LPG Service / fix Manchester

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TallPaul
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LPG Service / fix Manchester

#1 Post by TallPaul » Mon Mar 04, 2019 3:17 pm

Hi,

I have a 2001 Range rover (4.6 V8) that came with an LPG system on it. The LPG has been working okay, but there's a few issues with it, notably that I think the fill valve is dodgy as the flow never gets shut off when filling, it just gradually slows down until I get nervous and stop filling. Last time I did that, there was a vent of gas when I removed the fill pipe (not the usual brief blast, a prolonged 'leak' of gas from the fill nozzle). Also, if I run the car on LPG it never starts first time... turns over for a few seconds before starting. If I run it on petrol it starts first time, every time. According to the switchover lights it's correctly trying to start on petrol before switching over to LPG when it's warm, but something is preventing it starting nicely.

Are there any reliable LPG specialists in / around Manchester who could take a look at this? I don't mind travelling a bit to get to someone I can use regularly.

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Re: LPG Service / fix Manchester

#2 Post by LPGC » Mon Mar 04, 2019 3:27 pm

Not all pumps do a hard shut-off, some continue trying to pump gas into the tank when the float/fill shut off mechanism correctly tries to prevent it.. The float/fill shut off mechanisms don't totally shut off incoming gas but severely slow it, so on this kind of pump it can be normal for the fill not to quite stop but instead flow to something like a penny's worth per second. In which case you should stop filling probably before the fill speed slows to a penny a second! But the question needs to be asked - what size tank do you have and how many litres do you get in it?

I'm an installer with a good reputation for fixing systems, at the other side of the pennines to you near Pontefract.

Your starting symptoms will be LPG related. What underbonnet LPG components do you have (or name of system)?

Simon
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Re: LPG Service / fix Manchester

#3 Post by TallPaul » Mon Mar 04, 2019 3:38 pm

LPGC wrote:
Mon Mar 04, 2019 3:27 pm
Not all pumps do a hard shut-off, some continue trying to pump gas into the tank when the float/fill shut off mechanism correctly tries to prevent it.. The float/fill shut off mechanisms don't totally shut off incoming gas but severely slow it, so on this kind of pump it can be normal for the fill not to quite stop but instead flow to something like a penny's worth per second. In which case you should stop filling probably before the fill speed slows to a penny a second! But the question needs to be asked - what size tank do you have and how many litres do you get in it?

I'm an installer with a good reputation for fixing systems, at the other side of the pennines to you near Pontefract.

Your starting symptoms will be LPG related. What underbonnet LPG components do you have (or name of system)?

Simon
Hi Simon. The tank is a round one in the spare wheel well, I generally get around 70ish Litres in it when it's been run to empty (that's another problem I have, there's no warning when the LPG runs out, it just cuts out :D ).

As for components I have no idea to be honest, I'll have a look at the box when I get home. I know it has 2 vaporisers on it, which I think is unusual?

here's a picture of it I took a while ago: https://i.imgur.com/BjX0nRg.jpg

Pontefract is only an hour or so away, quite happy to do that drive if I can get it sorted.

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Re: LPG Service / fix Manchester

#4 Post by Gilbertd » Mon Mar 04, 2019 4:28 pm

A multipoint, as your picture shows you have, should automatically switch back to petrol when the tank is emptied, so something isn't right there. Although Simon says that some pumps don't shut off, I've never found one, all shut off with a healthy clunk when the tank is full. Usual size fitted to a P38 is an 85 or 90 litre tank which should take 65-70 litres to fill so you really are filling to the brim, a replacement multivalve might be a good idea too. Two vaporisers just means whoever installed it used two small ones instead of one bigger one but that can also cause problems with balance so one isn't doing all the work. However, there's nothing there that Simon won't be able to sort and it'll be interesting to hear what he has to say about it.
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'93 Range Rover 4.2 LSE, Lovato LovEco, sold
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Re: LPG Service / fix Manchester

#5 Post by Brian_H » Mon Mar 04, 2019 4:55 pm

I'd suspect someone prior to yourself has altered the multivalve (badly) to try and increase filling capacity, and the float is now hitting the top of the tank before it shuts off. You might want to try and use up as much as possible before you get to Simon - Theres a filling station a couple of miles from him anyway, but it would be easier for him to have a look with an empty tank obviously!

