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PostPosted: Sat Nov 02, 2013 11:15 pm 
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Hi guys, new to LPG and I need some advice. Basically my friend bought a 4.0 V8 Jaguar XJ fitted with LPG and the gearbox has gone so he's decided to break it. He says I can have the whole LPG kit for a favourable price and since my daily driver is a 1998 E55 AMG which has a 5.5L V8 I would like to fit it to that. I will be doing the conversion myself, I have no prior experience with LPG but a fair amount with cars in general.

From what I can tell, the system is a Romano N multipoint with MAP sensor, standard vaporiser and injectors.

This is the Jag:
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And this is my Merc (airbox removed):
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Here are some more photos of the system. The install is surprisingly shoddy in places considering it was done by an approved fitter, trapped wires etc. I would like to try and do a nicer job when (if) it goes in my car.
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Standard reducer
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MAP Sensor
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System control solenoid
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ECU
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Oxygen Sensor Emulator
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I've read on the Jaguar forums this Oxygen Sensor Emulator is needed to run them on LPG so is this something I can do away with completely on my Mercedes? Also I hear this type of Jaguar engine requires a Flashlube system but I can't see how or where it's fitted if there is one! :?

Apparently this Romano N system is only good for 260bhp which isn't enough to feed my engine but I notice there is a Romano HD kit which is basically the same kit with bigger vaporiser and injectors. Is it best to upgrade all this now or will the system work on my car as it is? Is running an LPG system that switches back onto petrol when pushed hard a good thing or bad thing? Some people say it shows the system isn't up to the task of fuelling the engine, whereas others say that's what it is designed to do so full power is there when you need it.

What about mapping? Obviously it has a Jaguar map at the moment! I have seen the interface kits HERE which I'm guessing I'll need, but can this system learn via OBD?

This engine is the same as mine and I notice the LPG injectors (are these Magicjet?) sit underneath the petrol injectors, so the last thing I want to do is drill holes in my inlet manifold then find out I don't need them. Also, what effect (if any) does moving the petrol injectors like this have on performance when running on petrol?

How do I remove the system safely? The gauge on the tank says it's a quarter full. I assume the tank has an automatic valve but are there any other shut-off valves, or any precautions I need to take before I start undoing pipes etc.?

Sorry for all the questions but my mind is boggling :lol: I would appreciate any advice you can give. Thanks!

Trevor


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PostPosted: Sun Nov 03, 2013 8:12 pm 
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fishmk1 wrote:
Apparently this Romano N system is only good for 260bhp which isn't enough to feed my engine but I notice there is a Romano HD kit which is basically the same kit with bigger vaporiser and injectors.

Cost it up ... secondhand tat + new pipes and hoses (you will do that, won't you?) + new reducer + new injectors >> buying a suitable new system in the first case.

LPG tank dimensions for model X is rarely the optimum fit for model Y; its another area that could be regretted later.

fishmk1 wrote:
Is running an LPG system that switches back onto petrol when pushed hard a good thing or bad thing?

It depends if you want to burn petrol or LPG. Presuming the whole object of the exercise is to burn LPG rather than petrol, fitting a pansy LPG system that can't actually achieve that seems to be a bit silly. It's no more difficult and hardly more expensive to fit adequate stuff to begin with. Correcting a poor choice later on will have a significant cost however.

fishmk1 wrote:
can this system learn via OBD?

Do not transplant a used system and expect OBD to sort it out. It will need manual setting up.

fishmk1 wrote:
Also, what effect (if any) does moving the petrol injectors like this have on performance when running on petrol?

Who knows, it all depends on the spray pattern etc. Up to you to experiment. Most folk who have used those adaptors end up not using them again.

fishmk1 wrote:
any precautions I need to take before I start undoing pipes etc.?

No, just crack pipe unions to bleed pressure off and only worry if it doesn't stop.
Be careful storing part-full tank, do not assume the inlet/outlet valves are 100% sealing, they can seep.

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PostPosted: Mon Nov 04, 2013 10:26 am 
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fishmk1 wrote:
Is running an LPG system that switches back onto petrol when pushed hard a good thing or bad thing? Some people say it shows the system isn't up to the task of fuelling the engine, whereas others say that's what it is designed to do so full power is there when you need it.

It's designed to do that if the system can't cope with fuelling demands, not to regain performance. With a well set up, correctly specified gas system you shouldn't be able to tell what fuel you're on without looking at the switch. You'd probably be able to set up the system to part fuel with petrol under certain conditions, and some systems will secretly switch to petrol if the gas injector time gets to 100%.

There is some argument that running with some petrol at high loads helps with valve seat lubrication so that could be seen as a benefit. The extra fuel cost will depend at what point petrol starts to be used and how much time you spend driving past that point. It may not be significant.

