LPG Discussion Forum

I put a few Qs to Dai, and I've had a quick email from him:
Rightly and correctly, he's shot down my idea for running the Necam in semi-emulation. This won't happen because as soon as we fire-up the Necam, the petrol-injectors will have their input stamped-on at the Necam end. Hence, it will never fly will it? Not sure why I had not come to that conclusion rather sooner, but then I'm playing at this.

Thus a TAP it is. Not the first clue, Dai will have to put me straight on which one. Thing is, as discussed, no b*st**d's got stock of anything anyway. I've got plenty to be getting one with, but at the moment, I'm waiting on a hydraulics-delivery for some of the more exotic fittings.

Pics of the Volvo XC70 T5 I converted recently.

Finished engine bay





I initially noticed unusual (none standard Volvo) hose clips on the thermostat housing to plenum heater pipe and radiator bleed to expansion tank pipe. There was also a bit of rag tucked down the side of the expansion tank. Then it started overheating when I took it on the road to calibrate the LPG system. I suspect someone had already noted problems with the cooling system (the none standard clips and rag next to the expansion tank), the water pump failed while I was driving it (and giving it some stick!). I was fully booked and too busy to change the water pump myself so I farmed the job out to a local mechanic I trust, he left the old parts he removed in boxes in the passenger footwell. This was the state of the waterpump, which definitely (lol) shows why it was overheating..



The mechanic reckons that while he was at the job when he removed the fanbelt the PAS pump suddenly felt slack and wobbly, when it should be expected that the PAS pump would still be fully supported. And reckons that the reason for that was that he found the long bracket which holds the PAS and AC pump in place was snapped, the only reason the PAS pump felt rigid with the snapped bracket was due to the tension from the fan belt.. Pic below of the snapped bracket. A local aluminium welder fixed the bracket for £50. But the mechanic added £60 for removing, refitting and delivering/collecting the bracket from the welder.



Anyway, all sorted now, runs great. The owner is even pleased that he had the water pump, cambelt, tensioner and idler changed and the bracket fixed for total of £360.

I very much suspected the water pump was at fault at an early time, but then spent ages making sure I'd bled the cooling system properly and removing the thermostat in case it was stuck shut. Seemed strange that the LPG reducer soon heated to engine coolant temp even though the wp was broke. But of course I asked Dai's advice in all of this because it would be crazy to have a mate who's probably number1 expert on Volvo's and not ask his advice. Dai's help and advice very much appreciated as usual, cheers Dai.

CNG wrote: Fri Apr 16, 2021 1:37 pm I put a few Qs to Dai, and I've had a quick email from him:
Rightly and correctly, he's shot down my idea for running the Necam in semi-emulation. This won't happen because as soon as we fire-up the Necam, the petrol-injectors will have their input stamped-on at the Necam end. Hence, it will never fly will it? Not sure why I had not come to that conclusion rather sooner, but then I'm playing at this.

Thus a TAP it is. Not the first clue, Dai will have to put me straight on which one. Thing is, as discussed, no b*st**d's got stock of anything anyway. I've got plenty to be getting one with, but at the moment, I'm waiting on a hydraulics-delivery for some of the more exotic fittings.

I would also assume that as soon as the Necam is fired up it will cut the connection between the petrol ECU and petrol injectors on this type of Necam system. If it were a system on a Vauxhall with a 'black box' things may be different and you might have been able to take advantage of built in timing advance if it was native to the Necam system. But it's a system on a Volvo and you can't have the Necam timing map without cutting off the output to petrol injectors, which would also cut off output of pinj to the LPG/CNG ECU.

I'm sure the Volvo owner will be happy, you've even given him a spare LPG injector as a free gift.....

I wouldn't have believed that casting would fracture, but there it is, plain to see.

I would also assume that as soon as the Necam is fired up it will cut the connection between the petrol ECU and petrol injectors on this type of Necam system.

Oh, freely admit, that was complete blinked-thinking on my part. It shouldn't have taken Dai to bring this to my attention.

