Disco 2 Driver Demand tolerances

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tilly2

Well-Known Member
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1,125
Location
Stafford
On my quest to perfect my 2003 TD5, Ive checked my driver demand values, with a Nanocom, on a trip out. I had previously had a "Driver Demand" fault, which cut off the throttle whilst driving along. Ignition on/off reset the BCU. I dont know how to do a live recording of the engine parameters, so if anyone could let me know, I can do a file on it.

There are 4 values shown for the TPS, and two tracks (2 and 3 ?,) I believe should be of similar value, with one showing as an "opposite" value (1 ?,) and one a fixed voltage for supply to the TPS (4.)

This thing I noticed is that the two tracks, which should be similar can be upto 0.8v difference. Foot off values are the same, foot flat to the floor are also similar. Im guessing the tracks of the resistor pot are worn.

I did read a thread somewhere giving some info around the differences in values of the tracks, and how much it needs to be out, before the BCU throws up fault codes. I think Sierafery posted it up, but I cant find the actual post. I also see some have reported there may be an issue with either the connectors, or the loom to the TPS as well. Where is it likely to have been abraded, and would just a clean of the contacts, and checking the insulation suffice. Rewiring the loom seems a little extreme, even for me as a sparky.

Question is, is a new TPS sensor required. ?
 
Screenshots...
TPS1.jpg
TPS2.jpg
 
There is a certain tolerance which is due to the algorythm of the ADC in the ECM and resistance changes in the TPS tracks inputs which are affected by temperature or a physical wear, in a ideal situation T1 + T2 should be = supply that's the most important, T3 is a calcuated value within the ECM and it moves around T2 not similar. See the TPS description in the engine management section of the WSM
TP tracks.jpg
 
Thanks for that SF. ;)
So, track three does not need to be same voltage as track two. Makes sense now. I'll now take a look at the connections, and wiring loom for defects.Also the graph explains why I dont get any movement on track three at the top of the TPS travel.

No AAT faults since replacing it with a genuine LR sensor, so thats an improvement. Boost sorted now.. Just need to look at the poor performance and pick up under 2k revs.
 
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