in "No Power!!!!!!"

As far as I know the Disco TD5 (as opposed to the Defender) compensates for lower ambient pressure by means of the ECU controlled wastegate modulator.

At 1200 m (just shy of 4000 ft) I get AAP (ambient air pressure) readings of 82-86 kPa (Nanocom) and still have inlet manifold pressures of up to 220 kPa -- in fact not far ago when a wastegate controller hose broke up the modulator stopped working and MAP (manifold absolute pressure) went up to 230 kPa, point at which the ECU went into limp mode. Since on the Disco the wastegate actuator is electronically controlled, fiddling with shaft length won't make much of a difference. The sometimes noticeable decrease in performance at high altitudes does not come from reduced turbo boost but from lower oxygen levels in the air mixture.

With regards to cylinder balance... what sort of diesel quality do you get down there? my local diesel is crap (high sulfur) which forces me to clean the injection system at regular intervals by means of an external pump. When dirty, apart from smelly & smoky exhaust gases (the later seen at dark with torchlight) and fuel inefficiency, I get cylinder balance readings of up to 5 or 6 (+ or -) but after 'doing' the injectors they usually come down to 2 or 3 (+ or -). Despite this, I have noticed that different engines tend to give unlike cylinder balance 'baselines', so I would not only look at balance readings from a quantitative stand point, but rather at uniformity... i.e. if a specific cylinder has consistently higher readings than the rest then that could indicate potential trouble within it (and not necessarily injector type trouble). As already stated, cylinder balance readings are preferably to be taken with engine at idle & operating temperature.


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Matt

hi,

Thanks for the feedback...

Will get the injectors cleaned and see if there's any improvement...

Did notice that the engine is very slow to built up rev when stopped on a steep slope... it will eventually get to 1500rpm then stop there for a while before getting more rev and moving the car... any idea?