Talking of spare injector capacity, I'd guess it was all Dai had to hand, he appears to have sent me a 8-pot KME kit. With three pots spare, I'm set to run this thing near twice over.

I'm assuming for first rounds of calibration OBD gets used, but why might the OBD function be left unconnected once set-up?

The usual reason is a combination of it not working as well as you'd hope, combined with it trying to correct for an unrecoverable fault and messing trims up in the process (dead lambda sensor or MAF for example). KME kits come in 3/4 cylinder or 5/6/8 generally, you could use single injectors to supply odd numbers of cylinders, but not always the ideal option. At least it gives you some spare bits just in case.

Ah, of course. If we assume it's set-up 'right' the only thing that would push any change is a faulty component. And in that instance we don't want to mess up the map. Thus use the OBD to calibrate and unhook it.

Gilbertd wrote: Sun Apr 18, 2021 10:15 am I'm sure the Volvo owner will be happy, you've even given him a spare LPG injector as a free gift.....

Nothing wrong or disadvantageous with fitting 2 x 3 cylinder rails on a 5 cylinder engine though, and can have it's advantages

The reason for the 8 cyl ECU instead of a 6 cyl ECU may be because suppliers had no 6cyl ECU's left in stock. I fitted a 6cyl ECU on this Volvo but I've fitted 8 cyl ECU's on a lot of 6cyl engine recently.
With some LPG ECU's if you convert a 5cyl engine using an 8cyl ECU you use ECU channels 1,2,3,5,6. With KME use channels 1,2,3,4,5. You could use any channels you wanted but the LPG ECU would report errors for lack of petrol injector signal unless you ticked the Hemi box and even then might report open-circuit LPG injectors unless you modify error reporting/action settings. Best to stick to using channels 12345. Which version of the 8cyl ECU have you got (standard/pro)?

Up until recent versions of firmware and software KME had a bit of a bug where even if you opted to do a complete manual calibration it would adjust the map while you're doing the manual calibration. The way around that was to upload a previous calibration file in which the flag depicting early stages of autocalibration completed is already set. Won't matter if you intend to run autocal anyway but I'm not sure if recent firmware and software ever sorted the bug, I always start by updating firmware and uploading an existing calibration file anyway (to get around bug and to use as a template with a lot of repetitive settings already set).

Thanks LPGC, Dai sent me what I see as the 8Pot OBD Nevo Pro. I've sourced form Dai precisely becuase of those kind of 'unknowns' I'd struggle with on my own.

Once I get to the front-end config etc, I'm angling for Dai to have a base config for me to kick-off with. Happy to pay Dai's margin, and there' no sense if all I do is go for the cheapest on eBay - all without a Pro's 'head-knowledge' in the box. I'll pay in the finsih and it'll be a hash.

I'm still messing around with setting the rear, 'back to stock' - tanks, factory-filler area etc. Just started to attack the stainless end of the plumbing, and it's taking me forever. I'm sure the Pro hydraulics blokes can do all this in half the time it takes me. I've done a fair bit in the past, but I still make a meal of it. Stress loops, check-valves, and a whole heap of stuff not used in LPG makes it unforgiving, and time-consuming.

You did the right thing, Dai's help was invaluable to me when I first started out that's for sure.

And his 2nd opinion was great when I was diagnosing the Volvo water pump issue on this occasion.

He may has some Nevo base maps anyway but the other day I didn't know if you or he would be calibrating your system and I sent him the calibration file from the one I did above. It would obviously need changing to suit your setup but the autocal done flag will be set in that file. You might be running autocal anyway.

Thank you for that, may as well give Dai a slice as any 'know-nothing' eBay seller, and we all win. Makes sense to me, and if I have this straight, I've kinda' found myself with two Pro's behind this job?

That'll do.
Now I'm going to explain why for the likes of me anyway, an NG install is so much about the plumbing. These P80 cars had their factory-tank sited behind the rear passenger seat, later P2 under the seat. So far what you see gets pretty simple, in copper you'd do that lot in a lazy hour, in stainless it gets worse. And I've got to replace all the now long-gone, factory pipe-runs.

