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The Nano does that, and a whole lot more!
I don't really know how long it'll take for the systems to fully adapt as I suppose it depends how far out they were in the first place. I've always had the means to reset them, so have never had to wait.
If you're sure that the throttle valve is closing fully when your foot is off the throttle (make sure you've got the correct amount of free play in the cable- see pic) and you want to tinker with something you could give your idle air control valve a clean. They do get gunked up after a while.
enter image description here

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Right I did check the throttle closing - the strange thing is that it drops to the correct idle speed after car comes to stop and put lever in Park but then after a few seconds rises to the 1000 and up to 1500. Not sure where the idle air control valve is - I do have the manual but one has to be clever enough to know what might need checking in the first place. Found the idle air control detail in the manual but not seen on engine ! One of the short rubber pipes coming from near the throttle housing to the crankcase top looks soft and as if it is turning to glue !!

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I think I can see the idle air control valve just below and to the right of the TPS. Just around it is a 'soggy' rubber hose that looks as if it has seen better days - little surface cracks etc - i think it draws air from the valve cover top ? If I remove the valve is it obvious what needs cleaning ?

On one of my rat visits they got into the air intake and made a home in the air filter box chewing up all the paper filter for comfort. I only found out when the car came to a stop and I found the chewed up paper had been sucked into the intake and reached and blocked the wire mesh filter and the air flow ! I cleaned as best I could but it wouldn't surprise me if there are still little bits of paper floating about somewhere. This was a few years ago so don't think it is to do with the current problem.

By the way - you guys on here know so much I can't believe you ever have problems fixing your own cars ! But if you do its a bit worrying because where does that leave a relative beginner like me ?

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Your pic doesn't work!
IAC valve looks like this one without the red cover. Don't dismantle, just clean the bit in the airflow.

enter image description here

Rubber pipe turning to mush is a crankcase breather pipe, I imagine. If air leaks in there, as it's downstream of MAF, that will cause running issues.

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Tried an edit so out of sequence - but thanks makes sense now I have looked at it. Some of the pipes in the RR are shaped and preformed - like that breather - can I get a specific pipe like that anymore or does it have to bodge ?

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Cleaned IAC valve - quite a buildup of black oily stuff but not impossible - of course the breather tube just fell apart so bodging with a bit of hosepipe - haven't tried to run it yet......

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You can, part numbers as in these examples:
https://www.lrdirect.com/LLH500090-Hose-Oil/?
https://www.lrdirect.com/LLH500100-Hose-Breather-P38-Plenum/?
Or you can just find some plastic based hose and fit it with hose clips as long as it doesn't kink. Rubber water hose goes manky very quickly in oil.
EDIT didn't see your last where you used hose pipe :)
Theres a breather hose on the other side too...

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Bit late to the party here as I've been driving to get where I am (a lot closer to Super4 than normal but still a bloody long way off). I've been in exactly the same state as you are now and found that no amount of driving will get the TPS voltage to adapt down to normal. It'll appear to go part way, but all it is doing is adjusting the idle valve setting. The way it works is that the voltage from the TPS is stored in the ECU as closed throttle, when you give it a tiny bit of throttle the voltage rises and that acts like the progression jet in a carb. Idle jet supplies fuel at idle, main jet supplies fuel at open throttle and progression jet supplies it during the transition between the two. So, if the ECU sees the stored voltage, it sets the idle air valve to get the idle correct, you open the throttle a crack and the idle air valve opens to raise the revs before the airflow through the butterfly takes over and allows big gobs of air through.

So, you have two choices. Do an adaptive reset that changes the stored voltage that the ECU is expecting to see or make the voltage match the stored one. The first requires a dedicated bit of test gear which you don't have (and the unit your man has with plug in modules will be a generic tester with the modules giving the specific codes for the vehicle you are plugged into, like the £4k Snap On unit that does little more than a £30 generic tester) the second can be done with a bit of mild bodgery. Enlarge the mounting holes in the TPS so it can be turned, start the engine and let it idle at 1,000 rpm or whatever it has decided it is going to idle at, then turn the TPS clockwise a touch. That will bring the voltage down to what the ECU is expecting to see and the idle will drop to normal. Mine was like that for 3 years until I bought the Nanocom, reset it so it wasn't lopsided and poked the Reset Adaptive Values button......

