Rcutler - thanks - Interesting - seems similar - it is driving me mad but not very fast !!! The problem is noticeable at most times of the year but is really bad now in the heat. Have changed and checked some of the sensors but could it be the inlet air temp sensor in the Air filter box. Some have said it doesn't affect much but presumably it serves an important temperature purpose ? Or could I have problems with injectors and what they are told to give the engine ? But as I say - same problem for petrol and LPG. Don't think it is coils because out of gear engine revs smoothly to full speed.

Unfortunately, until i have time and a second vehicle I will not be investigating the fault as it doesn't really cause me too much of an issue. (I know how to get around it when it happens) plus its not usually that hot here and I only tow maybe twice a month.

I don't think it will be a temperature sensor as the actual engine temperature never really rises, its the ambient air temp and the fact the engine has been working harder in the heat.

I understand - another thought - does anyone understand the full implications of 'cruise control'. Mine is broken and I found it very hard to replace because the place where the pedal switch plugs in is too close to some other part. But I replaced the rotted rubber hose that comes up into the engine compartment and this quickly rotted again (sub standard hose here in Spain) and has been hanging around not providing any vacuum. Does it affect the running of the engine if this hose is open to the outside ? That is something I hope Gilbert picks up on !!

No, the cruise control uses it's own little dedicated vacuum pump rather than engine vacuum so doesn't affect the engine running at all. The intake air temperature sensor only does anything if temperature gets very hot, over 55 degrees, so that could be achieved where you are and that causes the ignition timing to be retarded. Retarded timing would cause a reduction of power if the sensor is thinking it has got that hot. It's a fairly standard resistive sensor, high resistance when cold, low when hot, so substituting it for a 1k resistor might show a difference if that is the problem. I know that the ECU can detect an open circuit and log a fault code (having started a car having forgotten to reconnect it). If it was shorted wiring (signifying very hot all the time), then I would expect it to be the same whether hot or cold.

Thanks Gilbert - just can't believe you know all these bits of detailed info on P38's ! What would we do without you. I did put a meter across the inlet air temp sensor points and lead - both ways and got a continuity reading - engine not running. Went out to collect some spares brought out by friend from UK - hot again and under load up hills engine just goes slower and slower. I change down to lowest gears and jump on throttle - gets by but seriously wrong - will play with the air temp sensor - don't have a spare - what happens if I just disconnect or plug on the spare Engine coolant sensor as a test ?

If you disconnect it, the open circuit will make it think that it is extremely cold but will also flag an error which may well make the car go into a fail safe mode so could affect the running anyway. That's why I said to put a 1k resistor in it's place as that will make it think there is something there. Putting another spare temperature sensor should work too, they are all pretty standard NTC sensors. Just a shame your RSW software doesn't show live readings, if it did you'd be able to see if the mixture is going rich or lean or if the ignition timing is altering when it starts to go all gutless. That would give us a clue as to what is happening.

How do I remember it all? I sometimes don't but know where to look to remind myself. It's one of those things that they say is down to how your brain is wired, I've got an analytical mind, I can work through a problem almost like a flow chart, if this is happening then it could be this or this but if it was that, this would also happen but it isn't and so on. You'd be amazed at the number of faults I've managed to work out in my head while driving along a motorway with nothing better to think about. Using my car to drive long distances around Europe means it's better to have read up on how something works first so when it doesn't you're halfway to solving the problem.

That makes sense Gilbert (actually I think its Richard) - and I will persevere and only try to swap with another sensor. So does Nanocom read all the live readings ? Maybe if I could have found one for about £350 like Chris did I should have gone for that. Have lost all my big UK customers here so living like the church mouse and would you believe that the rats who visit my P38 don't even bother with the cheddar cheese I put in the trap. By the way, just watched a TV documentary about the Germans in Russia and when the big offensive was to start in the winter they found their tanks failed because mice had eaten the wiring - I know the feeling here !

You can see alot of the functions of the Nanocom off the emulator - https://www.nanocom-diagnostics.com/downloads click emulator from the top bar.

The current price is €474.81 or £446.42 - so given the current exchange rate you'd be getting a better price in Euros anyway. Still a lot of money to find at any rate unfortunately. Even second hand they aren't cheap, as they do the job well unlike some of the tools out there.

I've seen the results of rats finding some house wiring - all the insulation stripped off from around 10 feet of twin and earth cable in a ceiling, amazingly they survived doing so as well, despite it being live as it was the lighting and sockets ring main.

Yes it is Richard, Richard Gilbert but known at work as Dick with an IT login of Gilbertd, so I use it in loads of places. For the first 5 years of ownership of my P38, I didn't have a Nanocom. For the EAS I used the earlier, free Version 2 of EASUnlock with a £20 cable from eBay and a generic code reader for engine codes. Those two allowed me to do most things but I couldn't read the ABS, HEVAC, BeCM settings or SRS and I couldn't reset the adaptives. I finally bought the Nanocom when the price was right (as the manufacturer is a Brit based in Cyprus they are priced in Euros so I just bought when the exchange rate was at it's best) to give me the ability to read the HEVAC and be able to reset the adaptive values.

You can do all of those with the RSW software, the only thing you can't do is see the live data from the engine. I have one of these https://www.ebay.co.uk/itm/Launch-Creader-VI-6-OBD2-Engine-ECU-Fault-Code-Reader-Erase-Diagnostic-Tool/322349730545 which not only gives live data as a number but will also show you a pretty graph too. That one is from China but there is also this one currently on eBay https://www.ebay.co.uk/itm/Launch-Creader-Vi-Box-Opened-Car-Obd-Scanner-Tool-Obd2/163061259369 in UK, new but the box has been opened, big deal...... The other thing is it will work on any car not just the P38. It works on many cars from 1996 onwards (when OBD became mandatory in the US so anything that would have been exported or built there) and all petrol engined cars from 2000 and diesels from 2003 (when it became mandatory in the EU). It even supports JOBD, a weird version of onboard diagnostics used on Japanese cars (so anything imported directly from Japan) and I've used mine on numerous different cars once my neighbours realised I could tell them what was wrong with their cars without them having to take it to the dealers. With one of them and a RSW software, you should be able to do most of what a Nanocom can do. Not as easily but cheaper.

Hi Richard, have ordered the 'unboxed' Creader - can't be bad at that price £29 - just takes ages to get it reposted out to Spain as they don't post out of UK.