You're looking at a section of stainless coming from the fill-cap entering the double-skin of the rear inner-wing via that factory-fit black-plastic vent. The cardboard is there 'cos fibre-glass composite tanks are nasty - like a day with loft-insulation. LPG lets you mince about, waving a bit of copper. You make it off one end, and poke it thru'. Copper allows such runs, in-situ, on the car. Not so fast, stainless. You've got to do those bends off the car.

Because of the double-skin around the filler, it's a Volvo remember, the complex-curve required is blind and has restrictive access and sight-lines. Doing that blind, getting stainless to 'land' dead-centre to that black-plastic vent took time. When you blind-work this as well, mocking-up with welding-rods for a template, took me three goes. If you've ever had to create complex-curves for say an exhaust system, you'll grasp what I'm on about. One bend is fine, once you're at two and three, where the pipe 'lands' becomes an art in itself. If you get the third bend wrong, the previous two become scrap. And you can't 'offer it up', after the second bend, because it won't wiggle in to fit. I'm surprised I did it in three.

OK, the stress-loop you see, was a 'piece of the proverbial'. Easy, because a check-valve has to be in there somewhere, so I chose to place it mid-loop - no reason to make a section of pipe with four curves to get wrong, when you bend-up as two, and give yourself some 'wiggle', check-valve in the middle? Thus the check-valve becomes a swivel-fitting too. But it's still time-consuming.

The frightening one is yet to come. That long run that has to land on the tank-valve at one end, and go vertical up the bulkhead, orientate at right angles, and land on the reducer at the other, is a daunting prospect. In copper you'd just flounce about the workshop, and 'Whoopsie' it in.

I've got to do that off the car. Volvo must have produced the original on a former and then all that would be required is to snake it in. Me? I weep, rather than a few fittings added each end to make off to LPG, the previous bodge ripped that beautiful piece of stainless out. And fired-in lash-up copper. It needs to be done again, and in one section of pipe for best practice. OK, I've done similar before...but I don't know if I'm that good.

We'll see.

Pix from the 1998 vintage showroom blurb. This variant gets factory fuel-gauges in the plural, which means you lose the more conventional temperature gauge seen in the liquid only Volvo P80 models.
I like my Scanguage, it's neat, tiny and sits unobtrusively on the gauge-cluster ledge, and I've use it as temperature gauge.
Running OBD to the Nevo, Dai informs me, the Scangauge might have to go. OBD likes to run one thing not two?
Via OBD on my Scangauge, I was hoping to watch the Lambda doing its thing in calibration too. Seems not.

That's a pain.

As I get deeper into the meat of this job, I think I'll wire it such that I can, unsplice the Nevo, or unhook the Scangauge as I see fit.

I think I said, I'm going to stay with the factory fuel-pressure sensor and run the gauge in the stock-cluster. Gets plumbed-in next.
For the KME Nevo to work, Dai tells me I'm not required to connect the Nevo up to any AEB type fuel-level sensor. Because of the various versions, and unlike AEB's LPG sensors the outputs vary, those AEB NG models are pricey and a headache, so I won't.


It's a whole 'other subject', and I can feel myself starting to rant... but the stock gauge for NG should be the AEB806. Or the AEB807. It seems to depend on AEB's mood how these output. Will it be... 0<5V; 90<0Ohms; 0<12V; or 5V>0. Sold by AEB as AEB806, I've had all four. Complicated by the Chinese, I'm pretty sure all AEB806 are in fact made by CNGauge in China. CNGauge model CNG201C is sold as AEB806, but differs again. Whichever one you buy, it arrives described as a AEB 'Standard gauge' with the same AEB drawing shown here.
Worse, the colours will vary, and your guess will be wrong. You'll get a 680Ohm resistor too. Never did work out why, and you won't get documentation to explain this. Thus, if you can say from that drawing if you're looking at a 0<5V; 90<0Ohms; 0<12V; or 5V>0 when the colours on your gauge differ, you're better than me.
Don't get me started on the 3K KE046 from the Turkish crowd, I've got one of these laying about too:

Now chuck in some pigeon-Italian, some Chinglish, and smatterings of Turk-lish.

