Lots of possibles with this one.

The coil could have been melted if the Leo's rpm wire (which will connect to a coil) shorted to earth at some point, may be worth checking this wasn't the case, could have accidentally fixed such fault changing the coil pack.

Can't remember what fuses run what on a P38 but shorting a coil pack to earth could potentially blow a fuse that runs some aspect of the petrol system, probably unlikely because would expect a relevant fuse to run the ignition (so wouldn't run on LPG either).

Emulators as Gilbert said.

Only other things that spring immediately to mind for this are forgetting to plug in the MAF (or ducting) / If an emulator isn't used (and yellow wires are used to disconnect petrol injectors) an issue in the Leo might have first caused the coil to burn, might now be causing Leo's relay (that joins / breaks yellow wire connection) to be unable to join yellow wires.

There are all sorts of ways of disconnecting petrol injectors if emulators are not used, yellow wires can be used directly or control a relay / a relay could be controlled by the blue wire.

Check positive feed to petrol injectors, check negative pulse at petrol injectors.
On either Gems or Bosch the fuel pump relay is switched by the petrol ECU which provides the relay coil's earth. I've known the petrol ECU to work perfectly except not provide the negative to the relay so the fuel pump never runs so obviously means it won't run on petrol (but will on LPG)... You've already ruled this out, I mention it because I was once called out to fix a P38 that would run on LPG but not petrol which (if memory serves) they said had recently had a failed coilpack. Wonder if a shorted coilpack could cause the ECU to fail in the way that sees it no longer provide the fuel pump relay coil earth. Discussed this with Gilbert before, he said he's known a P38 ECU to fail in the same way too but I don't know if that was after a failed coilpack.

Question in the topic name. I don't think I've untracked any threads I've been on yet.

So far this year I've converted about 10 vehicles from Scotland and another 10 from as far South as Devon, London, one from Southampton (out of a total of about 60 I've converted so far this year). The Jag I've just done is from Scarborough (100 miles) and the Elgrand that's just been dropped off for conversion is from Leicester. Got another coming in to convert on Wednesday from relatively nearby Chesterfield. One I'm converting next week is from Aberdeen.

I like your term 'concentric' far better than the 'inny outy' term I've been using hehe.

Both pipes have to be blanked off and there can't be any flow between them. At one point I tried something similar to what you've suggested, I cut the outer pipe back to get access to a length of the inner pipe long enough that heat from trying to braze the outer pipe wouldn't re-melt the braze on the inner pipe or vice/versa. The braze has a lot of surface tension but still wants to roll away into the pipe or spill out the end. Tried various takes on this such as partially crimping both pipes just below where the braze needs to take / tried to braze a large self tapper into the inner pipe. Dare say a grub screw would prevent braze running into the inner pipe but would still leave the problem of the outer pipe. Could try a cap with a hole drilled same diameter as the centre pipe to braze on but the problem with this is that the centre pipe is attached to the outer pipe at 3 points that run the entire length of the pipes and cleaning the inner pipe up to make round to make for a neat hole in the cap would be very difficult.

I'm wishing i went with something like JB Weld / quick metal / etc when the issue was just a pinprick in a simple narrow length of pipe (after the concentric splits into 2 pipes).

Might have been having another crack at it now if it wasn't for having to finish this Jag conversion off today. If I'm very lucky the guru fella will come back to me soon and say he can get the short section of pipe I need from Nissan in just a few days... But realistically it'll probably be £400 and 2 months just in time for autumn lol.

It's not just a straightforward blank, the end of the inner pipe is set back inside the outer pipe... so any blank has to have a centre bit which protrudes to the inner pipe for inner pipe's O ring to seal to. There's a bit more to it than that too because the inner pipe is attached to the outer pipe with 3 ribs that run the full length of the pipe. It would probably by easier to fix the pipes than make a blank, I imagine the engineering firm is casting them and then drilling the protrusion. If I made just a straightforward blank that didn't seal the inner pipe the front aircon wouldn't work anyway because the refrigerant would just circulate around the rear aircon pipe... But I might try!

Had a long chat with the Elgrand guru yesterday, we both took time out from sweating over vehicles (me converting a Jag XJ8, him changing a rear wheel bearing on some pocket rocket which he hadn't anticipated would have to involve removing the whole rear leg due to it having suped-up oversized special disks meaning the re-positioned caliper bolts, which were now Torx bolts, were obscured by the bottom arm. Couldn't take the caliper slides off until he'd dismantled rear suspension lol... hope he quoted for that one!). Anyway... My car already has Nissan replacement (I found out from him Nissan make this replacement so it's OEM) sectioned front to rear AC pipe that has a joint over the rear axle (the original front to rear AC pipe would have been one piece without the joint over the rear axle so to swap like for like the rear suspension would have to be dropped). He has favourable terms with his local Nissan dealer and is going to try to get me just the section of AC pipe I need (rear section) through them. I could probably try a Nissan dealer myself but the car's a Jap import and I expect his chances will be much better than mine. The engineering firm hasn't got around to making the blanks he ordered yet, they have big batches of other stuff to make first. Maybe at this rate I'll be sweaty all summer and finally get AC working in time to help with demisting. Thought just occurred to me that I'm going to Cornwall for a week in a couple of weeks and there's little chance of bits arriving from Japan before then so maybe I'll have another go or two at sealing the pipe or resort to dropping the rear suspension if I get time.

