So using the "IACV percentage" value on Nano I reset the steps to c. 23 at warm idle. Still no improvement on the warm starts though. When it fails a warm start I reach for the Nano and write the IACV value up to 30 or so, from the zero or so it read prior to start-up. No idea if I should be trusting a pre start-up value, but it reluctantly comes to life that way - I guess conversely I could write a lower fuel setting.
Starting to think of just replacing the IACV and TPS just to eliminate them, and maybe the ECT sensor. Is there anyone/ anything that can dig further into the ECM than Nano - to try and work out what fuelling schedule it's using/ why? Currently it will do short term fuel trim 39% on any start, it looks like. For a cold start that's fine, but for a warm start that doesn't work.
I'm also planning to replace the fuel filter, which clearly hasn't been done for aeons (and so may get my fuel rail pressure up), since one union is frozen solid and clearly hasn't been touched in a while. I have a good 5/8" nut to grip on, and the fuel filter nut is good at 13/16". I have been dousing with WD 40 for a few days now, no joy. I haven't been able to get a flare spanner on the 5/8 end as there is not enough clearance to get one on, unless you use a 1970s bike spanner. So I haven't been able to get a crows foot on and try and rattle it free. I've banged/ tapped the spanners with a hammer, nada...
I really want to avoid the car going up in smoke (so not heating the union), and/or having to replace the filter to pump fuel pipe. Anyone got a funky way to release a rusty union of what I guess is stainless steel vs steel

:o) the in and out bit I had, but it never hurts to point out the obvious

Thanks I never knew it tilted!! Just did mine. The tilt on mine only works in the last few mm of movement of the lever, should that help, but I'm sure you tried all the options

.... I am waiting for the next instalment with baited breath

popped onto the BBS forum - their development team were looking into this a year ago... sounds like some major editing is taking place to remove one percentage sign

Well, to be totally clear (lazy typing) Nano says "Idle air control valve (%) " with a value of 49... so it sounds like BBS got their Menu wrong (ie added the %) , which I hadn't considered, but in which case the accompanying user guide suddenly makes sense... Let me play with this and see what happens

It's not impossible that i'm lifting the wrong values as IACV steps - on Air screen no2 in Nano/ Gems I see: Secondary air status 4; curr run line position 20, long term adaptive idle 31, short term etc 27; idle speed 625, IACV 49%. I took the 31 and 27 to be my reference for Steps, but that's a bit of a guess on my part, and maybe it's one of these other values. The Nano guide could be clearer for this screen.

Thanks for your input, Richard, I will also investigate the purge valve - that whole EVAP system is a black box to me at the minute. Charcoal canister to soak up excess fuel.... Does that matrix ever need rebuilding btw?

I have a replacement ECT sensor too (black) the temperatures I reported above looked quite sensible, is it worth replacing anyway, do you thinK? This trail on landyzone has a guy who also thought his ECT was working, but replaced it and his (cold start) problem disappeared. I don't want to just change stuff for the hell of it, but it's cheap obviously

Thanks Richard
-Re IAT, i read that it is used along with the MAF to calculate air flow in kg/ hr - cold air being denser than hot air/ cold air cooling the MAF wire quicker...so the IAT wd seem to have a secondary impact in supporting the MAF ? ie it can survive on a default temp, but will mis-calculate (under-estimate ?) the mass of air flowing if it doesn't know the temperature of the air

• Both lambda sensors are closed loop at idle, they've settled down now, after being first fitted, with no issues - giving values of less than +/- 10%. At cold start/ open loop they are both showing 39%. Since the 625 idle is smooth now then idle seems less of a concern, and presumably if the ECM didn't like the 625 it would up-regulate.
• I still have the hot start issue - did it to me again just an hour ago. My IACV at warm idle is more like 40 - 50 steps ( ie 30 long plus 20 short) which was why I was thinking about backing off the air bypass via the blanking plug - but i'm not sure if the 30 step target in long plus short, or just long.
• Can the air bypass be blocked, perhaps?
• As yet my ECM still only has a zero FMFR value, presumably it needs a bit more learning.
• I cleaned the MAF with contact cleaner previously - in theory it should have worked (ie evaporates without residue), but I could redo it with some MAF cleaner if it was going to make a difference, and have another crack at cleaning the port for the IACV, but i don't suppose it needs to be spotless.
• The car's run rich (smelly idle) since i bought it, although i've done both HGs in that time, and so had the inlet manifold off and cleaned it up etc, but I can always take another look. I have replaced the air filter too.
  There was no obvious trigger to this hot start issue - I replaced the coolant with fresh a few weeks before, and the new exhaust & lambda sensors came later, partially in response to this