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Re: LPG Service / fix Manchester

#6 Post by TallPaul » Tue Mar 05, 2019 7:35 pm

Okay, pictures (apologies for the low light quality)

Front:

https://i.imgur.com/BNTvzle.jpg

Back:

https://i.imgur.com/yUEeLIv.jpg

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Re: LPG Service / fix Manchester

#7 Post by LPGC » Wed Mar 06, 2019 2:41 am

Yeh I could tell it would be Romano in the first pic.. Romano little reducers and injectors. The brand(s) of under bonnet system components won't affect the tank filling and, at this stage, won't affect advice on attempting diagnosis of the starting problem (there aren't many things to check without using software with an interface cable - easily obtainable btw). Without software just about the only things you could check that might affect the starting problem are gas leaking out of reducer vacuum connections (if gas comes out of a reducer vac connection the reducer diaphram is broken and gas leaks into the manifold when engine is off, so instead of the engine getting petrol and air when cranking it gets petrol and gas until it has pumped the gas out the exhaust and gets fresh air), leaky gas injectors (similar reason), fuel trims if you have an OBD scanner that shows live data.
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Re: LPG Service / fix Manchester

#8 Post by TallPaul » Wed Mar 06, 2019 7:45 am

So, where the LPG computer should have a connector for the interface cable, mine has a serial connector that's been obviously added at some point (it's spliced in with insulation tape). Is the wiring for these pretty standard and, if I pick up a cable off eBay will I be able to get it connected?

Actually, before even venturing down that path, is this Romano kit any good or would I be better investing in a new system rather than trying to get this one sorted?

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Re: LPG Service / fix Manchester

#9 Post by LPGC » Wed Mar 06, 2019 10:36 am

It will originally have been fitted with an 8 pin Molex type connector, likely the pins in that corroded. What type of serial connector does it have now (most likely another Molex or the more recent 4 pin Superseal type)? AEB make the electronics for Romano, AEB Molex lead pinout is the same as the most common Molex pinout but AEB Superseal pinout has data pins swapped over compared to the most common Superseal pinout. In theory at worst you'd only have the data pins swapped over which wouldn't blow anything.. unless whoever fitted the new plug went against bot AEB wiring convention and the most common wiring convention. Still would have to know type of plug and how it's wired before advising an interface cable. Worth saying that types of functionality that lend themselves to helping make diagnostics simpler may be a bit lacking with your fairly old ECU, e.g. a more modern ECU might allow running on some cylinders on petrol while the rest run on LPG and this can help identify individual dodgy LPG injectors (and petrol injectors) but this facility may be lacking with yours.

Kit is perfectly adequate for your vehicle, plenty of scope for improving the install but if parts are all in good working order there'd be little point in upgrading them as you'd see very little difference in any respect. If you found you had a broken reducer (maybe leaking gas as described above) it might be a good idea to remove both your little reducers and fit a single reducer that is more than capable of fuelling your engine at high load, a Romano HD reducer would be a good bet and tie in with the rest of the Romano theme! This would help tidy up your engine bay, no need for water pipes draping across the engine. It's not only down to the parts but also the way they're fitted, better results can be had fitting the point of gas entry closer to the petrol injectors whilst keeping pipes between gas injectors and point of gas entry short. A lot of years ago I was the first to make holes in the upper plenum to route gas pipes through from injectors mounted above the plenum to points of gas entry on the manifold , thus making for both correct point of gas entry and short pipe runs.. there's a thread on this forum about it somewhere. I suppose whether or not you should change components depends on the functional condition of your components, whether or not you should start fitting components (current or new) in a different way depends on how involved you want to get with this and how fussy you are.
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Re: LPG Service / fix Manchester

#10 Post by Brian_H » Wed Mar 06, 2019 4:12 pm

If its really a serial cable connector (a DB9 type one) it might be part of one of these ones
https://www.lpg-kits.com/Pages/interfaces.htm

My guess would say its been split off from the original plug and whoever has done it has bypassed the plug, though of course as said above it may be the case that its something cobbled together with no apparent standard at all. If you undo the tape on the wires, that would give you the start of what wire goes where if nothing else.