There's a guy on Elgrandforum, bit of a guru on Elgrands, sells parts for them and has advised me when I've changed suspension etc. He was intending on having an engineering firm make up the blanking plugs you mentioned, thanks for reminding me.

I once tried aluminium welding an internal heater pipe from a Vauxhall Senator, noticed the problem when squirting hot water scolded my leg! Didn't work very well and I ended up getting another pipe from a scrappies. A difficult skill to master but when I worked at Chamber of Commerce there was a learner there doing his NVQ at a welding firm who had a natural talent for it, might help to have him around now!

How's this going?

Some people think the switch sets sat nav up to direct them to Stonehenge ;-)

How's idle speed now Hugh?

Last set of crowfoots I bought came with 2 of the same size so I got a set with one size missing. But when I've needed a crowfoot for lambdas in the past I've cut a spanner up and welded an old socket to the ring end. If you know the lambda is duff you could even cut it down and use a socket on it but I went with the ring end of a spanner so I could re-use the tool I'd made on easier to remove lambdas without cutting the lambda down or cutting it's plug off, just cut a slit in the ring end for the wires to slot through. Not something a SnapOn tool snob would probably do, which is one of the reasons I don't buy overly expensive tools that in practice aren't much better than some far cheaper but decent brands. If I lose a tool worth a couple of quid on an inaccessible part of a drip tray where it won't cause any damage if it shifts, fak it, don't want it to be worth my time retrieving it.

Hehe,.... No! I've had multiple attempts, spent loads on brazing rods, gradually cut the inny/outy pipe back when attempts have failed. Given up on trying to repair the pipe having made things worse and having to cut the pipe back, been trying to simply seal it on the last couple of attempts which would at least allow front AC to work. Bought some more brazing rods today but only because I was passing Machine Mart, while I was in there I was tempted to buy aluminium mig welding wire instead of brazing rods for my next attempt but still went with brazing rods because I can't see 0.8mm welding wire being easy to weld aluminium pipe that's only around the same wall thickness. I think the eventual cure will be to either fit a second hand pipe (which I can buy for £100 but means dropping the back axle to fit) or to get a hydraulics firm to make flexible pipes. The latter may have to involve cutting good existing AC pipes in the engine bay to connect to hydraulic pipes to using some type of yet to be researched compression fittings or fittings along the lines of those Bri suggested because the inny/outy pipe runs just about all the way to the engine bay. But if the latter worked I could fix lots of other same model vehicles with the problem and would be an easier more definite fix than the former.

Yeh, autumn will see the result!

Bah, windup didn't work lol.
I was 'detailing' my own car yesterday... fitted new uprated springs on the rear and airbags that fit in the middle of each spring to blow up with a tyre compressor in case the springs aren't enough. I used to regularly Tcut my cars but can seldom be arsed with even washing them these days, £7 for some East Europeans near me for a half decent jet wash and a free air freshener. Unusually not at a disused service station but at what would be an ideal place for me to shift to if I ever chose to get premises, far better than on an industrial estate. They've been on the A638 this side of Doncaster years but even when I'm just passing I look to see if they show any signs of packing it in.

So how does the dryer remove water? Can think of a few ways they might work but never cut one open. Can they get saturated and restrict flow of refrigerant?

Are the flexible hoses on AC systems designed to be permeable or is it just the nature? First car I had with AC was a mk2 Granada way back when I was 19, an AC guy told me flexible pipes were designed not only to be permeable (which he said is why you lose some AC gas over time) but also to leak if system pressure gets too high to prevent the system going bang. He also refused to recharge the AC system unless I paid him big money to fit a new dryer at the same time, I went somewhere else where they didn't insist I had a new dryer fitted had it re-gassed and it worked. I didn't believe all the first guy's points, though I suppose if there's an under bonnet fire the flexi hoses will burn through and leak. R12 system so if I knew then what I know now I'd probably have tried re-charging it with propane myself.

Apparently some old yank car AC system have a desert setting, with this setting (for use only in very dry air conditions) the AC vents could reach -8c even parked in a blisteringly hot desert.

Some Merc AC systems continue to work (on low) for 20 mins with the engine off. These models have a second battery and lots of electronics in a compartment between the back seat and boot, I think AC pipes also run to this area. I've wondered if the AC continues to work for 20 mins because the battery drives a mini compressor or because the engine compressor has already charged some type of storage setup?