Dealing in NG, I've haemorrhaged cash on gauges 'cos there's no one to ask. Ask any LPG Pro and they look at you like you're a simpleton - "You mean you can't connect 2-3 wires?"
I see the 3K gauge is now sold on eBay, I had to import mine. described as a CNG gauge from a Turkish language site. No info, no choice, no options left, I took pot-luck. Lady-luck failed me.

Bring back the AEB1050, AEB1090... all is forgiven.

My experience in use of AEB806/CNG201C on the less flexible single-point switches is a tale of woe. Those things like resistive 50Ohm, 90Ohm 4800?Ohm LPG senders and not much else. No Pro does NG. Likely won't be a problem with a software driven box like this KME jobby - I suspect the thing will take outputs, 680Ohm resistor et al, in every flavour, and for similar reasons you won't be found making the gauge fit your ECU/single-point because you can make the ECU fit to the gauge.

For those coming in behind me, you are forewarned. This ismy third NG conversion, and this aspect of it has yet to be straight-forward. Your mileage may vary.

Oh yeah, and likely as not to get the gauge to seat, and still be 'clocked' such that it's orientated to face-front, you'll want a 1/4 BSP gauge-swivel. Ignore that price, your hydraulics supplier will have these at £2-3.
This is a gauge-fitting. Not shown, there's an O-ring which sits around that nipple as a seat. Make sure you get the O-ring. Small, it's often omitted or easily lost in the deal. Thus because you'll not knwo what's not there to see, it's common for the fitting to go in, minus the O-ring. Of course 1/4 BSP gauge can be made to seal on the thread, but not best practice at these pressures.
Plumber's White PTFE tape is for water, even the yellow reel, 'gas-fiiter-grade' stuff is for domestic and low-pressure like LPG. I was told by a high-pressure flammable gas Pro 'yellow reel' is not best practice. It may gall the thread if you use too much, and not move if you use too little. Brush it on, and LA-CO moves and pressure packs it down as it dams-up in a seal. Above my pay-grade, I think the hydraulics-trade uses 'Threadlok', so different again. Threadlok sounds sensible but (maybe) it won't sit with methane / hydro-carbons? The LA-CO recommendation comes from a petro-chemical bloke working at er... 'pressures-daft' - I'd guess he has it right for this application.

Not that I'm unwilling but I don't want to volunteer too much input here because I haven't discussed getting involved with this with Dai and it's his project, I wouldn't want to say anything that could steer things away from any of his ideas which we haven't discussed.

I use the PTFE stuff on small diameter tapered threads, for wider tapered threads on e.g. 4 hole tank valves I'd still use some PTFE tape for a couple of reasons... without it the valve might screw further into the tank before it becomes tight and then the valve being screwed in might not line up as it should with the pipe holes in a gas tight housing. I trust the runny PTFE stuff more on fine threads than on coarse threads... But it is very good stuff and makes far easier work of making reliable gas tight seals on fine tapered threads than using PTFE tape.

Nevo level sender options are the usual 1050/1090/1090 reverse, reserve only, 20k... and AEB806CNG.

Thanks LPGC, but I jest. You sending Dai a file is more than enough, and I'm sure Dai knows this system.

I use the PTFE stuff on small diameter tapered threads, for wider tapered threads on e.g. 4 hole tank valves I'd still use some PTFE tape for a couple of reasons... without it the valve might screw further into the tank before it becomes tight and then the valve being screwed in might not line up as it should with the pipe holes in a gas tight housing.

Those applications sounds very reasonable to me, I'm only citing what I've been told for high-pressure stuff, I don't actually know for fact, any of it. I am aware that Swagelok get very picky about torques and distance gauges etc to all fittings for high-pressure stuff. But that crowd regard much under 1000psi as low-pressure. None this is very relevant to LPG.

Nevo level sender options are the usual 1050/1090/1090 reverse, reserve only, 20k... and AEB806CNG.