If your not sure, a decent photo of the connector with the tape removed so the wires can be seen (you can upload it directly on the forum btw, no need to use imgur to do it, just hit the full editor & preview button to get the extra buttons) would give someone here a good chance of confirming what your best option is.

Given the other bits you aren't happy with, I'd suggest you take it to Simon before spending any money on it as you will get a much better idea of whats going on from him having seen it, even if you want to sort the problems yourself afterwards.

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Re: LPG Service / fix Manchester

#11 Post by LPGC » Fri Apr 05, 2019 7:11 pm

I've seen this P38 today.

Fitted a new Superseal 4 pin interface connector (AEB wiring spec so to use with an AEB spec interface cable as would be the case with a newer Romano system). Seems the 9 pin serial connector that someone had fitted instead of the original Molex was one that came from a WTV interface lead. Replaced the 2 old Romano reducers with a single MJ, fitted metal water T's to replace the old plastic T's (one of which fell to bits when I undid J clips). Tidied up the piping a bit etc including ridding the engine of the water hoses that were draped all the way across it.

The long cranking before it would start issue was as suspected - due to leaking reducer diaphragms.

Noticed it had an AEB025 pressure sensor using an AEB013 to AEB025 wiring adaptor and on this age system it will have originally been fitted with an AEB013 pressure sensor. Said to the owner I bet in software the pressure sensor selected is still AEB013 and it was.. So it will have been reading incorrect pressure anyway. Working pressure was set in software as 0.9 bar but actual relative pressure was 1.7 bar. With working pressure set at 0.9 bar it wouldn't have switched back to petrol until actual relative pressure was as low as 0.45 bar... so this combined with the incorrect pressure sensor setting could be the reason it wasn't switching back to petrol when out of gas.

New reducer pressure set at 1.3 bar and software reference pressure set at 1.3 bar.. So now the pressure compensation will be much more accurate and it should switch back to petrol when pressure reaches around 0.6 bar.. *with one proviso*

The 0.6 bar switch back pressure isn't much different to the original 0.45 bar but the other changes make all the difference because with previous reference pressure set to 0.9 bar and actual pressure at 1.7 bar pressure compensation will have been maxed out during normal driving (leading to fuelling errors when actual pressure fell low enough for pressure correction to start to work properly) whereas now with reference and actual pressure more equal pressure compensation will work correctly for any pressure the system is likely to see even to the point of switching back to petrol.

*The proviso is that the ECU firmware is new enough to be fully compatible with the AEB025*. In the map screen the system still shows 'N/A' for manifold pressure , however in the readings screen manifold pressure is shown correctly and relative pressure shows correctly in both screens. Regards the not switching back to petrol for low pressure issue I did emulate the conditions under which the engine should switch back to petrol for low pressure by disconnecting the electrical connection to the front solenoid... but the engine failed to switch back to petrol for low pressure with this test... However, this might be due to the much more sudden drop in pressure that occurs when shutting off flow from the tank so suddenly than occurs when the tank is empty... In normal use it may switch back to petrol when the tank is empty as it should. It it doesn't switch back to petrol properly when the tank is empty a firmware update may be in order but that's best done as a last resort so the OP is going to see what happens when he runs the tank dry.

Injectors seemed in good working order and were left as was, just with a bit of a feed pipe change.

Been out for a test drive / re-calibration and all was well.

Didn't take any pics myself but reminded the OP that Gilbert said he wouldn't mind knowing the outcomes and perhaps seeing some pics of how it looks now. We didn't go all out to tidy the install up, idea was to get it running properly and that's been achieved.

OP says he's considering a supercharger upgrade!
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