Replaced the IAT with LAT033 which is an NNK 10001. It makes no difference, in that the ECM "reads" -1 degrees or so when it's more like 14. Connectors are nice and shiny (at IAT and at the ECM). Botht the old and new sensors perform similarly a. in the fridge, and b. in the oven. Are the sensors actually calibratable in the ECM? Not in Nano, it seems, but are they in Testbook/ Faultmate? Is there a definitive table of what the resistance values should be at a given temperature?
Not sure if this is a red herring to my hot start issue, possibly. Idle is back on track ie smooth, but still operating about 625. Should I care that it's not +/- 700 like the bible says?

I checked my exhaust, and it's all good an tight, so If I have fumes through the vents then I guess that means heater matrix? I get nice fresh air on Lo. A few weeks back I refreshed the coolant - so if there had been any radweld holding the heater matrix together it may have been weakened

smelly, rather than smoky, and the new exhaust/ cats and o2 sensors don't seem to have helped much

Come on guys, I've got a fuelling/ mapping problem on my P38 and all you guys can talk about is climate change :o) give it a rest... help me fix-my-mix and you will have done your bit for the environment

Fuel pressure reads 26 psi at initial idle, and after removal of the vacuum line goes up to 32, and then holds, even after replacement of the vacuum hose (and still running, obv). Those psi values sound moderately low, I will change the fuel filter anyway, and see what happens, but is the low pressure something I can defer until later or can it be causing this issue?
The other thing is the idle is about 625 - whereas it should be more like 700 - I wonder if I need to adjust the air bypass to get the IACV below 30 steps - it smells rich at idle, so perhaps this would make a difference ie more air, less smell, faster idle. I pulled the IACV and cleaned it, seemed fine.
i'm also getting some kind of fumes (not necessarily fuel, but something volatile/ irritating) coming into the a/c for the last few trips, and so I'll crawl under the car tomorrow and check that the exhaust fitter tightened everything up properly.

Other thoughts/ ideas?

Shall we just draw a line under this one. I guess the pub's gone a bit off piste (mixed metaphors)

ooh - i'd missed all of this.

On the one hand i admired Greta's address to the UN, and take-down of the US politicians who tried to patronise her (see https://www.youtube.com/watch?v=icKlNgLuqzU&t=3276s at 1 hour) - on the other we should be mindful that Greta's wikipedia entry is probably carefully crafted by herself/ her people. I'm not sure I fall for the "kid converted her parents" bit. Here mum is an environmental activist, and there is a lot of scripting/ coaching going on here.
But with all these folks, whether it's her or Extinction rebellion, they will be shown to be on the right side of history, even if they irritate the hell out of the rest of us in the meantime

ok, so re temp sensors. Temp rises steadily to 72, and then the dash gauge gets to the first white line. By 85 the temp is approaching the middle of the gauge. It then continues to rise (all it idle, with a few revs) to c.95 degrees, toggling back and forth between 94 and 96. Seems pretty normal.
I keep coming back to the IAT sensor, there is a default strategy, if the ECT fails, to use the IAT (see GEMS by Poole pdf). If the ECM is ever relying on the IAT (mine's reading way too low) then I suppose it will retrieve the wrong fuelling mapping.

I'll keep hunting, but I need to find a sensibly priced ERR2946 (IAT sensor) in the meantime

Thanks George, I'll do that. Just waiting for the rains to subside here in the UK.

Ok, good spot, these Bosch ones are meant to be equivalent of ERR722: 0280-155- 884 - specs are v different from the 787 above, although I'm no injector nerd

I was just hunting for something else in Rave, and spotted that in General Specs it list the injector for GEMS as Lucas D1000 - in case you can get a better price by searching the Lucas part code...

Yep, sealed, square and lubricated. On a Defender hub there's a fairly obvious machined seat and the seal sits below the face, but iirc on an s3 they went flush.