Gilbertd wrote:

Lpgc wrote:

Is that a P6 in pic with the P38?

Looks more like an early Silver Shadow to me.....

Yeh I see that now, even if I didn't see it I'd take your word for it with you knowing old cars better than me.

Gilbertd wrote:

What's this detailing I hear people talking about?

It was tempting to wind you up a bit with.... Just little jobs like swapping head gaskets every now and then ;-)

StrangeRover wrote:

My Old man used to have an XJ jeep S568KNK.

Tiny little things when compared to even the Classic RR

P38 looks like a beast ;)

Is that a P6 in pic with the P38? My Uncle Dick (grandma's sister's husband) had one when I was little. Proper oldskool guy always wore a tweed suit, would sometimes give the women a lift into town for shopping but wait for them in the pub and sink a few pints, then either go out shooting (shotgun usually kept in the boot) or according to my grandma probably go to visit one of the women he was 'carrying on' with lol.

Sorry to read this, didn't know him but enjoyed his posts.
My condolences to those that knew him,

R.e. dryers, I'm no expert on AC but understand the principles except for the importance of the dryer. I believe dryers can in theory become kind of saturated (maybe for want of a better term), which I expect would effect flow, but I've never known an AC system not work due to a problematic dryer... anyone else?

I've moaned about my AC not working (not a P38) and my attempts to fix it on another thread. I may have time to give fixing it another go tomorrow after I've been to the dentist, more brazing but this time with a bit more prep and just trying to get the front AC working rather than front and rear evaps both working.

Seems wrong to be linking to an external forum again considering I've done it a few times recently but there's been a few replies on LPGforum including from Gilbert. To avoid copying and pasting more posts, here's the link.. http://www.lpgforum.co.uk/viewtopic.php?f=33&t=14362&p=111885#p111885

Morat wrote:

mine is on!
But Simon has diagnosed it so as soon as I can get the sodding lambda sensor off the down pipe I'll be sorted :)
yes, this isn't the P38...

Which is kind of a point for the position that LPG vehicles should fail the MOT if the MIL is on...

I reckon there would have to be some major advances in battery tech and upgrades to electrical infrastructure before electric vehicles could become what many people believe they well soon become. Recent advances in batteries haven't been due to new types of tech, they've been due to how the batteries are packaged. EV's previously used batteries made of pencil cells (lots of empty space between them), recently they've changed to batteries without the empty space. They hype the extra capacity as 'due to advances in tech' when really they just improved the packaging... so now with packaging improved to as good as can be any future advances will have to come from real improvements in tech/chemistry, i.e. a new type of battery invention - If we are to see such considerable improvements we may find the military don't need nuclear reactors on subs anymore and Nasa don't need to use hydrogen fuel cells. Seems a long way off to me, and even then there's the question of electricity generation... doesn't seem much point in generating electricity from burning fossil fuel to charge EV batteries. EVs are currently a small niche, while they're still a niche we won't see any of the problems they will bring if/when they become much more common (infrastructure / generation / lifespan of batteries / raw materials to build them).

Sloth wrote:

Thinking about it, we used to have buses that ran on LPG in Southampton, but they seemed to disappear not long after introduction.

Not entirely sure why... and now we have the supposedly worst-thing-on-the-road diesels, with older models having DEF and DPF kit retrofitted etc currently. I'd love to know why LPG stopped being a viable option.

I haven't researched what type of buses ran on LPG in Southampton... Were they 100% LPG or diesel with LPG split fuelling? Some large engines use the same bottom end regardless of whether the engine runs on petrol, LPG or diesel but the cylinder heads are different for petrol and LPG compared to diesel (swap an engine between petrol/diesel fuel by swapping the cylinder heads). Wondering if a new range of bus were to be introduced it could have an engine which no longer allows conversion to petrol/LPG as easily as swapping cylinder heads (with associated engine management changes) / or LPG could be fitted to clean up emissions of a bus with an older type diesel engine (maybe without a DPF) but those in charge thought not necessary on a newer diesel engine'd model.
Edit - Agreed with Bri, I nearly mentioned CNG/LNG might have been the case as opposed to LPG.

Posted this on LPGforum, copied and pasted here.

Just had a phone call from someone at DVSA (took his name but won't mention it here)...

He asked my advice because many owners of LPG converted vehicles have contested MOT failure (due to MIL light being on and since the stricter MOT rules were introduced) because they believe it is normal for LPG converted vehicles for the MIL light to be on. He said he/DVSA had been searching the internet for info on whether this was correct but couldn't find much info, then found my website and it seemed I would be able to answer his question(s).

I told him that the MIL light should not be on on an LPG converted vehicle.
I also told him I was probably shooting myself in the foot telling him the truth, because if DVSA believed it was normal for the MIL to be on it could be a further advantage for owners of LPG converted vehicles at MOT time!

Simon