Personally, as a DIYer myself, if the tank is reasonably suited and the kit is VERY cheap, I'd give it a go. Only IF you decide to stick with the existing system though which I'd think very carefully about. But if you start having to replace parts then the balance could swing the other way very quickly. Also, supplier support is useful for a first install although I'm sure this forum will be helpful ;)

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PostPosted: Mon Nov 04, 2013 3:47 pm 
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rossko wrote:
Cost it up ... secondhand tat + new pipes and hoses (you will do that, won't you?) + new reducer + new injectors >> buying a suitable new system in the first case.


The flexible pipes under the bonnet are 12mm feed and 6mm on the rail and I know I need bigger stuff so I was prepared for that, but I was going to reuse the underbody pipes from the tank to the engine bay. Is this a no-no? I was just going to inspect them for damage etc. and reuse them. I assumed the existing pipes from the tank etc. would cope if I went bigger on the injectors/reducer etc., is this not so?

rossko wrote:
LPG tank dimensions for model X is rarely the optimum fit for model Y; its another area that could be regretted later.


It's one of those spare wheel well ones. Diameter is spot on. It's would stick up about 2" when fitted in the Merc so yes, you're right. Not the end of the world but not ideal either.

rossko wrote:
It depends if you want to burn petrol or LPG. Presuming the whole object of the exercise is to burn LPG rather than petrol, fitting a pansy LPG system that can't actually achieve that seems to be a bit silly. It's no more difficult and hardly more expensive to fit adequate stuff to begin with. Correcting a poor choice later on will have a significant cost however.


rossko wrote:
Do not transplant a used system and expect OBD to sort it out. It will need manual setting up.


rossko wrote:
Who knows, it all depends on the spray pattern etc. Up to you to experiment. Most folk who have used those adaptors end up not using them again.


Hmm. I'm starting to see where you're coming from when you say it might be easier just getting the right kit to begin with!

rossko wrote:
No, just crack pipe unions to bleed pressure off and only worry if it doesn't stop.
Be careful storing part-full tank, do not assume the inlet/outlet valves are 100% sealing, they can seep.


I'll be giving this a go tonight so wish me luck! It needs removing from the Jag either way so he can scrap the car.

Thank you very much for your advice, much appreciated. :)


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PostPosted: Mon Nov 04, 2013 3:55 pm 
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No point in changing the underbonnet hoses as they need to be the correct size for the bits you are attaching them to. Completely pointless having an 8mm hose feeding an injector with a 6mm nipple. The most critical pipe is the one from the tank to the front end which could be either 6 or 8mm. If the existing install already has 8mm you may think it would be OK but you've obviously never tried to bend older copper pipe. It'll kink. If it already has flexible polypipe then you may be able to reuse it but I would have thought a pipe taken from a Jag wouldn't be long enough to fit to an E class Merc.

I've always considered switching to, or adding, petrol at high demand to be a bodge. Do you want a car that is converted to run on LPG or a car that is converted to run on LPG some of the time? A system specced for the car should never need to do it, if it does then it isn't up to the job. If petrol addition is needed to help prevent valve seat wear then you chose the wrong car to convert in the first place.

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PostPosted: Mon Nov 04, 2013 7:02 pm 
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The front to back pipe looks to be plastic so if it is long enough you could probably get away with reusing it.

Ideally you would want to upgrade the vapouriser and injectors but the Romano ECU only supports a limited range of injectors. You will have that messy heap of wiring to sort out.

As a first install then a new kit is the best way and you have not picked an easy car to do. That OBD fix is for use with mixer systems rather than mulit point.

If the kit is urber cheap then you had might aswell see what you can save.

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PostPosted: Tue Nov 05, 2013 5:11 pm 
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Thanks for the advice guys, I removed the existing kit from the Jag this morning. No problems so far, except I didn't realise until today that the LPG wiring harness is connected to the left bank of petrol injectors. Not sure yet if it's connected to just one or all four because I ran out of time but I may go back later and investigate :D


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PostPosted: Tue Nov 05, 2013 5:24 pm 
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It'll be connected to both banks. It intercepts the pulses from the petrol ECU and uses them to fire the gas injectors after adding a fiddle factor to the timings. The LPG controller doesn't replace the petrol ECU, it piggy backs onto it so the fuelling adjustments are still done by the petrol system.

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'93 Range Rover 4.2 LSE, Lovato LovEco, sold
'98 Ex-Police Range Rover 4.0, Singlepoint AEB Leo, my daily motor
'97 Range Rover 4.0SE, eGas multipoint, a project.....

Proud to be a member of the YCHJCYA2PDTHFH club.


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