Oh dear, not as many flavours as I'd hoped. I kinda guessed. Good job I've got the factory gauge. If my experience is an indication, it's still not clear what AEB think their AEB806 puts out, and believe me, none of AEB's documentation will tell you. How the Nevo can know when I've seen several variants is anyone's guess.

I still don't know when, and where you'd find use for the 3K gauge with a 12V output. I thought most stuff was 5V, and classic cars have always had resistive gauges. The Chinese do give more info, but it's difficult to know which CNGauge variant you're getting, until it lands. There appears to be light at the end of the tunnel here, seems a fresh source on eBay has Aitiker 90Ohm CNG gauges, and actually describes them as 90Ohm. This is new, in the past I've been forced to buy blind,and they come in as 5V>0 or something clunky. The Turks are big on NG. I shall bag one of those as No.4.

I tell KME what changes would be handy in the next update to Nevo firmware and software and they usually include them. If for example I did a few CNG installs, say a couple of dozen, I might have a few suggestions regards CNG level senders etc, but I don't have experience of CNG. The piping reads to be a bugger... But I'd still expect the real skill to concern the selection, setting up and calibration of the fuel system rather than the nuts and bolts aspects, not on a Volvo but for sure on some vehicles. A hydraulics guy could fit CNG pipes but not necessarily be able to get the engine to run properly, an alternative fuel guy's specialisation is fuelling? For sure Dai can do fuelling and for sure I can do fuelling. Plenty LPG guys can do nuts and bolts and piping, the high pressure stuff reads more challenging but is still a nuts and bolts thing, there won't be many installers who know alternative fuel fuelling as well as Dai or myself, not your average installers..

Oh, have no doubt, I don't under-play what comes next. The damned fuelling, I speak of the pipe-work in this conversion because that's where much of the man hours to one of these jobs is. My last conversion took a week to do the pipework. If I say so myself, It's a work of art. More because I took the time -for my own safety - to make sure it was. I wanted it to look 'right' too. Only, I can't see how a pro could make money doing it?

In this job, returning to factory-fit, I'm sure Volvo would have had the 'long back to front run' on a former and floated it in, prior to fitting too much else to the body-shell. Done like that, I can see the pipework done in minutes. My way, offering it up, is days, uses more fittings and is a pain. It's looking like I've cracked the main run. I wouldn't say it's hard work, or particularly difficult. It's more difficult to get right, first go, each and every time - without wasting pipe.. and time.


The take-away is that for a UK install, NG parts are obscure, hard to source, pricey, and when you do get them, take forever to fit. And with the UK's focus on LPG, no one can tell you the pitfalls, thus, you fall in every one of them!


Pipeowrk near beaten, I'm feeling pretty cocksure. The humble-pie stage is next.

The pipework does read to be a pain, always expected it would take longer than LPG pipework but would expect to speed things up with growing familiarity (of components and practices)? Not to the same speed as fitting LPG piping but for sure to get the whole job lot conversion done in maybe 4 days altogether? For sure an otherwise busy with LPG conversions pro like myself would lose out in the short term due to taking too long due to being unfamiliar, but would then get quicker and charge only the extra time when up to full speed on the CNG conversions?

Instead of spending a lot of money on suck it and see pressure senders, why not buy a generic pressure sender and interface it's signal to your choice(s) of LPG ECU(s) using a cheap microcontroller system such as Arduino that has onboard AD and DA convertors, plus maybe some very basic electronics. Doing this you could probably use any pressure sender you ever bought with any LPG ECU and expect to get a more accurate gauge than an LPG system gauge.

CNG is common in many 3rd world countries, surely the piping tanks and senders are not mega-bucks where available in those countries?

The pipework does read to be a pain, always expected it would take longer than LPG pipework but would expect to speed things up with growing familiarity (of components and practices)? Not to the same speed as fitting LPG piping but for sure to get the whole job lot conversion done in maybe 4 days altogether? For sure an otherwise busy with LPG conversions pro like myself would lose out in the short term due to taking too long due to being unfamiliar, but would then get quicker and charge only the extra time when up to full speed on the CNG conversions?