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Started - idled nioely at 700 - started a short drive slowly but when I slowed down it stalled and does not like idling. All I have done was clean the IAC valve carefully and replace the breather pipe which was probably leaking since it fell open as soon as I touched it. Does this mean that the adaptive thing had more or less got it running ok when TPS had been swapped and allowing for leak on breather and now that I've put things back as they should be it has to re-adapt ??

Worse than that, returning and trying not to stall, caught the roof rack on the sun shade and pulled over one of the brick gateposts which was holding up the shade for the car !! Luckily it missed the car. Beginning to feel that luck is not on my side anymore ..........

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i think 700rpm is a bit low for idle.

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blueplasticsoulman wrote:

i think 700rpm is a bit low for idle.


700 +/- 20 GEMS
660 Thor

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really?

mine idles at about 760. when i was adjusting the lpg it didn't want to go any lower or it would begin coughing and stall.

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I can see that Gilbert knows the nitty gritty of the little man in the ECU and I can at cost drive to the RR place in Malaga where peresumably they still have suitable testbook for my old P38 but there is one thing I don't understand. Idle and most performance was fine until I put the new TPS on and I noticed when fitting that the engagement allowed the start to be at zero/beginning of travel whereas the one I took off because of the plastic keyway set a slight start on the pot. This you remember worked ok as far as idle was concerned. As soon as i tried the new one it jumped to an idle of 2500 and I took it off straightaway and replaced the original. When starting this too idled fast abt 2000 so I assumed that the 'adaptive ' feature spoken of had been at work. Surely, if the idle is set to the zero volt/impedance position regardless it would have remembered with the old one and remained as before. A bit of a puzzle.

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super4 wrote:

Surely, if the idle is set to the zero volt/impedance position regardless it would have remembered with the old one and remained as before.

Idle voltage is usually around the 0.6-0.8V mark and it is set so that idle isn't fully at the end of the travel. What happens with an old one is the plastic wears so the pot can return towards the end stop. Then the throttle closed voltage is lower than the stored voltage and you get a slight hesitation as you open the throttle (easy check is see if you can hold the revs at 900 rpm, with wear you'll find you can't, it'll be idle or 1,000+). Fitting the new one without the wear and the voltage is higher hence the high idle.

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PLEASE NOTE - Now found a pic that looks right after posting this- I haven't got as far as the CPS yet with all my problems with TPS and the Gatepost !! But looking through the manual the 'up to 99MY' CPS I ordered from Island although specified as for my 98 4.0 petrol P38 does not look like what i can see in the manual - allowing for the fact that the pic in the manual is pretty bad.

Can anyone confirm that this will be right for my RR whenever I get round to putting it on ? My chassis no. is within the range.enter image description here

Crankshaft Position Sensor V8 DISCO1 DEF RR P38 (Lucas) ERR6119
Crankshaft Position Sensor V8 DISCO1 DEF RR P38 (Lucas) ERR6119
Crank shaft position sensor which fits the following vehicles
Defender 4.0
Discovery 1 Auto from engine number 50D 09964A
Range rover P38 from Chassis number VA346794 TO WA410481

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Having said all that and wasted your time I have found a diagram in the manual (very small) that looks right - confusing because it shows the lead attached. Just feel feted to have problems with this job !

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As long as your VIN is in the range VA346794 to WA410481 then ERR6119 is the correct part
enter image description here

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Anyway, just to show you what sort of prat you are dealing with - here are the pics of my fallen gatepost - amazing what a P38 can pull.............![enter image description here](https://i.imgur.com/EV09Fwk.jpg "enter image title here")

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Any bricklayers among you ?enter image description here

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T plate? 98? A 98 would be on an R or S plate, a T would normally be a Thor not GEMS and would have a VIN starting XA. Or are you trying to confuse the Spanish by running false plates?

However, as long as you have the correct crank position sensor, it will just work. If it will bolt in and the cable connect to it, it is the correct one and a dead CKP will stop the car from starting. So if you fit the new one and it starts, it's fine.