Oh for sure, and I suspect you've done so many of certain vehicles, you're bored rigid to convert yet another Range Rooney? You'll do the things in your sleep. The job is going to take you longer but once you have it down... only it's a moot point. Can't see a queue forming at your door for this work.

Instead of spending a lot of money on suck it and see pressure senders, why not buy a generic pressure sender and interface it's signal to your choice(s) of LPG ECU(s) using a cheap microcontroller system such as Arduino that has onboard AD and DA convertors, plus maybe some very basic electronics. Doing this you could probably use any pressure sender you ever bought with any LPG ECU and expect to get a more accurate gauge than an LPG system gauge.

In the finish, anything can be done, and that's exactly what I did last outing. After leaving to blind-luck importing gauge No.3 I gave in. I use what was sold to me as an AEB806, running Full 5V>0V Empty. Now set to displaying to the stock resistive gauge in my daily-driver-classic. It's calibrated to within an inch of its life,such that 'empty' really is empty. Yet, oh dear christ... the pain in getting there?... Importing three-gauges, messing with them, taking them off again. And the cost. With LPG it'd be 10 minutes with £15 quids worth of AEB1050, and be done. Some imported from the states, others Europe, for a fuel-gauge my bill's over ten times that. When the whole point in this was to save money? And I twist on...

If indeed it is a 90Ohm, I'd have been very, very happy with what I now see on eBay, see piccy.

CNG is common in many 3rd world countries, surely the piping tanks and senders are not mega-bucks where available in those countries?

They're not. And its' helped by for example India and Argentina as the big markets, Maruti (Suzuki) make NG stuff straight off the showroom floor. For conversions, no doubt most of it comes off the shelf, much as LPG kits for a Range Rooney does here.

Nothing in stainless, they'll run in a dodgy out-of-date cylinder and bang the rest in. It's where the expired German and Italian cylinders wind-up. With the added advantage that this work adds to the heap of Youtube videos with some horrific accidents. You might see why I refuse to play.
This work to this standard would be pricey and time consuming anywhere. It restores the install to the same, or above, the standard of the Volvo factory-fit. I can see ways to short-cut this job, I'm rather forced to exceed the standard of the Volvo fit because my replacement Luxfer cylinder has different, and therefore far pricier fittings to the original factory Raufoss jobby. That changes pipework, and the install, and puts the time, and cost, way up. If I used that Raufoss, I could be driving around this minute, and wouldn't be doing this work. I've only recently disposed of my 5 years out-of-date, Raufoss cylinder. Use that? Nope, I think not.
It's counter-intuitive, but done right, there's a heap of evidence to suggest that LPG is safer than Petrol. People simply don't question the more familiar risks associated with petrol. Broadly speaking, petrol is very dangerous stuff - there's a heap of increasingly horrific Youtube accidents to show for it.
NG cylinders get tested in train-crashes, try that with a Stako? I can't see petrol safe in a mothers'-meet, pram-fight? For me, a proper NG install exceeds the safety of LPG. For fear of sounding a little pompous, I'm happy to take the time to be sure it is.

The other impetus for this is that, for insurance purposes, I don't want to be found wandering into the modified car arena. Keep it stock, or as the insurers describe, 'with periodic maintenance, like-for-like, parts equivalents'. Such that, it's nailed to the floor. If, god forbid, your friend and mine, our loss-adjsuter ever does knock; he won't find anything with which his client can wriggle on. My advice: keep 'em skewered. e.g: just in case they deem to judge my change of reducer etc 'a modification' - I always declare this factory-fit as a 'conversion'; when to the pedantic last letter, it never is. From experience with insurance companies, they'll try it on if they can. I'd rather appear as some smug a*se here, than stand in white-faced shock as some actuary announces 'yours truly' uninsured.

Branded Atiker, pix of the first CNG Gauge I've ever found declared as 90 Ohm. As is tradition, the Atiker web site keeps the output blind, thus how the seller warrants these as 90 Ohm, is not clear. But there it is. Cheap too.

"Get 'em whilst they're hot..."